work.c

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/*
 * mac80211 work 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>
 *
 * 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/if_ether.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>
#include <linux/slab.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>

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

#define IEEE80211_AUTH_TIMEOUT (HZ / 5)
#define IEEE80211_AUTH_MAX_TRIES 3
#define IEEE80211_ASSOC_TIMEOUT (HZ / 5)
#define IEEE80211_ASSOC_MAX_TRIES 3

enum work_action {
        WORK_ACT_MISMATCH,
        WORK_ACT_NONE,
        WORK_ACT_TIMEOUT,
        WORK_ACT_DONE,
};


/* utils */
static inline void ASSERT_WORK_MTX(struct ieee80211_local *local)
{
        lockdep_assert_held(&local->mtx);
}

/*
 * We can have multiple work items (and connection probing)
 * scheduling this timer, but we need to take care to only
 * reschedule it when it should fire _earlier_ than it was
 * asked for before, or if it's not pending right now. This
 * function ensures that. Note that it then is required to
 * run this function for all timeouts after the first one
 * has happened -- the work that runs from this timer will
 * do that.
 */
static void run_again(struct ieee80211_local *local,
                      unsigned long timeout)
{
        ASSERT_WORK_MTX(local);

        if (!timer_pending(&local->work_timer) ||
            time_before(timeout, local->work_timer.expires))
                mod_timer(&local->work_timer, timeout);
}

void free_work(struct ieee80211_work *wk)
{
        kfree_rcu(wk, rcu_head);
}

static int ieee80211_compatible_rates(const u8 *supp_rates, int supp_rates_len,
                                      struct ieee80211_supported_band *sband,
                                      u32 *rates)
{
        int i, j, count;
        *rates = 0;
        count = 0;
        for (i = 0; i < supp_rates_len; i++) {
                int rate = (supp_rates[i] & 0x7F) * 5;

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

        return count;
}

/* frame sending functions */

static void ieee80211_add_ht_ie(struct sk_buff *skb, const u8 *ht_info_ie,
                                struct ieee80211_supported_band *sband,
                                struct ieee80211_channel *channel,
                                enum ieee80211_smps_mode smps)
{
        struct ieee80211_ht_info *ht_info;
        u8 *pos;
        u32 flags = channel->flags;
        u16 cap = sband->ht_cap.cap;
        __le16 tmp;

        if (!sband->ht_cap.ht_supported)
                return;

        if (!ht_info_ie)
                return;

        if (ht_info_ie[1] < sizeof(struct ieee80211_ht_info))
                return;

        ht_info = (struct ieee80211_ht_info *)(ht_info_ie + 2);

        /* determine capability flags */

        switch (ht_info->ht_param & IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
        case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
                if (flags & IEEE80211_CHAN_NO_HT40PLUS) {
                        cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
                        cap &= ~IEEE80211_HT_CAP_SGI_40;
                }
                break;
        case IEEE80211_HT_PARAM_CHA_SEC_BELOW:
                if (flags & IEEE80211_CHAN_NO_HT40MINUS) {
                        cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
                        cap &= ~IEEE80211_HT_CAP_SGI_40;
                }
                break;
        }

        /* set SM PS mode properly */
        cap &= ~IEEE80211_HT_CAP_SM_PS;
        switch (smps) {
        case IEEE80211_SMPS_AUTOMATIC:
        case IEEE80211_SMPS_NUM_MODES:
                WARN_ON(1);
        case IEEE80211_SMPS_OFF:
                cap |= WLAN_HT_CAP_SM_PS_DISABLED <<
                        IEEE80211_HT_CAP_SM_PS_SHIFT;
                break;
        case IEEE80211_SMPS_STATIC:
                cap |= WLAN_HT_CAP_SM_PS_STATIC <<
                        IEEE80211_HT_CAP_SM_PS_SHIFT;
                break;
        case IEEE80211_SMPS_DYNAMIC:
                cap |= WLAN_HT_CAP_SM_PS_DYNAMIC <<
                        IEEE80211_HT_CAP_SM_PS_SHIFT;
                break;
        }

        /* reserve and fill IE */

        pos = skb_put(skb, sizeof(struct ieee80211_ht_cap) + 2);
        *pos++ = WLAN_EID_HT_CAPABILITY;
        *pos++ = sizeof(struct ieee80211_ht_cap);
        memset(pos, 0, sizeof(struct ieee80211_ht_cap));

        /* capability flags */
        tmp = cpu_to_le16(cap);
        memcpy(pos, &tmp, sizeof(u16));
        pos += sizeof(u16);

        /* AMPDU parameters */
        *pos++ = sband->ht_cap.ampdu_factor |
                 (sband->ht_cap.ampdu_density <<
                        IEEE80211_HT_AMPDU_PARM_DENSITY_SHIFT);

        /* MCS set */
        memcpy(pos, &sband->ht_cap.mcs, sizeof(sband->ht_cap.mcs));
        pos += sizeof(sband->ht_cap.mcs);

        /* extended capabilities */
        pos += sizeof(__le16);

