root/net/mac80211/ibss.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * IBSS mode implementation
 * Copyright 2003-2008, Jouni Malinen <j@w1.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 * Copyright 2009, Johannes Berg <johannes@sipsolutions.net>
 * Copyright 2013-2014  Intel Mobile Communications GmbH
 * Copyright(c) 2016 Intel Deutschland GmbH
 * Copyright(c) 2018-2026 Intel Corporation
 */

#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_IBSS_JOIN_TIMEOUT (7 * HZ)

#define IEEE80211_IBSS_MERGE_INTERVAL (30 * HZ)
#define IEEE80211_IBSS_INACTIVITY_LIMIT (60 * HZ)
#define IEEE80211_IBSS_RSN_INACTIVITY_LIMIT (10 * HZ)

#define IEEE80211_IBSS_MAX_STA_ENTRIES 128

static struct beacon_data *
ieee80211_ibss_build_presp(struct ieee80211_sub_if_data *sdata,
                           const int beacon_int, const u32 basic_rates,
                           const u16 capability, u64 tsf,
                           struct cfg80211_chan_def *chandef,
                           bool *have_higher_than_11mbit,
                           struct cfg80211_csa_settings *csa_settings)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        int rates_n = 0, i, ri;
        struct ieee80211_mgmt *mgmt;
        u8 *pos;
        struct ieee80211_supported_band *sband;
        u32 rates = 0, rates_added = 0;
        struct beacon_data *presp;
        int frame_len;

        /* Build IBSS probe response */
        frame_len = 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 */ +
                    5 /* Channel Switch Announcement */ +
                    2 + (IEEE80211_MAX_SUPP_RATES - 8) +
                    2 + sizeof(struct ieee80211_ht_cap) +
                    2 + sizeof(struct ieee80211_ht_operation) +
                    2 + sizeof(struct ieee80211_vht_cap) +
                    2 + sizeof(struct ieee80211_vht_operation) +
                    ifibss->ie_len;
        presp = kzalloc(sizeof(*presp) + frame_len, GFP_KERNEL);
        if (!presp)
                return NULL;

        presp->head = (void *)(presp + 1);

        mgmt = (void *) presp->head;
        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 = (u8 *)mgmt + offsetof(struct ieee80211_mgmt, u.beacon.variable);

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

        sband = local->hw.wiphy->bands[chandef->chan->band];
        rates_n = 0;
        if (have_higher_than_11mbit)
                *have_higher_than_11mbit = false;

        for (i = 0; i < sband->n_bitrates; i++) {
                if (sband->bitrates[i].bitrate > 110 &&
                    have_higher_than_11mbit)
                        *have_higher_than_11mbit = true;

                rates |= BIT(i);
                rates_n++;
        }

        *pos++ = WLAN_EID_SUPP_RATES;
        *pos++ = min_t(int, 8, rates_n);
        for (ri = 0; ri < sband->n_bitrates; ri++) {
                int rate = DIV_ROUND_UP(sband->bitrates[ri].bitrate, 5);
                u8 basic = 0;
                if (!(rates & BIT(ri)))
                        continue;

                if (basic_rates & BIT(ri))
                        basic = 0x80;
                *pos++ = basic | (u8) rate;
                if (++rates_added == 8) {
                        ri++; /* continue at next rate for EXT_SUPP_RATES */
                        break;
                }
        }

        if (sband->band == NL80211_BAND_2GHZ) {
                *pos++ = WLAN_EID_DS_PARAMS;
                *pos++ = 1;
                *pos++ = ieee80211_frequency_to_channel(
                                chandef->chan->center_freq);
        }

        *pos++ = WLAN_EID_IBSS_PARAMS;
        *pos++ = 2;
        /* FIX: set ATIM window based on scan results */
        *pos++ = 0;
        *pos++ = 0;

        if (csa_settings) {
                *pos++ = WLAN_EID_CHANNEL_SWITCH;
                *pos++ = 3;
                *pos++ = csa_settings->block_tx ? 1 : 0;
                *pos++ = ieee80211_frequency_to_channel(
                                csa_settings->chandef.chan->center_freq);
                presp->cntdwn_counter_offsets[0] = (pos - presp->head);
                *pos++ = csa_settings->count;
                presp->cntdwn_current_counter = csa_settings->count;
        }

        /* put the remaining rates in WLAN_EID_EXT_SUPP_RATES */
        if (rates_n > 8) {
                *pos++ = WLAN_EID_EXT_SUPP_RATES;
                *pos++ = rates_n - 8;
                for (; ri < sband->n_bitrates; ri++) {
                        int rate = DIV_ROUND_UP(sband->bitrates[ri].bitrate, 5);
                        u8 basic = 0;
                        if (!(rates & BIT(ri)))
                                continue;

                        if (basic_rates & BIT(ri))
                                basic = 0x80;
                        *pos++ = basic | (u8) rate;
                }
        }

        if (ifibss->ie_len) {
                memcpy(pos, ifibss->ie, ifibss->ie_len);
                pos += ifibss->ie_len;
        }

        /* add HT capability and information IEs */
        if (chandef->width != NL80211_CHAN_WIDTH_20_NOHT &&
            sband->ht_cap.ht_supported) {
                struct ieee80211_sta_ht_cap ht_cap;

                memcpy(&ht_cap, &sband->ht_cap, sizeof(ht_cap));
                ieee80211_apply_htcap_overrides(sdata, &ht_cap);

                pos = ieee80211_ie_build_ht_cap(pos, &ht_cap, 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,
                                                 chandef, 0, false);

