/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007-2008  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/if_ether.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "debugfs_key.h"
#include "aes_ccm.h"
#include "aes_cmac.h"


/**
 * DOC: Key handling basics
 *
 * Key handling in mac80211 is done based on per-interface (sub_if_data)
 * keys and per-station keys. Since each station belongs to an interface,
 * each station key also belongs to that interface.
 *
 * Hardware acceleration is done on a best-effort basis for algorithms
 * that are implemented in software,  for each key the hardware is asked
 * to enable that key for offloading but if it cannot do that the key is
 * simply kept for software encryption (unless it is for an algorithm
 * that isn't implemented in software).
 * There is currently no way of knowing whether a key is handled in SW
 * or HW except by looking into debugfs.
 *
 * All key management is internally protected by a mutex. Within all
 * other parts of mac80211, key references are, just as STA structure
 * references, protected by RCU. Note, however, that some things are
 * unprotected, namely the key->sta dereferences within the hardware
 * acceleration functions. This means that sta_info_destroy() must
 * remove the key which waits for an RCU grace period.
 */

static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

static void assert_key_lock(struct ieee80211_local *local)
{
        lockdep_assert_held(&local->key_mtx);
}

static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
{
        if (key->sta)
                return &key->sta->sta;

        return NULL;
}

static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
{
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_sta *sta;
        int ret;

        might_sleep();

        if (!key->local->ops->set_key)
                goto out_unsupported;

        assert_key_lock(key->local);

        sta = get_sta_for_key(key);

        /*
         * If this is a per-STA GTK, check if it
         * is supported; if not, return.
         */
        if (sta && !(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE) &&
            !(key->local->hw.flags & IEEE80211_HW_SUPPORTS_PER_STA_GTK))
                goto out_unsupported;

        sdata = key->sdata;
        if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
                /*
                 * The driver doesn't know anything about VLAN interfaces.
                 * Hence, don't send GTKs for VLAN interfaces to the driver.
                 */
                if (!(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE))
                        goto out_unsupported;
                sdata = container_of(sdata->bss,
                                     struct ieee80211_sub_if_data,
                                     u.ap);
        }

        ret = drv_set_key(key->local, SET_KEY, sdata, sta, &key->conf);

        if (!ret) {
                key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
                return 0;
        }

        if (ret != -ENOSPC && ret != -EOPNOTSUPP)
                wiphy_err(key->local->hw.wiphy,
                          "failed to set key (%d, %pM) to hardware (%d)\n",
                          key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);

 out_unsupported:
        switch (key->conf.cipher) {
        case WLAN_CIPHER_SUITE_WEP40:
        case WLAN_CIPHER_SUITE_WEP104:
        case WLAN_CIPHER_SUITE_TKIP:
        case WLAN_CIPHER_SUITE_CCMP:
        case WLAN_CIPHER_SUITE_AES_CMAC:
                /* all of these we can do in software */
                return 0;
        default:
                return -EINVAL;
        }
}

static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
{
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_sta *sta;
        int ret;

        might_sleep();

        if (!key || !key->local->ops->set_key)
                return;

        assert_key_lock(key->local);

        if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
                return;

        sta = get_sta_for_key(key);
        sdata = key->sdata;

        if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                sdata = container_of(sdata->bss,
                                     struct ieee80211_sub_if_data,
                                     u.ap);

        ret = drv_set_key(key->local, DISABLE_KEY, sdata,
                          sta, &key->conf);

        if (ret)
                wiphy_err(key->local->hw.wiphy,
                          "failed to remove key (%d, %pM) from hardware (%d)\n",
                          key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);

        key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
}

void ieee80211_key_removed(struct ieee80211_key_conf *key_conf)
{
        struct ieee80211_key *key;

        key = container_of(key_conf, struct ieee80211_key, conf);

        might_sleep();
        assert_key_lock(key->local);

        key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;

        /*
         * Flush TX path to avoid attempts to use this key
         * after this function returns. Until then, drivers
         * must be prepared to handle the key.
         */
        synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ieee80211_key_removed);

static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
                                        int idx, bool uni, bool multi)
{
        struct ieee80211_key *key = NULL;

        assert_key_lock(sdata->local);

        if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
                key = sdata->keys[idx];

        if (uni)
                rcu_assign_pointer(sdata->default_unicast_key, key);
        if (multi)
                rcu_assign_pointer(sdata->default_multicast_key, key);

        ieee80211_debugfs_key_update_default(sdata);
}

void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,
                               bool uni, bool multi)
{
        mutex_lock(&sdata->local->key_mtx);
        __ieee80211_set_default_key(sdata, idx, uni, multi);
        mutex_unlock(&sdata->local->key_mtx);
}