        /* BF capabilities */
        pos += sizeof(__le32);

        /* antenna selection */
        pos += sizeof(u8);
}

static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata,
                                 struct ieee80211_work *wk)
{
        struct ieee80211_local *local = sdata->local;
        struct sk_buff *skb;
        struct ieee80211_mgmt *mgmt;
        u8 *pos, qos_info;
        size_t offset = 0, noffset;
        int i, count, rates_len, supp_rates_len;
        u16 capab;
        struct ieee80211_supported_band *sband;
        u32 rates = 0;

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

        if (wk->assoc.supp_rates_len) {
                /*
                 * Get all rates supported by the device and the AP as
                 * some APs don't like getting a superset of their rates
                 * in the association request (e.g. D-Link DAP 1353 in
                 * b-only mode)...
                 */
                rates_len = ieee80211_compatible_rates(wk->assoc.supp_rates,
                                                       wk->assoc.supp_rates_len,
                                                       sband, &rates);
        } else {
                /*
                 * In case AP not provide any supported rates information
                 * before association, we send information element(s) with
                 * all rates that we support.
                 */
                rates = ~0;
                rates_len = sband->n_bitrates;
        }

        skb = alloc_skb(local->hw.extra_tx_headroom +
                        sizeof(*mgmt) + /* bit too much but doesn't matter */
                        2 + wk->assoc.ssid_len + /* SSID */
                        4 + rates_len + /* (extended) rates */
                        4 + /* power capability */
                        2 + 2 * sband->n_channels + /* supported channels */
                        2 + sizeof(struct ieee80211_ht_cap) + /* HT */
                        wk->ie_len + /* extra IEs */
                        9, /* WMM */
                        GFP_KERNEL);
        if (!skb)
                return;

        skb_reserve(skb, local->hw.extra_tx_headroom);

        capab = WLAN_CAPABILITY_ESS;

        if (sband->band == IEEE80211_BAND_2GHZ) {
                if (!(local->hw.flags & IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE))
                        capab |= WLAN_CAPABILITY_SHORT_SLOT_TIME;
                if (!(local->hw.flags & IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE))
                        capab |= WLAN_CAPABILITY_SHORT_PREAMBLE;
        }

        if (wk->assoc.capability & WLAN_CAPABILITY_PRIVACY)
                capab |= WLAN_CAPABILITY_PRIVACY;

        if ((wk->assoc.capability & WLAN_CAPABILITY_SPECTRUM_MGMT) &&
            (local->hw.flags & IEEE80211_HW_SPECTRUM_MGMT))
                capab |= WLAN_CAPABILITY_SPECTRUM_MGMT;

        mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
        memset(mgmt, 0, 24);
        memcpy(mgmt->da, wk->filter_ta, ETH_ALEN);
        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(mgmt->bssid, wk->filter_ta, ETH_ALEN);

        if (!is_zero_ether_addr(wk->assoc.prev_bssid)) {
                skb_put(skb, 10);
                mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                                  IEEE80211_STYPE_REASSOC_REQ);
                mgmt->u.reassoc_req.capab_info = cpu_to_le16(capab);
                mgmt->u.reassoc_req.listen_interval =
                                cpu_to_le16(local->hw.conf.listen_interval);
                memcpy(mgmt->u.reassoc_req.current_ap, wk->assoc.prev_bssid,
                       ETH_ALEN);
        } else {
                skb_put(skb, 4);
                mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                                  IEEE80211_STYPE_ASSOC_REQ);
                mgmt->u.assoc_req.capab_info = cpu_to_le16(capab);
                mgmt->u.assoc_req.listen_interval =
                                cpu_to_le16(local->hw.conf.listen_interval);
        }

        /* SSID */
        pos = skb_put(skb, 2 + wk->assoc.ssid_len);
        *pos++ = WLAN_EID_SSID;
        *pos++ = wk->assoc.ssid_len;
        memcpy(pos, wk->assoc.ssid, wk->assoc.ssid_len);

        /* add all rates which were marked to be used above */
        supp_rates_len = rates_len;
        if (supp_rates_len > 8)
                supp_rates_len = 8;

        pos = skb_put(skb, supp_rates_len + 2);
        *pos++ = WLAN_EID_SUPP_RATES;
        *pos++ = supp_rates_len;

        count = 0;
        for (i = 0; i < sband->n_bitrates; i++) {
                if (BIT(i) & rates) {
                        int rate = sband->bitrates[i].bitrate;
                        *pos++ = (u8) (rate / 5);
                        if (++count == 8)
                                break;
                }
        }

        if (rates_len > count) {
                pos = skb_put(skb, rates_len - count + 2);
                *pos++ = WLAN_EID_EXT_SUPP_RATES;
                *pos++ = rates_len - count;

                for (i++; i < sband->n_bitrates; i++) {
                        if (BIT(i) & rates) {
                                int rate = sband->bitrates[i].bitrate;
                                *pos++ = (u8) (rate / 5);
                        }
                }
        }

        if (capab & WLAN_CAPABILITY_SPECTRUM_MGMT) {
                /* 1. power capabilities */
                pos = skb_put(skb, 4);
                *pos++ = WLAN_EID_PWR_CAPABILITY;
                *pos++ = 2;
                *pos++ = 0; /* min tx power */
                *pos++ = wk->chan->max_power; /* max tx power */