                /* add VHT capability and information IEs */
                if (chandef->width != NL80211_CHAN_WIDTH_20 &&
                    chandef->width != NL80211_CHAN_WIDTH_40 &&
                    sband->vht_cap.vht_supported) {
                        pos = ieee80211_ie_build_vht_cap(pos, &sband->vht_cap,
                                                         sband->vht_cap.cap);
                        pos = ieee80211_ie_build_vht_oper(pos, &sband->vht_cap,
                                                          chandef);
                }
        }

        if (local->hw.queues >= IEEE80211_NUM_ACS)
                pos = ieee80211_add_wmm_info_ie(pos, 0); /* U-APSD not in use */

        presp->head_len = pos - presp->head;
        if (WARN_ON(presp->head_len > frame_len))
                goto error;

        return presp;
error:
        kfree(presp);
        return NULL;
}

static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
                                      const u8 *bssid, const int beacon_int,
                                      struct cfg80211_chan_def *req_chandef,
                                      const u32 basic_rates,
                                      const u16 capability, u64 tsf,
                                      bool creator)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_mgmt *mgmt;
        struct cfg80211_bss *bss;
        u64 bss_change;
        struct ieee80211_chan_req chanreq = {};
        struct ieee80211_channel *chan;
        struct beacon_data *presp;
        struct cfg80211_inform_bss bss_meta = {};
        bool have_higher_than_11mbit;
        bool radar_required;
        int err;

        lockdep_assert_wiphy(local->hw.wiphy);

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

        if (!ether_addr_equal(ifibss->bssid, bssid))
                sta_info_flush(sdata, -1);

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

        presp = sdata_dereference(ifibss->presp, sdata);
        RCU_INIT_POINTER(ifibss->presp, NULL);
        if (presp)
                kfree_rcu(presp, rcu_head);

        /* make a copy of the chandef, it could be modified below. */
        chanreq.oper = *req_chandef;
        chan = chanreq.oper.chan;
        if (!cfg80211_reg_can_beacon(local->hw.wiphy, &chanreq.oper,
                                     NL80211_IFTYPE_ADHOC)) {
                if (chanreq.oper.width == NL80211_CHAN_WIDTH_20_NOHT ||
                    chanreq.oper.width == NL80211_CHAN_WIDTH_20) {
                        sdata_info(sdata,
                                   "Failed to join IBSS, beacons forbidden\n");
                        return;
                }
                chanreq.oper.width = NL80211_CHAN_WIDTH_20;
                chanreq.oper.center_freq1 = chan->center_freq;
                /* check again for downgraded chandef */
                if (!cfg80211_reg_can_beacon(local->hw.wiphy, &chanreq.oper,
                                             NL80211_IFTYPE_ADHOC)) {
                        sdata_info(sdata,
                                   "Failed to join IBSS, beacons forbidden\n");
                        return;
                }
        }

        err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
                                            &chanreq.oper, NL80211_IFTYPE_ADHOC);
        if (err < 0) {
                sdata_info(sdata,
                           "Failed to join IBSS, invalid chandef\n");
                return;
        }
        if (err > 0 && !ifibss->userspace_handles_dfs) {
                sdata_info(sdata,
                           "Failed to join IBSS, DFS channel without control program\n");
                return;
        }

        radar_required = err;

        if (ieee80211_link_use_channel(&sdata->deflink, &chanreq,
                                       ifibss->fixed_channel ?
                                        IEEE80211_CHANCTX_SHARED :
                                        IEEE80211_CHANCTX_EXCLUSIVE)) {
                sdata_info(sdata, "Failed to join IBSS, no channel context\n");
                return;
        }
        sdata->deflink.radar_required = radar_required;

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

        presp = ieee80211_ibss_build_presp(sdata, beacon_int, basic_rates,
                                           capability, tsf, &chanreq.oper,
                                           &have_higher_than_11mbit, NULL);
        if (!presp)
                return;

        rcu_assign_pointer(ifibss->presp, presp);
        mgmt = (void *)presp->head;

        sdata->vif.bss_conf.enable_beacon = true;
        sdata->vif.bss_conf.beacon_int = beacon_int;
        sdata->vif.bss_conf.basic_rates = basic_rates;
        sdata->vif.cfg.ssid_len = ifibss->ssid_len;
        memcpy(sdata->vif.cfg.ssid, ifibss->ssid, ifibss->ssid_len);
        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;
        bss_change |= BSS_CHANGED_SSID;

        /*
         * In 5 GHz/802.11a, we can always use short slot time.
         * (IEEE 802.11-2012 18.3.8.7)
         *
         * In 2.4GHz, we must always use long slots in IBSS for compatibility
         * reasons.
         * (IEEE 802.11-2012 19.4.5)
         *
         * HT follows these specifications (IEEE 802.11-2012 20.3.18)
         */
        sdata->vif.bss_conf.use_short_slot = chan->band == NL80211_BAND_5GHZ;
        bss_change |= BSS_CHANGED_ERP_SLOT;