static void
__ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
{
        struct ieee80211_key *key = NULL;

        assert_key_lock(sdata->local);

        if (idx >= NUM_DEFAULT_KEYS &&
            idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
                key = sdata->keys[idx];

        rcu_assign_pointer(sdata->default_mgmt_key, key);

        ieee80211_debugfs_key_update_default(sdata);
}

void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
                                    int idx)
{
        mutex_lock(&sdata->local->key_mtx);
        __ieee80211_set_default_mgmt_key(sdata, idx);
        mutex_unlock(&sdata->local->key_mtx);
}


static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
                                    struct sta_info *sta,
                                    bool pairwise,
                                    struct ieee80211_key *old,
                                    struct ieee80211_key *new)
{
        int idx;
        bool defunikey, defmultikey, defmgmtkey;

        if (new)
                list_add(&new->list, &sdata->key_list);

        if (sta && pairwise) {
                rcu_assign_pointer(sta->ptk, new);
        } else if (sta) {
                if (old)
                        idx = old->conf.keyidx;
                else
                        idx = new->conf.keyidx;
                rcu_assign_pointer(sta->gtk[idx], new);
        } else {
                WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);

                if (old)
                        idx = old->conf.keyidx;
                else
                        idx = new->conf.keyidx;

                defunikey = old && sdata->default_unicast_key == old;
                defmultikey = old && sdata->default_multicast_key == old;
                defmgmtkey = old && sdata->default_mgmt_key == old;

                if (defunikey && !new)
                        __ieee80211_set_default_key(sdata, -1, true, false);
                if (defmultikey && !new)
                        __ieee80211_set_default_key(sdata, -1, false, true);
                if (defmgmtkey && !new)
                        __ieee80211_set_default_mgmt_key(sdata, -1);

                rcu_assign_pointer(sdata->keys[idx], new);
                if (defunikey && new)
                        __ieee80211_set_default_key(sdata, new->conf.keyidx,
                                                    true, false);
                if (defmultikey && new)
                        __ieee80211_set_default_key(sdata, new->conf.keyidx,
                                                    false, true);
                if (defmgmtkey && new)
                        __ieee80211_set_default_mgmt_key(sdata,
                                                         new->conf.keyidx);
        }

        if (old)
                list_del(&old->list);
}

struct ieee80211_key *ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
                                          const u8 *key_data,
                                          size_t seq_len, const u8 *seq)
{
        struct ieee80211_key *key;
        int i, j, err;

        BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);

        key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
        if (!key)
                return ERR_PTR(-ENOMEM);

        /*
         * Default to software encryption; we'll later upload the
         * key to the hardware if possible.
         */
        key->conf.flags = 0;
        key->flags = 0;

        key->conf.cipher = cipher;
        key->conf.keyidx = idx;
        key->conf.keylen = key_len;
        switch (cipher) {
        case WLAN_CIPHER_SUITE_WEP40:
        case WLAN_CIPHER_SUITE_WEP104:
                key->conf.iv_len = WEP_IV_LEN;
                key->conf.icv_len = WEP_ICV_LEN;
                break;
        case WLAN_CIPHER_SUITE_TKIP:
                key->conf.iv_len = TKIP_IV_LEN;
                key->conf.icv_len = TKIP_ICV_LEN;
                if (seq) {
                        for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
                                key->u.tkip.rx[i].iv32 =
                                        get_unaligned_le32(&seq[2]);
                                key->u.tkip.rx[i].iv16 =
                                        get_unaligned_le16(seq);
                        }
                }
                break;
        case WLAN_CIPHER_SUITE_CCMP:
                key->conf.iv_len = CCMP_HDR_LEN;
                key->conf.icv_len = CCMP_MIC_LEN;
                if (seq) {
                        for (i = 0; i < NUM_RX_DATA_QUEUES + 1; i++)
                                for (j = 0; j < CCMP_PN_LEN; j++)
                                        key->u.ccmp.rx_pn[i][j] =
                                                seq[CCMP_PN_LEN - j - 1];
                }
                /*
                 * Initialize AES key state here as an optimization so that
                 * it does not need to be initialized for every packet.
                 */
                key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
                if (IS_ERR(key->u.ccmp.tfm)) {
                        err = PTR_ERR(key->u.ccmp.tfm);
                        kfree(key);
                        key = ERR_PTR(err);
                }
                break;
        case WLAN_CIPHER_SUITE_AES_CMAC:
                key->conf.iv_len = 0;
                key->conf.icv_len = sizeof(struct ieee80211_mmie);
                if (seq)
                        for (j = 0; j < 6; j++)
                                key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
                /*
                 * Initialize AES key state here as an optimization so that
                 * it does not need to be initialized for every packet.
                 */
                key->u.aes_cmac.tfm =
                        ieee80211_aes_cmac_key_setup(key_data);
                if (IS_ERR(key->u.aes_cmac.tfm)) {
                        err = PTR_ERR(key->u.aes_cmac.tfm);
                        kfree(key);
                        key = ERR_PTR(err);
                }
                break;
        }
        memcpy(key->conf.key, key_data, key_len);
        INIT_LIST_HEAD(&key->list);