                /* 2. supported channels */
                /* TODO: get this in reg domain format */
                pos = skb_put(skb, 2 * sband->n_channels + 2);
                *pos++ = WLAN_EID_SUPPORTED_CHANNELS;
                *pos++ = 2 * sband->n_channels;
                for (i = 0; i < sband->n_channels; i++) {
                        *pos++ = ieee80211_frequency_to_channel(
                                        sband->channels[i].center_freq);
                        *pos++ = 1; /* one channel in the subband*/
                }
        }

        /* if present, add any custom IEs that go before HT */
        if (wk->ie_len && wk->ie) {
                static const u8 before_ht[] = {
                        WLAN_EID_SSID,
                        WLAN_EID_SUPP_RATES,
                        WLAN_EID_EXT_SUPP_RATES,
                        WLAN_EID_PWR_CAPABILITY,
                        WLAN_EID_SUPPORTED_CHANNELS,
                        WLAN_EID_RSN,
                        WLAN_EID_QOS_CAPA,
                        WLAN_EID_RRM_ENABLED_CAPABILITIES,
                        WLAN_EID_MOBILITY_DOMAIN,
                        WLAN_EID_SUPPORTED_REGULATORY_CLASSES,
                };
                noffset = ieee80211_ie_split(wk->ie, wk->ie_len,
                                             before_ht, ARRAY_SIZE(before_ht),
                                             offset);
                pos = skb_put(skb, noffset - offset);
                memcpy(pos, wk->ie + offset, noffset - offset);
                offset = noffset;
        }

        if (wk->assoc.use_11n && wk->assoc.wmm_used &&
            local->hw.queues >= 4)
                ieee80211_add_ht_ie(skb, wk->assoc.ht_information_ie,
                                    sband, wk->chan, wk->assoc.smps);

        /* if present, add any custom non-vendor IEs that go after HT */
        if (wk->ie_len && wk->ie) {
                noffset = ieee80211_ie_split_vendor(wk->ie, wk->ie_len,
                                                    offset);
                pos = skb_put(skb, noffset - offset);
                memcpy(pos, wk->ie + offset, noffset - offset);
                offset = noffset;
        }

        if (wk->assoc.wmm_used && local->hw.queues >= 4) {
                if (wk->assoc.uapsd_used) {
                        qos_info = local->uapsd_queues;
                        qos_info |= (local->uapsd_max_sp_len <<
                                     IEEE80211_WMM_IE_STA_QOSINFO_SP_SHIFT);
                } else {
                        qos_info = 0;
                }

                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++ = qos_info;
        }

        /* add any remaining custom (i.e. vendor specific here) IEs */
        if (wk->ie_len && wk->ie) {
                noffset = wk->ie_len;
                pos = skb_put(skb, noffset - offset);
                memcpy(pos, wk->ie + offset, noffset - offset);
        }

        IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
        ieee80211_tx_skb(sdata, skb);
}

static void ieee80211_remove_auth_bss(struct ieee80211_local *local,
                                      struct ieee80211_work *wk)
{
        struct cfg80211_bss *cbss;
        u16 capa_val = WLAN_CAPABILITY_ESS;

        if (wk->probe_auth.privacy)
                capa_val |= WLAN_CAPABILITY_PRIVACY;

        cbss = cfg80211_get_bss(local->hw.wiphy, wk->chan, wk->filter_ta,
                                wk->probe_auth.ssid, wk->probe_auth.ssid_len,
                                WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_PRIVACY,
                                capa_val);
        if (!cbss)
                return;

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

static enum work_action __must_check
ieee80211_direct_probe(struct ieee80211_work *wk)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;

        if (!wk->probe_auth.synced) {
                int ret = drv_tx_sync(local, sdata, wk->filter_ta,
                                      IEEE80211_TX_SYNC_AUTH);
                if (ret)
                        return WORK_ACT_TIMEOUT;
        }
        wk->probe_auth.synced = true;

        wk->probe_auth.tries++;
        if (wk->probe_auth.tries > IEEE80211_AUTH_MAX_TRIES) {
                printk(KERN_DEBUG "%s: direct probe to %pM timed out\n",
                       sdata->name, wk->filter_ta);

                /*
                 * Most likely AP is not in the range so remove the
                 * bss struct for that AP.
                 */
                ieee80211_remove_auth_bss(local, wk);

                return WORK_ACT_TIMEOUT;
        }

        printk(KERN_DEBUG "%s: direct probe to %pM (try %d/%i)\n",
               sdata->name, wk->filter_ta, wk->probe_auth.tries,
               IEEE80211_AUTH_MAX_TRIES);