        /* cf. IEEE 802.11 9.2.12 */
        sdata->deflink.operating_11g_mode =
                chan->band == NL80211_BAND_2GHZ && have_higher_than_11mbit;

        ieee80211_set_wmm_default(&sdata->deflink, true, false);

        sdata->vif.cfg.ibss_joined = true;
        sdata->vif.cfg.ibss_creator = creator;

        err = drv_join_ibss(local, sdata);
        if (err) {
                sdata->vif.cfg.ibss_joined = false;
                sdata->vif.cfg.ibss_creator = false;
                sdata->vif.bss_conf.enable_beacon = false;
                sdata->vif.cfg.ssid_len = 0;
                RCU_INIT_POINTER(ifibss->presp, NULL);
                kfree_rcu(presp, rcu_head);
                ieee80211_link_release_channel(&sdata->deflink);
                sdata_info(sdata, "Failed to join IBSS, driver failure: %d\n",
                           err);
                return;
        }

        ieee80211_bss_info_change_notify(sdata, bss_change);

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

        bss_meta.chan = chan;
        bss = cfg80211_inform_bss_frame_data(local->hw.wiphy, &bss_meta, mgmt,
                                             presp->head_len, GFP_KERNEL);

        cfg80211_put_bss(local->hw.wiphy, bss);
        netif_carrier_on(sdata->dev);
        cfg80211_ibss_joined(sdata->dev, ifibss->bssid, chan, 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;
        struct cfg80211_chan_def chandef;
        u32 basic_rates;
        int i, j;
        u16 beacon_int = cbss->beacon_interval;
        const struct cfg80211_bss_ies *ies;
        enum nl80211_channel_type chan_type;
        u64 tsf;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        if (beacon_int < 10)
                beacon_int = 10;

        switch (sdata->u.ibss.chandef.width) {
        case NL80211_CHAN_WIDTH_20_NOHT:
        case NL80211_CHAN_WIDTH_20:
        case NL80211_CHAN_WIDTH_40:
                chan_type = cfg80211_get_chandef_type(&sdata->u.ibss.chandef);
                cfg80211_chandef_create(&chandef, cbss->channel, chan_type);
                break;
        case NL80211_CHAN_WIDTH_80:
        case NL80211_CHAN_WIDTH_80P80:
        case NL80211_CHAN_WIDTH_160:
                chandef = sdata->u.ibss.chandef;
                chandef.chan = cbss->channel;
                break;
        default:
                /* fall back to 20 MHz for unsupported modes */
                cfg80211_chandef_create(&chandef, cbss->channel,
                                        NL80211_CHAN_NO_HT);
                break;
        }

        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;
                bool is_basic = !!(bss->supp_rates[i] & 0x80);

                for (j = 0; j < sband->n_bitrates; j++) {
                        int brate;

                        brate = DIV_ROUND_UP(sband->bitrates[j].bitrate, 5);
                        if (brate == rate) {
                                if (is_basic)
                                        basic_rates |= BIT(j);
                                break;
                        }
                }
        }

        rcu_read_lock();
        ies = rcu_dereference(cbss->ies);
        tsf = ies->tsf;
        rcu_read_unlock();

        __ieee80211_sta_join_ibss(sdata, cbss->bssid,
                                  beacon_int,
                                  &chandef,
                                  basic_rates,
                                  cbss->capability,
                                  tsf, false);
}

int ieee80211_ibss_csa_beacon(struct ieee80211_sub_if_data *sdata,
                              struct cfg80211_csa_settings *csa_settings,
                              u64 *changed)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct beacon_data *presp, *old_presp;
        struct cfg80211_bss *cbss;
        const struct cfg80211_bss_ies *ies;
        u16 capability = WLAN_CAPABILITY_IBSS;
        u64 tsf;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

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

        cbss = cfg80211_get_bss(sdata->local->hw.wiphy, ifibss->chandef.chan,
                                ifibss->bssid, ifibss->ssid,
                                ifibss->ssid_len, IEEE80211_BSS_TYPE_IBSS,
                                IEEE80211_PRIVACY(ifibss->privacy));

        if (unlikely(!cbss))
                return -EINVAL;

        rcu_read_lock();
        ies = rcu_dereference(cbss->ies);
        tsf = ies->tsf;
        rcu_read_unlock();
        cfg80211_put_bss(sdata->local->hw.wiphy, cbss);

        old_presp = sdata_dereference(ifibss->presp, sdata);

        presp = ieee80211_ibss_build_presp(sdata,
                                           sdata->vif.bss_conf.beacon_int,
                                           sdata->vif.bss_conf.basic_rates,
                                           capability, tsf, &ifibss->chandef,
                                           NULL, csa_settings);
        if (!presp)
                return -ENOMEM;

        rcu_assign_pointer(ifibss->presp, presp);
        if (old_presp)
                kfree_rcu(old_presp, rcu_head);

        *changed |= BSS_CHANGED_BEACON;
        return 0;
}

int ieee80211_ibss_finish_csa(struct ieee80211_sub_if_data *sdata, u64 *changed)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct cfg80211_bss *cbss;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        /* When not connected/joined, sending CSA doesn't make sense. */
        if (ifibss->state != IEEE80211_IBSS_MLME_JOINED)
                return -ENOLINK;

        /* update cfg80211 bss information with the new channel */
        if (!is_zero_ether_addr(ifibss->bssid)) {
                cbss = cfg80211_get_bss(sdata->local->hw.wiphy,
                                        ifibss->chandef.chan,
                                        ifibss->bssid, ifibss->ssid,
                                        ifibss->ssid_len,
                                        IEEE80211_BSS_TYPE_IBSS,
                                        IEEE80211_PRIVACY(ifibss->privacy));
                /* XXX: should not really modify cfg80211 data */
                if (cbss) {
                        cbss->channel = sdata->deflink.csa.chanreq.oper.chan;
                        cfg80211_put_bss(sdata->local->hw.wiphy, cbss);
                }
        }

        ifibss->chandef = sdata->deflink.csa.chanreq.oper;