        return key;
}

static void __ieee80211_key_destroy(struct ieee80211_key *key)
{
        if (!key)
                return;

        /*
         * Synchronize so the TX path can no longer be using
         * this key before we free/remove it.
         */
        synchronize_rcu();

        if (key->local)
                ieee80211_key_disable_hw_accel(key);

        if (key->conf.cipher == WLAN_CIPHER_SUITE_CCMP)
                ieee80211_aes_key_free(key->u.ccmp.tfm);
        if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC)
                ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
        if (key->local)
                ieee80211_debugfs_key_remove(key);

        kfree(key);
}

int ieee80211_key_link(struct ieee80211_key *key,
                       struct ieee80211_sub_if_data *sdata,
                       struct sta_info *sta)
{
        struct ieee80211_key *old_key;
        int idx, ret;
        bool pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;

        BUG_ON(!sdata);
        BUG_ON(!key);

        idx = key->conf.keyidx;
        key->local = sdata->local;
        key->sdata = sdata;
        key->sta = sta;

        if (sta) {
                /*
                 * some hardware cannot handle TKIP with QoS, so
                 * we indicate whether QoS could be in use.
                 */
                if (test_sta_flags(sta, WLAN_STA_WME))
                        key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
        } else {
                if (sdata->vif.type == NL80211_IFTYPE_STATION) {
                        struct sta_info *ap;

                        /*
                         * We're getting a sta pointer in, so must be under
                         * appropriate locking for sta_info_get().
                         */

                        /* same here, the AP could be using QoS */
                        ap = sta_info_get(key->sdata, key->sdata->u.mgd.bssid);
                        if (ap) {
                                if (test_sta_flags(ap, WLAN_STA_WME))
                                        key->conf.flags |=
                                                IEEE80211_KEY_FLAG_WMM_STA;
                        }
                }
        }

        mutex_lock(&sdata->local->key_mtx);

        if (sta && pairwise)
                old_key = sta->ptk;
        else if (sta)
                old_key = sta->gtk[idx];
        else
                old_key = sdata->keys[idx];

        __ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
        __ieee80211_key_destroy(old_key);

        ieee80211_debugfs_key_add(key);

        ret = ieee80211_key_enable_hw_accel(key);

        mutex_unlock(&sdata->local->key_mtx);

        return ret;
}

static void __ieee80211_key_free(struct ieee80211_key *key)
{
        /*
         * Replace key with nothingness if it was ever used.
         */
        if (key->sdata)
                __ieee80211_key_replace(key->sdata, key->sta,
                                key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
                                key, NULL);
        __ieee80211_key_destroy(key);
}

void ieee80211_key_free(struct ieee80211_local *local,
                        struct ieee80211_key *key)
{
        if (!key)
                return;

        mutex_lock(&local->key_mtx);
        __ieee80211_key_free(key);
        mutex_unlock(&local->key_mtx);
}

void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_key *key;

        ASSERT_RTNL();

        if (WARN_ON(!ieee80211_sdata_running(sdata)))
                return;

        mutex_lock(&sdata->local->key_mtx);

        list_for_each_entry(key, &sdata->key_list, list)
                ieee80211_key_enable_hw_accel(key);

        mutex_unlock(&sdata->local->key_mtx);
}

void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_key *key;

        ASSERT_RTNL();

        mutex_lock(&sdata->local->key_mtx);

        list_for_each_entry(key, &sdata->key_list, list)
                ieee80211_key_disable_hw_accel(key);

        mutex_unlock(&sdata->local->key_mtx);
}

void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_key *key, *tmp;

        mutex_lock(&sdata->local->key_mtx);

        ieee80211_debugfs_key_remove_mgmt_default(sdata);

        list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
                __ieee80211_key_free(key);

        ieee80211_debugfs_key_update_default(sdata);

        mutex_unlock(&sdata->local->key_mtx);
}