        /*
         * Direct probe is sent to broadcast address as some APs
         * will not answer to direct packet in unassociated state.
         */
        ieee80211_send_probe_req(sdata, NULL, wk->probe_auth.ssid,
                                 wk->probe_auth.ssid_len, NULL, 0,
                                 (u32) -1, true, false);

        wk->timeout = jiffies + IEEE80211_AUTH_TIMEOUT;
        run_again(local, wk->timeout);

        return WORK_ACT_NONE;
}


static enum work_action __must_check
ieee80211_authenticate(struct ieee80211_work *wk)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;

        if (!wk->probe_auth.synced) {
                int ret = drv_tx_sync(local, sdata, wk->filter_ta,
                                      IEEE80211_TX_SYNC_AUTH);
                if (ret)
                        return WORK_ACT_TIMEOUT;
        }
        wk->probe_auth.synced = true;

        wk->probe_auth.tries++;
        if (wk->probe_auth.tries > IEEE80211_AUTH_MAX_TRIES) {
                printk(KERN_DEBUG "%s: authentication with %pM"
                       " timed out\n", sdata->name, wk->filter_ta);

                /*
                 * Most likely AP is not in the range so remove the
                 * bss struct for that AP.
                 */
                ieee80211_remove_auth_bss(local, wk);

                return WORK_ACT_TIMEOUT;
        }

        printk(KERN_DEBUG "%s: authenticate with %pM (try %d)\n",
               sdata->name, wk->filter_ta, wk->probe_auth.tries);

        ieee80211_send_auth(sdata, 1, wk->probe_auth.algorithm, wk->ie,
                            wk->ie_len, wk->filter_ta, NULL, 0, 0);
        wk->probe_auth.transaction = 2;

        wk->timeout = jiffies + IEEE80211_AUTH_TIMEOUT;
        run_again(local, wk->timeout);

        return WORK_ACT_NONE;
}

static enum work_action __must_check
ieee80211_associate(struct ieee80211_work *wk)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;

        if (!wk->assoc.synced) {
                int ret = drv_tx_sync(local, sdata, wk->filter_ta,
                                      IEEE80211_TX_SYNC_ASSOC);
                if (ret)
                        return WORK_ACT_TIMEOUT;
        }
        wk->assoc.synced = true;

        wk->assoc.tries++;
        if (wk->assoc.tries > IEEE80211_ASSOC_MAX_TRIES) {
                printk(KERN_DEBUG "%s: association with %pM"
                       " timed out\n",
                       sdata->name, wk->filter_ta);

                /*
                 * Most likely AP is not in the range so remove the
                 * bss struct for that AP.
                 */
                if (wk->assoc.bss)
                        cfg80211_unlink_bss(local->hw.wiphy, wk->assoc.bss);

                return WORK_ACT_TIMEOUT;
        }

        printk(KERN_DEBUG "%s: associate with %pM (try %d)\n",
               sdata->name, wk->filter_ta, wk->assoc.tries);
        ieee80211_send_assoc(sdata, wk);

        wk->timeout = jiffies + IEEE80211_ASSOC_TIMEOUT;
        run_again(local, wk->timeout);

        return WORK_ACT_NONE;
}

static enum work_action __must_check
ieee80211_remain_on_channel_timeout(struct ieee80211_work *wk)
{
        /*
         * First time we run, do nothing -- the generic code will
         * have switched to the right channel etc.
         */
        if (!wk->started) {
                wk->timeout = jiffies + msecs_to_jiffies(wk->remain.duration);

                cfg80211_ready_on_channel(wk->sdata->dev, (unsigned long) wk,
                                          wk->chan, wk->chan_type,
                                          wk->remain.duration, GFP_KERNEL);

                return WORK_ACT_NONE;
        }

        return WORK_ACT_TIMEOUT;
}

static enum work_action __must_check
ieee80211_offchannel_tx(struct ieee80211_work *wk)
{
        if (!wk->started) {
                wk->timeout = jiffies + msecs_to_jiffies(wk->offchan_tx.wait);

                /*
                 * After this, offchan_tx.frame remains but now is no
                 * longer a valid pointer -- we still need it as the
                 * cookie for canceling this work/status matching.
                 */
                ieee80211_tx_skb(wk->sdata, wk->offchan_tx.frame);

                return WORK_ACT_NONE;
        }

        return WORK_ACT_TIMEOUT;
}

static enum work_action __must_check
ieee80211_assoc_beacon_wait(struct ieee80211_work *wk)
{
        if (wk->started)
                return WORK_ACT_TIMEOUT;