        /* generate the beacon */
        return ieee80211_ibss_csa_beacon(sdata, NULL, changed);
}

void ieee80211_ibss_stop(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        wiphy_work_cancel(sdata->local->hw.wiphy,
                          &ifibss->csa_connection_drop_work);
}

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

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

        ieee80211_sta_init_nss_bw_capa(&sta->deflink,
                                       &sdata->deflink.conf->chanreq.oper);

        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->deflink);

        /* If it fails, maybe we raced another insertion? */
        if (sta_info_insert_rcu(sta))
                return sta_info_get(sdata, addr);
        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)
        __acquires(RCU)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_supported_band *sband;
        int 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;
        }

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.bss_conf.chanctx_conf);
        if (WARN_ON_ONCE(!chanctx_conf))
                return NULL;
        band = chanctx_conf->def.chan->band;
        rcu_read_unlock();

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

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

        return ieee80211_ibss_finish_sta(sta);
}

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_wiphy(sdata->local->hw.wiphy);

        rcu_read_lock();

        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                unsigned long last_active = ieee80211_sta_last_active(sta, -1);

                if (sta->sdata == sdata &&
                    time_is_after_jiffies(last_active +
                                          IEEE80211_IBSS_MERGE_INTERVAL)) {
                        active++;
                        break;
                }
        }

        rcu_read_unlock();

        return active;
}

static void ieee80211_ibss_disconnect(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 beacon_data *presp;
        struct sta_info *sta;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (!is_zero_ether_addr(ifibss->bssid)) {
                cbss = cfg80211_get_bss(local->hw.wiphy, ifibss->chandef.chan,
                                        ifibss->bssid, ifibss->ssid,
                                        ifibss->ssid_len,
                                        IEEE80211_BSS_TYPE_IBSS,
                                        IEEE80211_PRIVACY(ifibss->privacy));

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

        ifibss->state = IEEE80211_IBSS_MLME_SEARCH;

        netif_carrier_off(sdata->dev);
        if (!sta_info_flush(sdata, -1))
                synchronize_net();

        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);

        sdata->vif.cfg.ibss_joined = false;
        sdata->vif.cfg.ibss_creator = false;
        sdata->vif.bss_conf.enable_beacon = false;
        sdata->vif.cfg.ssid_len = 0;

        /* remove beacon */
        presp = sdata_dereference(ifibss->presp, sdata);
        RCU_INIT_POINTER(sdata->u.ibss.presp, NULL);
        if (presp)
                kfree_rcu(presp, rcu_head);

        clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED |
                                                BSS_CHANGED_IBSS);
        drv_leave_ibss(local, sdata);
        ieee80211_link_release_channel(&sdata->deflink);
}

static void ieee80211_csa_connection_drop_work(struct wiphy *wiphy,
                                               struct wiphy_work *work)
{
        struct ieee80211_sub_if_data *sdata =
                container_of(work, struct ieee80211_sub_if_data,
                             u.ibss.csa_connection_drop_work);

        ieee80211_ibss_disconnect(sdata);
        skb_queue_purge(&sdata->skb_queue);

        /* trigger a scan to find another IBSS network to join */
        wiphy_work_queue(sdata->local->hw.wiphy, &sdata->work);
}

static void ieee80211_ibss_csa_mark_radar(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        int err;

        /* if the current channel is a DFS channel, mark the channel as
         * unavailable.
         */
        err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
                                            &ifibss->chandef,
                                            NL80211_IFTYPE_ADHOC);
        if (err > 0)
                cfg80211_radar_event(sdata->local->hw.wiphy, &ifibss->chandef,
                                     GFP_ATOMIC);
}

static bool
ieee80211_ibss_process_chanswitch(struct ieee80211_sub_if_data *sdata,
                                  struct ieee802_11_elems *elems,
                                  bool beacon)
{
        struct cfg80211_csa_settings params;
        struct ieee80211_csa_ie csa_ie;
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        enum nl80211_channel_type ch_type;
        int err;
        struct ieee80211_conn_settings conn = {
                .mode = IEEE80211_CONN_MODE_HT,
                .bw_limit = IEEE80211_CONN_BW_LIMIT_40,
        };
        u32 vht_cap_info = 0;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        switch (ifibss->chandef.width) {
        case NL80211_CHAN_WIDTH_20_NOHT:
                conn.mode = IEEE80211_CONN_MODE_LEGACY;
                fallthrough;
        case NL80211_CHAN_WIDTH_20:
                conn.bw_limit = IEEE80211_CONN_BW_LIMIT_20;
                break;
        default:
                break;
        }

        if (elems->vht_cap_elem)
                vht_cap_info = le32_to_cpu(elems->vht_cap_elem->vht_cap_info);

        memset(&params, 0, sizeof(params));
        err = ieee80211_parse_ch_switch_ie(sdata, elems,
                                           ifibss->chandef.chan->band,
                                           vht_cap_info, &conn,
                                           ifibss->bssid, false,
                                           &csa_ie);
        /* can't switch to destination channel, fail */
        if (err < 0)
                goto disconnect;