        /*
         * Wait up to one beacon interval ...
         * should this be more if we miss one?
         */
        printk(KERN_DEBUG "%s: waiting for beacon from %pM\n",
               wk->sdata->name, wk->filter_ta);
        wk->timeout = TU_TO_EXP_TIME(wk->assoc.bss->beacon_interval);
        return WORK_ACT_NONE;
}

static void ieee80211_auth_challenge(struct ieee80211_work *wk,
                                     struct ieee80211_mgmt *mgmt,
                                     size_t len)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        u8 *pos;
        struct ieee802_11_elems elems;

        pos = mgmt->u.auth.variable;
        ieee802_11_parse_elems(pos, len - (pos - (u8 *) mgmt), &elems);
        if (!elems.challenge)
                return;
        ieee80211_send_auth(sdata, 3, wk->probe_auth.algorithm,
                            elems.challenge - 2, elems.challenge_len + 2,
                            wk->filter_ta, wk->probe_auth.key,
                            wk->probe_auth.key_len, wk->probe_auth.key_idx);
        wk->probe_auth.transaction = 4;
}

static enum work_action __must_check
ieee80211_rx_mgmt_auth(struct ieee80211_work *wk,
                       struct ieee80211_mgmt *mgmt, size_t len)
{
        u16 auth_alg, auth_transaction, status_code;

        if (wk->type != IEEE80211_WORK_AUTH)
                return WORK_ACT_MISMATCH;

        if (len < 24 + 6)
                return WORK_ACT_NONE;

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

        if (auth_alg != wk->probe_auth.algorithm ||
            auth_transaction != wk->probe_auth.transaction)
                return WORK_ACT_NONE;

        if (status_code != WLAN_STATUS_SUCCESS) {
                printk(KERN_DEBUG "%s: %pM denied authentication (status %d)\n",
                       wk->sdata->name, mgmt->sa, status_code);
                return WORK_ACT_DONE;
        }

        switch (wk->probe_auth.algorithm) {
        case WLAN_AUTH_OPEN:
        case WLAN_AUTH_LEAP:
        case WLAN_AUTH_FT:
                break;
        case WLAN_AUTH_SHARED_KEY:
                if (wk->probe_auth.transaction != 4) {
                        ieee80211_auth_challenge(wk, mgmt, len);
                        /* need another frame */
                        return WORK_ACT_NONE;
                }
                break;
        default:
                WARN_ON(1);
                return WORK_ACT_NONE;
        }

        printk(KERN_DEBUG "%s: authenticated\n", wk->sdata->name);
        return WORK_ACT_DONE;
}

static enum work_action __must_check
ieee80211_rx_mgmt_assoc_resp(struct ieee80211_work *wk,
                             struct ieee80211_mgmt *mgmt, size_t len,
                             bool reassoc)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;
        u16 capab_info, status_code, aid;
        struct ieee802_11_elems elems;
        u8 *pos;

        if (wk->type != IEEE80211_WORK_ASSOC)
                return WORK_ACT_MISMATCH;

        /*
         * AssocResp and ReassocResp have identical structure, so process both
         * of them in this function.
         */

        if (len < 24 + 6)
                return WORK_ACT_NONE;

        capab_info = le16_to_cpu(mgmt->u.assoc_resp.capab_info);
        status_code = le16_to_cpu(mgmt->u.assoc_resp.status_code);
        aid = le16_to_cpu(mgmt->u.assoc_resp.aid);

        printk(KERN_DEBUG "%s: RX %sssocResp from %pM (capab=0x%x "
               "status=%d aid=%d)\n",
               sdata->name, reassoc ? "Rea" : "A", mgmt->sa,
               capab_info, status_code, (u16)(aid & ~(BIT(15) | BIT(14))));

        pos = mgmt->u.assoc_resp.variable;
        ieee802_11_parse_elems(pos, len - (pos - (u8 *) mgmt), &elems);

        if (status_code == WLAN_STATUS_ASSOC_REJECTED_TEMPORARILY &&
            elems.timeout_int && elems.timeout_int_len == 5 &&
            elems.timeout_int[0] == WLAN_TIMEOUT_ASSOC_COMEBACK) {
                u32 tu, ms;
                tu = get_unaligned_le32(elems.timeout_int + 1);
                ms = tu * 1024 / 1000;
                printk(KERN_DEBUG "%s: %pM rejected association temporarily; "
                       "comeback duration %u TU (%u ms)\n",
                       sdata->name, mgmt->sa, tu, ms);
                wk->timeout = jiffies + msecs_to_jiffies(ms);
                if (ms > IEEE80211_ASSOC_TIMEOUT)
                        run_again(local, wk->timeout);
                return WORK_ACT_NONE;
        }

        if (status_code != WLAN_STATUS_SUCCESS)
                printk(KERN_DEBUG "%s: %pM denied association (code=%d)\n",
                       sdata->name, mgmt->sa, status_code);
        else
                printk(KERN_DEBUG "%s: associated\n", sdata->name);

        return WORK_ACT_DONE;
}

static enum work_action __must_check
ieee80211_rx_mgmt_probe_resp(struct ieee80211_work *wk,
                             struct ieee80211_mgmt *mgmt, size_t len,
                             struct ieee80211_rx_status *rx_status)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;
        size_t baselen;

        ASSERT_WORK_MTX(local);

        if (wk->type != IEEE80211_WORK_DIRECT_PROBE)
                return WORK_ACT_MISMATCH;

        if (len < 24 + 12)
                return WORK_ACT_NONE;