        /* did not contain a CSA */
        if (err)
                return false;

        /* channel switch is not supported, disconnect */
        if (!(sdata->local->hw.wiphy->flags & WIPHY_FLAG_HAS_CHANNEL_SWITCH))
                goto disconnect;

        params.count = csa_ie.count;
        params.chandef = csa_ie.chanreq.oper;

        switch (ifibss->chandef.width) {
        case NL80211_CHAN_WIDTH_20_NOHT:
        case NL80211_CHAN_WIDTH_20:
        case NL80211_CHAN_WIDTH_40:
                /* keep our current HT mode (HT20/HT40+/HT40-), even if
                 * another mode  has been announced. The mode is not adopted
                 * within the beacon while doing CSA and we should therefore
                 * keep the mode which we announce.
                 */
                ch_type = cfg80211_get_chandef_type(&ifibss->chandef);
                cfg80211_chandef_create(&params.chandef, params.chandef.chan,
                                        ch_type);
                break;
        default:
                /* should not happen, conn_flags should prevent VHT modes. */
                WARN_ON(1);
                goto disconnect;
        }

        if (!cfg80211_reg_can_beacon(sdata->local->hw.wiphy, &params.chandef,
                                     NL80211_IFTYPE_ADHOC)) {
                sdata_info(sdata,
                           "IBSS %pM switches to unsupported channel (%d MHz, width:%d, CF1/2: %d/%d MHz), disconnecting\n",
                           ifibss->bssid,
                           params.chandef.chan->center_freq,
                           params.chandef.width,
                           params.chandef.center_freq1,
                           params.chandef.center_freq2);
                goto disconnect;
        }

        err = cfg80211_chandef_dfs_required(sdata->local->hw.wiphy,
                                            &params.chandef,
                                            NL80211_IFTYPE_ADHOC);
        if (err < 0)
                goto disconnect;
        if (err > 0 && !ifibss->userspace_handles_dfs) {
                /* IBSS-DFS only allowed with a control program */
                goto disconnect;
        }

        params.radar_required = err;

        if (cfg80211_chandef_identical(&params.chandef,
                                       &sdata->vif.bss_conf.chanreq.oper)) {
                ibss_dbg(sdata,
                         "received csa with an identical chandef, ignoring\n");
                return true;
        }

        /* all checks done, now perform the channel switch. */
        ibss_dbg(sdata,
                 "received channel switch announcement to go to channel %d MHz\n",
                 params.chandef.chan->center_freq);

        params.block_tx = !!csa_ie.mode;

        if (ieee80211_channel_switch(sdata->local->hw.wiphy, sdata->dev,
                                     &params))
                goto disconnect;

        ieee80211_ibss_csa_mark_radar(sdata);

        return true;
disconnect:
        ibss_dbg(sdata, "Can't handle channel switch, disconnect\n");
        wiphy_work_queue(sdata->local->hw.wiphy,
                         &ifibss->csa_connection_drop_work);

        ieee80211_ibss_csa_mark_radar(sdata);

        return true;
}

static void
ieee80211_rx_mgmt_spectrum_mgmt(struct ieee80211_sub_if_data *sdata,
                                struct ieee80211_mgmt *mgmt, size_t len,
                                struct ieee80211_rx_status *rx_status,
                                struct ieee802_11_elems *elems)
{
        if (len < IEEE80211_MIN_ACTION_SIZE(chan_switch))
                return;

        /* CSA is the only action we handle for now */
        if (mgmt->u.action.action_code != WLAN_ACTION_SPCT_CHL_SWITCH)
                return;

        if (!sdata->vif.bss_conf.csa_active)
                ieee80211_ibss_process_chanswitch(sdata, elems, false);
}

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\n", mgmt->sa, mgmt->da);
        ibss_dbg(sdata, "\tBSSID=%pM (reason: %d)\n", 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;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        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);

        ibss_dbg(sdata, "RX Auth SA=%pM DA=%pM\n", mgmt->sa, mgmt->da);
        ibss_dbg(sdata, "\tBSSID=%pM (auth_transaction=%d)\n",
                 mgmt->bssid, auth_transaction);

        if (auth_alg != WLAN_AUTH_OPEN || auth_transaction != 1)
                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, 0, NULL, 0,
                            mgmt->sa, sdata->u.ibss.bssid, NULL, 0, 0, 0);
}

static void ieee80211_update_sta_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,
                                      struct ieee80211_channel *channel)
{
        struct sta_info *sta;
        enum nl80211_band band = rx_status->band;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_supported_band *sband;
        bool rates_updated = false;
        u32 supp_rates = 0;

        if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
                return;

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

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

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

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

                        prev_rates = sta->sta.deflink.supp_rates[band];

                        sta->sta.deflink.supp_rates[band] = supp_rates |
                                ieee80211_mandatory_rates(sband);
                        if (sta->sta.deflink.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.deflink.supp_rates[band]);
                                rates_updated = true;
                        }
                } else {
                        rcu_read_unlock();
                        sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid,
                                                     mgmt->sa, supp_rates);
                }
        }

        if (sta && !sta->sta.wme &&
            (elems->wmm_info || elems->s1g_capab) &&
            local->hw.queues >= IEEE80211_NUM_ACS) {
                sta->sta.wme = true;
                ieee80211_check_fast_xmit(sta);
        }

        if (sta && elems->ht_operation && elems->ht_cap_elem &&
            sdata->u.ibss.chandef.width != NL80211_CHAN_WIDTH_20_NOHT) {
                /* we both use HT */
                struct ieee80211_ht_cap htcap_ie;
                struct cfg80211_chan_def chandef;
                enum ieee80211_sta_rx_bandwidth bw = sta->sta.deflink.bandwidth;

                cfg80211_chandef_create(&chandef, channel, NL80211_CHAN_NO_HT);
                ieee80211_chandef_ht_oper(elems->ht_operation, &chandef);

                memcpy(&htcap_ie, elems->ht_cap_elem, sizeof(htcap_ie));
                rates_updated |= ieee80211_ht_cap_ie_to_sta_ht_cap(sdata,
                                                                   &sband->ht_cap,
                                                                   &htcap_ie,
                                                                   &sta->deflink);

                if (elems->vht_operation && elems->vht_cap_elem &&
                    sdata->u.ibss.chandef.width != NL80211_CHAN_WIDTH_20 &&
                    sdata->u.ibss.chandef.width != NL80211_CHAN_WIDTH_40) {
                        /* we both use VHT */
                        struct ieee80211_vht_cap cap_ie;
                        struct ieee80211_sta_vht_cap cap = sta->sta.deflink.vht_cap;
                        u32 vht_cap_info =
                                le32_to_cpu(elems->vht_cap_elem->vht_cap_info);

                        ieee80211_chandef_vht_oper(&local->hw, vht_cap_info,
                                                   elems->vht_operation,
                                                   elems->ht_operation,
                                                   &chandef);
                        memcpy(&cap_ie, elems->vht_cap_elem, sizeof(cap_ie));
                        ieee80211_vht_cap_ie_to_sta_vht_cap(sdata, sband,
                                                            &sband->vht_cap,
                                                            &cap_ie, NULL,
                                                            &sta->deflink);
                        if (memcmp(&cap, &sta->sta.deflink.vht_cap, sizeof(cap)))
                                rates_updated |= true;
                }

                if (bw != sta->sta.deflink.bandwidth)
                        rates_updated |= true;

                if (!cfg80211_chandef_compatible(&sdata->u.ibss.chandef,
                                                 &chandef))
                        WARN_ON_ONCE(1);
        }

        if (sta && rates_updated) {
                u32 changed = IEEE80211_RC_SUPP_RATES_CHANGED;
                u8 rx_nss = sta->sta.deflink.rx_nss;

                ieee80211_sta_init_nss_bw_capa(&sta->deflink,
                                               &sdata->deflink.conf->chanreq.oper);
                rate_control_rate_init(&sta->deflink);
                if (sta->sta.deflink.rx_nss != rx_nss)
                        changed |= IEEE80211_RC_NSS_CHANGED;

                drv_link_sta_rc_update(local, sdata, &sta->sta.deflink,
                                       changed);
        }

        rcu_read_unlock();
}

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)
{
        struct ieee80211_local *local = sdata->local;
        struct cfg80211_bss *cbss;
        struct ieee80211_bss *bss;
        struct ieee80211_channel *channel;
        u64 beacon_timestamp, rx_timestamp;
        u32 supp_rates = 0;
        enum nl80211_band band = rx_status->band;

        channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
        if (!channel)
                return;

        ieee80211_update_sta_info(sdata, mgmt, len, rx_status, elems, channel);

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

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

        /* same for beacon and probe response */
        beacon_timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);

        /* check if we need to merge IBSS */

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

        /* different channel */
        if (sdata->u.ibss.fixed_channel &&
            sdata->u.ibss.chandef.chan != cbss->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;

        /* process channel switch */
        if (sdata->vif.bss_conf.csa_active ||
            ieee80211_ibss_process_chanswitch(sdata, elems, true))
                goto put_bss;

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

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

        if (ieee80211_have_rx_timestamp(rx_status)) {
                /* time when timestamp field was received */
                rx_timestamp =
                        ieee80211_calculate_rx_timestamp(&local->hw, rx_status,
                                                         len + FCS_LEN, 24);
        } 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\n",
                 mgmt->sa, mgmt->bssid,
                 (unsigned long long)rx_timestamp);
        ibss_dbg(sdata, "\tBCN=0x%llx diff=%lld @%lu\n",
                 (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(sdata, elems, band, NULL);
                ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
                                       supp_rates);
                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;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_supported_band *sband;
        int 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;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.bss_conf.chanctx_conf);
        if (WARN_ON_ONCE(!chanctx_conf)) {
                rcu_read_unlock();
                return;
        }
        band = chanctx_conf->def.chan->band;
        rcu_read_unlock();

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

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

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

static void ieee80211_ibss_sta_expire(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta, *tmp;
        unsigned long exp_time = IEEE80211_IBSS_INACTIVITY_LIMIT;
        unsigned long exp_rsn = IEEE80211_IBSS_RSN_INACTIVITY_LIMIT;

        lockdep_assert_wiphy(local->hw.wiphy);

        list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
                unsigned long last_active = ieee80211_sta_last_active(sta, -1);

                if (sdata != sta->sdata)
                        continue;

                if (time_is_before_jiffies(last_active + exp_time) ||
                    (time_is_before_jiffies(last_active + exp_rsn) &&
                     sta->sta_state != IEEE80211_STA_AUTHORIZED)) {
                        u8 frame_buf[IEEE80211_DEAUTH_FRAME_LEN];