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

        printk(KERN_DEBUG "%s: direct probe responded\n", sdata->name);
        return WORK_ACT_DONE;
}

static enum work_action __must_check
ieee80211_rx_mgmt_beacon(struct ieee80211_work *wk,
                         struct ieee80211_mgmt *mgmt, size_t len)
{
        struct ieee80211_sub_if_data *sdata = wk->sdata;
        struct ieee80211_local *local = sdata->local;

        ASSERT_WORK_MTX(local);

        if (wk->type != IEEE80211_WORK_ASSOC_BEACON_WAIT)
                return WORK_ACT_MISMATCH;

        if (len < 24 + 12)
                return WORK_ACT_NONE;

        printk(KERN_DEBUG "%s: beacon received\n", sdata->name);
        return WORK_ACT_DONE;
}

static void ieee80211_work_rx_queued_mgmt(struct ieee80211_local *local,
                                          struct sk_buff *skb)
{
        struct ieee80211_rx_status *rx_status;
        struct ieee80211_mgmt *mgmt;
        struct ieee80211_work *wk;
        enum work_action rma = WORK_ACT_NONE;
        u16 fc;

        rx_status = (struct ieee80211_rx_status *) skb->cb;
        mgmt = (struct ieee80211_mgmt *) skb->data;
        fc = le16_to_cpu(mgmt->frame_control);

        mutex_lock(&local->mtx);

        list_for_each_entry(wk, &local->work_list, list) {
                const u8 *bssid = NULL;

                switch (wk->type) {
                case IEEE80211_WORK_DIRECT_PROBE:
                case IEEE80211_WORK_AUTH:
                case IEEE80211_WORK_ASSOC:
                case IEEE80211_WORK_ASSOC_BEACON_WAIT:
                        bssid = wk->filter_ta;
                        break;
                default:
                        continue;
                }

                /*
                 * Before queuing, we already verified mgmt->sa,
                 * so this is needed just for matching.
                 */
                if (compare_ether_addr(bssid, mgmt->bssid))
                        continue;

                switch (fc & IEEE80211_FCTL_STYPE) {
                case IEEE80211_STYPE_BEACON:
                        rma = ieee80211_rx_mgmt_beacon(wk, mgmt, skb->len);
                        break;
                case IEEE80211_STYPE_PROBE_RESP:
                        rma = ieee80211_rx_mgmt_probe_resp(wk, mgmt, skb->len,
                                                           rx_status);
                        break;
                case IEEE80211_STYPE_AUTH:
                        rma = ieee80211_rx_mgmt_auth(wk, mgmt, skb->len);
                        break;
                case IEEE80211_STYPE_ASSOC_RESP:
                        rma = ieee80211_rx_mgmt_assoc_resp(wk, mgmt,
                                                           skb->len, false);
                        break;
                case IEEE80211_STYPE_REASSOC_RESP:
                        rma = ieee80211_rx_mgmt_assoc_resp(wk, mgmt,
                                                           skb->len, true);
                        break;
                default:
                        WARN_ON(1);
                        rma = WORK_ACT_NONE;
                }

                /*
                 * We've either received an unexpected frame, or we have
                 * multiple work items and need to match the frame to the
                 * right one.
                 */
                if (rma == WORK_ACT_MISMATCH)
                        continue;

                /*
                 * We've processed this frame for that work, so it can't
                 * belong to another work struct.
                 * NB: this is also required for correctness for 'rma'!
                 */
                break;
        }

        switch (rma) {
        case WORK_ACT_MISMATCH:
                /* ignore this unmatched frame */
                break;
        case WORK_ACT_NONE:
                break;
        case WORK_ACT_DONE:
                list_del_rcu(&wk->list);
                break;
        default:
                WARN(1, "unexpected: %d", rma);
        }

        mutex_unlock(&local->mtx);

        if (rma != WORK_ACT_DONE)
                goto out;

        switch (wk->done(wk, skb)) {
        case WORK_DONE_DESTROY:
                free_work(wk);
                break;
        case WORK_DONE_REQUEUE:
                synchronize_rcu();
                wk->started = false; /* restart */
                mutex_lock(&local->mtx);
                list_add_tail(&wk->list, &local->work_list);
                mutex_unlock(&local->mtx);
        }

 out:
        kfree_skb(skb);
}

static bool ieee80211_work_ct_coexists(enum nl80211_channel_type wk_ct,
                                       enum nl80211_channel_type oper_ct)
{
        switch (wk_ct) {
        case NL80211_CHAN_NO_HT:
                return true;
        case NL80211_CHAN_HT20:
                if (oper_ct != NL80211_CHAN_NO_HT)
                        return true;
                return false;
        case NL80211_CHAN_HT40MINUS:
        case NL80211_CHAN_HT40PLUS:
                return (wk_ct == oper_ct);
        }
        WARN_ON(1); /* shouldn't get here */
        return false;
}

static void ieee80211_work_timer(unsigned long data)
{
        struct ieee80211_local *local = (void *) data;

        if (local->quiescing)
                return;

        ieee80211_queue_work(&local->hw, &local->work_work);
}

static void ieee80211_work_work(struct work_struct *work)
{
        struct ieee80211_local *local =
                container_of(work, struct ieee80211_local, work_work);
        struct sk_buff *skb;
        struct ieee80211_work *wk, *tmp;
        LIST_HEAD(free_work);
        enum work_action rma;
        bool remain_off_channel = false;

        if (local->scanning)
                return;

        /*
         * ieee80211_queue_work() should have picked up most cases,
         * here we'll pick the rest.
         */
        if (WARN(local->suspended, "work scheduled while going to suspend\n"))
                return;

        /* first process frames to avoid timing out while a frame is pending */
        while ((skb = skb_dequeue(&local->work_skb_queue)))
                ieee80211_work_rx_queued_mgmt(local, skb);

        mutex_lock(&local->mtx);

        ieee80211_recalc_idle(local);

        list_for_each_entry_safe(wk, tmp, &local->work_list, list) {
                bool started = wk->started;

                /* mark work as started if it's on the current off-channel */
                if (!started && local->tmp_channel &&
                    wk->chan == local->tmp_channel &&
                    wk->chan_type == local->tmp_channel_type) {
                        started = true;
                        wk->timeout = jiffies;
                }

                if (!started && !local->tmp_channel) {
                        /*
                         * TODO: could optimize this by leaving the
                         *       station vifs in awake mode if they
                         *       happen to be on the same channel as
                         *       the requested channel
                         */
                        ieee80211_offchannel_stop_beaconing(local);
                        ieee80211_offchannel_stop_station(local);

                        local->tmp_channel = wk->chan;
                        local->tmp_channel_type = wk->chan_type;
                        ieee80211_hw_config(local, 0);
                        started = true;
                        wk->timeout = jiffies;
                }

                /* don't try to work with items that aren't started */
                if (!started)
                        continue;

                if (time_is_after_jiffies(wk->timeout)) {
                        /*
                         * This work item isn't supposed to be worked on
                         * right now, but take care to adjust the timer
                         * properly.
                         */
                        run_again(local, wk->timeout);
                        continue;
                }

                switch (wk->type) {
                default:
                        WARN_ON(1);
                        /* nothing */
                        rma = WORK_ACT_NONE;
                        break;
                case IEEE80211_WORK_ABORT:
                        rma = WORK_ACT_TIMEOUT;
                        break;
                case IEEE80211_WORK_DIRECT_PROBE:
                        rma = ieee80211_direct_probe(wk);
                        break;
                case IEEE80211_WORK_AUTH:
                        rma = ieee80211_authenticate(wk);
                        break;
                case IEEE80211_WORK_ASSOC:
                        rma = ieee80211_associate(wk);
                        break;
                case IEEE80211_WORK_REMAIN_ON_CHANNEL:
                        rma = ieee80211_remain_on_channel_timeout(wk);
                        break;
                case IEEE80211_WORK_OFFCHANNEL_TX:
                        rma = ieee80211_offchannel_tx(wk);
                        break;
                case IEEE80211_WORK_ASSOC_BEACON_WAIT:
                        rma = ieee80211_assoc_beacon_wait(wk);
                        break;
                }

                wk->started = started;

                switch (rma) {
                case WORK_ACT_NONE:
                        /* might have changed the timeout */
                        run_again(local, wk->timeout);
                        break;
                case WORK_ACT_TIMEOUT:
                        list_del_rcu(&wk->list);
                        synchronize_rcu();
                        list_add(&wk->list, &free_work);
                        break;
                default:
                        WARN(1, "unexpected: %d", rma);
                }
        }

        list_for_each_entry(wk, &local->work_list, list) {
                if (!wk->started)
                        continue;
                if (wk->chan != local->tmp_channel)
                        continue;
                if (!ieee80211_work_ct_coexists(wk->chan_type,
                                                local->tmp_channel_type))
                        continue;
                remain_off_channel = true;
        }

        if (!remain_off_channel && local->tmp_channel) {
                local->tmp_channel = NULL;
                /* If tmp_channel wasn't operating channel, then
                 * we need to go back on-channel.
                 * NOTE:  If we can ever be here while scannning,
                 * or if the hw_config() channel config logic changes,
                 * then we may need to do a more thorough check to see if
                 * we still need to do a hardware config.  Currently,
                 * we cannot be here while scanning, however.
                 */
                ieee80211_hw_config(local, 0);

                /* At the least, we need to disable offchannel_ps,
                 * so just go ahead and run the entire offchannel
                 * return logic here.  We *could* skip enabling
                 * beaconing if we were already on-oper-channel
                 * as a future optimization.
                 */
                ieee80211_offchannel_return(local, true);