                        sta_dbg(sta->sdata, "expiring inactive %sSTA %pM\n",
                                sta->sta_state != IEEE80211_STA_AUTHORIZED ?
                                "not authorized " : "", sta->sta.addr);

                        ieee80211_send_deauth_disassoc(sdata, sta->sta.addr,
                                                       ifibss->bssid,
                                                       IEEE80211_STYPE_DEAUTH,
                                                       WLAN_REASON_DEAUTH_LEAVING,
                                                       true, frame_buf);
                        WARN_ON(__sta_info_destroy(sta));
                }
        }
}

/*
 * 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_wiphy(sdata->local->hw.wiphy);

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

        ieee80211_ibss_sta_expire(sdata);

        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_ibss_scan(sdata, ifibss->ssid, ifibss->ssid_len,
                                    NULL, 0);
}

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_wiphy(sdata->local->hw.wiphy);

        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;

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

static unsigned int ibss_setup_channels(struct wiphy *wiphy,
                                        struct ieee80211_channel **channels,
                                        unsigned int channels_max,
                                        u32 center_freq, u32 width)
{
        struct ieee80211_channel *chan = NULL;
        unsigned int n_chan = 0;
        u32 start_freq, end_freq, freq;

        if (width <= 20) {
                start_freq = center_freq;
                end_freq = center_freq;
        } else {
                start_freq = center_freq - width / 2 + 10;
                end_freq = center_freq + width / 2 - 10;
        }

        for (freq = start_freq; freq <= end_freq; freq += 20) {
                chan = ieee80211_get_channel(wiphy, freq);
                if (!chan)
                        continue;
                if (n_chan >= channels_max)
                        return n_chan;

                channels[n_chan] = chan;
                n_chan++;
        }

        return n_chan;
}

static unsigned int
ieee80211_ibss_setup_scan_channels(struct wiphy *wiphy,
                                   const struct cfg80211_chan_def *chandef,
                                   struct ieee80211_channel **channels,
                                   unsigned int channels_max)
{
        unsigned int n_chan = 0;
        u32 width, cf1, cf2 = 0;

        switch (chandef->width) {
        case NL80211_CHAN_WIDTH_40:
                width = 40;
                break;
        case NL80211_CHAN_WIDTH_80P80:
                cf2 = chandef->center_freq2;
                fallthrough;
        case NL80211_CHAN_WIDTH_80:
                width = 80;
                break;
        case NL80211_CHAN_WIDTH_160:
                width = 160;
                break;
        default:
                width = 20;
                break;
        }

        cf1 = chandef->center_freq1;

        n_chan = ibss_setup_channels(wiphy, channels, channels_max, cf1, width);

        if (cf2)
                n_chan += ibss_setup_channels(wiphy, &channels[n_chan],
                                              channels_max - n_chan, cf2,
                                              width);

        return n_chan;
}

/*
 * 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;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

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

        if (active_ibss)
                return;

        if (ifibss->fixed_bssid)
                bssid = ifibss->bssid;
        if (ifibss->fixed_channel)
                chan = ifibss->chandef.chan;
        if (!is_zero_ether_addr(ifibss->bssid))
                bssid = ifibss->bssid;
        cbss = cfg80211_get_bss(local->hw.wiphy, chan, bssid,
                                ifibss->ssid, ifibss->ssid_len,
                                IEEE80211_BSS_TYPE_IBSS,
                                IEEE80211_PRIVACY(ifibss->privacy));

        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;
        }

        /* if a fixed bssid and a fixed freq have been provided create the IBSS
         * directly and do not waste time scanning
         */
        if (ifibss->fixed_bssid && ifibss->fixed_channel) {
                sdata_info(sdata, "Created IBSS using preconfigured BSSID %pM\n",
                           bssid);
                ieee80211_sta_create_ibss(sdata);
                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)) {
                struct ieee80211_channel *channels[8];
                unsigned int num;

                sdata_info(sdata, "Trigger new scan to find an IBSS to join\n");

                if (ifibss->fixed_channel) {
                        num = ieee80211_ibss_setup_scan_channels(local->hw.wiphy,
                                                                 &ifibss->chandef,
                                                                 channels,
                                                                 ARRAY_SIZE(channels));
                        ieee80211_request_ibss_scan(sdata, ifibss->ssid,
                                                    ifibss->ssid_len, channels,
                                                    num);
                } else {
                        ieee80211_request_ibss_scan(sdata, ifibss->ssid,
                                                    ifibss->ssid_len, NULL, 0);
                }
        } else {
                int interval = IEEE80211_SCAN_INTERVAL;

                if (time_after(jiffies, ifibss->ibss_join_req +
                               IEEE80211_IBSS_JOIN_TIMEOUT))
                        ieee80211_sta_create_ibss(sdata);

                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 beacon_data *presp;
        u8 *pos, *end;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        presp = sdata_dereference(ifibss->presp, sdata);

        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\n", mgmt->sa, mgmt->da);
        ibss_dbg(sdata, "\tBSSID=%pM (tx_last_beacon=%d)\n",
                 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 = dev_alloc_skb(local->tx_headroom + presp->head_len);
        if (!skb)
                return;

        skb_reserve(skb, local->tx_headroom);
        skb_put_data(skb, presp->head, presp->head_len);

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

        /* avoid excessive retries for probe request to wildcard SSIDs */
        if (pos[1] == 0)
                IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_NO_ACK;

        ieee80211_tx_skb(sdata, skb);
}

static
void ieee80211_rx_mgmt_probe_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;
        u16 type;

        BUILD_BUG_ON(offsetof(typeof(mgmt->u.probe_resp), variable) !=
                     offsetof(typeof(mgmt->u.beacon), variable));

        /*
         * either beacon or probe_resp but the variable field is at the
         * same offset
         */
        baselen = (u8 *) mgmt->u.probe_resp.variable - (u8 *) mgmt;
        if (baselen > len)
                return;

        type = le16_to_cpu(mgmt->frame_control) & IEEE80211_FCTL_TYPE;
        elems = ieee802_11_parse_elems(mgmt->u.probe_resp.variable,
                                       len - baselen, type, NULL);

        if (elems) {
                ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, elems);
                kfree(elems);
        }
}

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;
        struct ieee802_11_elems *elems;
        int ies_len;

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

        if (!sdata->u.ibss.ssid_len)
                return; /* 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:
        case IEEE80211_STYPE_BEACON:
                ieee80211_rx_mgmt_probe_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;
        case IEEE80211_STYPE_ACTION:
                switch (mgmt->u.action.category) {
                case WLAN_CATEGORY_SPECTRUM_MGMT:
                        ies_len = skb->len -
                                  offsetof(struct ieee80211_mgmt,
                                           u.action.chan_switch.variable);

                        if (ies_len < 0)
                                break;

                        elems = ieee802_11_parse_elems(mgmt->u.action.chan_switch.variable,
                                                       ies_len,
                                                       IEEE80211_FTYPE_MGMT |
                                                       IEEE80211_STYPE_ACTION,
                                                       NULL);

                        if (elems && !elems->parse_error)
                                ieee80211_rx_mgmt_spectrum_mgmt(sdata, mgmt,
                                                                skb->len,
                                                                rx_status,
                                                                elems);
                        kfree(elems);
                        break;
                }
        }
}

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

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

        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);
                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;
        }
}

static void ieee80211_ibss_timer(struct timer_list *t)
{
        struct ieee80211_sub_if_data *sdata =
                timer_container_of(sdata, t, u.ibss.timer);

        wiphy_work_queue(sdata->local->hw.wiphy, &sdata->work);
}

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

        timer_setup(&ifibss->timer, ieee80211_ibss_timer, 0);
        INIT_LIST_HEAD(&ifibss->incomplete_stations);
        spin_lock_init(&ifibss->incomplete_lock);
        wiphy_work_init(&ifibss->csa_connection_drop_work,
                        ieee80211_csa_connection_drop_work);
}

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

        lockdep_assert_wiphy(local->hw.wiphy);

        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;
        }
}

int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
                        struct cfg80211_ibss_params *params)
{
        u64 changed = 0;
        enum ieee80211_chanctx_mode chanmode;
        struct ieee80211_local *local = sdata->local;
        int radar_detect_width = 0;
        int ret;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (params->chandef.chan->freq_offset) {
                /* this may work, but is untested */
                return -EOPNOTSUPP;
        }

        ret = cfg80211_chandef_dfs_required(local->hw.wiphy,
                                            &params->chandef,
                                            sdata->wdev.iftype);
        if (ret < 0)
                return ret;

        if (ret > 0) {
                if (!params->userspace_handles_dfs)
                        return -EINVAL;
                radar_detect_width = BIT(params->chandef.width);
        }

        chanmode = (params->channel_fixed && !ret) ?
                IEEE80211_CHANCTX_SHARED : IEEE80211_CHANCTX_EXCLUSIVE;

        ret = ieee80211_check_combinations(sdata, &params->chandef, chanmode,
                                           radar_detect_width, -1);
        if (ret < 0)
                return ret;

        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.userspace_handles_dfs = params->userspace_handles_dfs;
        sdata->u.ibss.basic_rates = params->basic_rates;
        sdata->u.ibss.last_scan_completed = jiffies;

        /* fix basic_rates if channel does not support these 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.chandef = params->chandef;
        sdata->u.ibss.fixed_channel = params->channel_fixed;

        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.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;

        memcpy(&sdata->u.ibss.ht_capa, &params->ht_capa,
               sizeof(sdata->u.ibss.ht_capa));
        memcpy(&sdata->u.ibss.ht_capa_mask, &params->ht_capa_mask,
               sizeof(sdata->u.ibss.ht_capa_mask));

        /*
         * 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 | BSS_CHANGED_MCAST_RATE;
        ieee80211_link_info_change_notify(sdata, &sdata->deflink, changed);

        sdata->deflink.smps_mode = IEEE80211_SMPS_OFF;
        sdata->deflink.needed_rx_chains = local->rx_chains;
        sdata->control_port_over_nl80211 = params->control_port_over_nl80211;

        wiphy_work_queue(local->hw.wiphy, &sdata->work);

        return 0;
}

int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        ifibss->ssid_len = 0;
        ieee80211_ibss_disconnect(sdata);
        eth_zero_addr(ifibss->bssid);

        /* remove beacon */
        kfree(sdata->u.ibss.ie);
        sdata->u.ibss.ie = NULL;
        sdata->u.ibss.ie_len = 0;

        /* on the next join, re-program HT parameters */
        memset(&ifibss->ht_capa, 0, sizeof(ifibss->ht_capa));
        memset(&ifibss->ht_capa_mask, 0, sizeof(ifibss->ht_capa_mask));

        skb_queue_purge(&sdata->skb_queue);

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

        return 0;
}