                /* give connection some time to breathe */
                run_again(local, jiffies + HZ/2);
        }

        if (list_empty(&local->work_list) && local->scan_req &&
            !local->scanning)
                ieee80211_queue_delayed_work(&local->hw,
                                             &local->scan_work,
                                             round_jiffies_relative(0));

        ieee80211_recalc_idle(local);

        mutex_unlock(&local->mtx);

        list_for_each_entry_safe(wk, tmp, &free_work, list) {
                wk->done(wk, NULL);
                list_del(&wk->list);
                kfree(wk);
        }
}

void ieee80211_add_work(struct ieee80211_work *wk)
{
        struct ieee80211_local *local;

        if (WARN_ON(!wk->chan))
                return;

        if (WARN_ON(!wk->sdata))
                return;

        if (WARN_ON(!wk->done))
                return;

        if (WARN_ON(!ieee80211_sdata_running(wk->sdata)))
                return;

        wk->started = false;

        local = wk->sdata->local;
        mutex_lock(&local->mtx);
        list_add_tail(&wk->list, &local->work_list);
        mutex_unlock(&local->mtx);

        ieee80211_queue_work(&local->hw, &local->work_work);
}

void ieee80211_work_init(struct ieee80211_local *local)
{
        INIT_LIST_HEAD(&local->work_list);
        setup_timer(&local->work_timer, ieee80211_work_timer,
                    (unsigned long)local);
        INIT_WORK(&local->work_work, ieee80211_work_work);
        skb_queue_head_init(&local->work_skb_queue);
}

void ieee80211_work_purge(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_work *wk;
        bool cleanup = false;

        mutex_lock(&local->mtx);
        list_for_each_entry(wk, &local->work_list, list) {
                if (wk->sdata != sdata)
                        continue;
                cleanup = true;
                wk->type = IEEE80211_WORK_ABORT;
                wk->started = true;
                wk->timeout = jiffies;
        }
        mutex_unlock(&local->mtx);

        /* run cleanups etc. */
        if (cleanup)
                ieee80211_work_work(&local->work_work);

        mutex_lock(&local->mtx);
        list_for_each_entry(wk, &local->work_list, list) {
                if (wk->sdata != sdata)
                        continue;
                WARN_ON(1);
                break;
        }
        mutex_unlock(&local->mtx);
}

ieee80211_rx_result ieee80211_work_rx_mgmt(struct ieee80211_sub_if_data *sdata,
                                           struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_mgmt *mgmt;
        struct ieee80211_work *wk;
        u16 fc;

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

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

        list_for_each_entry_rcu(wk, &local->work_list, list) {
                if (sdata != wk->sdata)
                        continue;
                if (compare_ether_addr(wk->filter_ta, mgmt->sa))
                        continue;
                if (compare_ether_addr(wk->filter_ta, mgmt->bssid))
                        continue;

                switch (fc & IEEE80211_FCTL_STYPE) {
                case IEEE80211_STYPE_AUTH:
                case IEEE80211_STYPE_PROBE_RESP:
                case IEEE80211_STYPE_ASSOC_RESP:
                case IEEE80211_STYPE_REASSOC_RESP:
                case IEEE80211_STYPE_BEACON:
                        skb_queue_tail(&local->work_skb_queue, skb);
                        ieee80211_queue_work(&local->hw, &local->work_work);
                        return RX_QUEUED;
                }
        }

        return RX_CONTINUE;
}

static enum work_done_result ieee80211_remain_done(struct ieee80211_work *wk,
                                                   struct sk_buff *skb)
{
        /*
         * We are done serving the remain-on-channel command.
         */
        cfg80211_remain_on_channel_expired(wk->sdata->dev, (unsigned long) wk,
                                           wk->chan, wk->chan_type,
                                           GFP_KERNEL);

        return WORK_DONE_DESTROY;
}

int ieee80211_wk_remain_on_channel(struct ieee80211_sub_if_data *sdata,
                                   struct ieee80211_channel *chan,
                                   enum nl80211_channel_type channel_type,
                                   unsigned int duration, u64 *cookie)
{
        struct ieee80211_work *wk;

        wk = kzalloc(sizeof(*wk), GFP_KERNEL);
        if (!wk)
                return -ENOMEM;

        wk->type = IEEE80211_WORK_REMAIN_ON_CHANNEL;
        wk->chan = chan;
        wk->chan_type = channel_type;
        wk->sdata = sdata;
        wk->done = ieee80211_remain_done;

        wk->remain.duration = duration;

        *cookie = (unsigned long) wk;

        ieee80211_add_work(wk);

        return 0;
}

int ieee80211_wk_cancel_remain_on_channel(struct ieee80211_sub_if_data *sdata,
                                          u64 cookie)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_work *wk, *tmp;
        bool found = false;

        mutex_lock(&local->mtx);
        list_for_each_entry_safe(wk, tmp, &local->work_list, list) {
                if ((unsigned long) wk == cookie) {
                        wk->timeout = jiffies;
                        found = true;
                        break;
                }
        }
        mutex_unlock(&local->mtx);

        if (!found)
                return -ENOENT;

        ieee80211_queue_work(&local->hw, &local->work_work);

        return 0;
}