key.c

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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <[email protected]>
 * Copyright 2007-2008  Johannes Berg <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/if_ether.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "debugfs_key.h"
#include "aes_ccm.h"
#include "aes_cmac.h"


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 void increment_tailroom_need_count(struct ieee80211_sub_if_data *sdata)
{
    /*
     * When this count is zero, SKB resizing for allocating tailroom
     * for IV or MMIC is skipped. But, this check has created two race
     * cases in xmit path while transiting from zero count to one:
     *
     * 1. SKB resize was skipped because no key was added but just before
     * the xmit key is added and SW encryption kicks off.
     *
     * 2. SKB resize was skipped because all the keys were hw planted but
     * just before xmit one of the key is deleted and SW encryption kicks
     * off.
     *
     * In both the above case SW encryption will find not enough space for
     * tailroom and exits with WARN_ON. (See WARN_ONs at wpa.c)
     *
     * Solution has been explained at
     * http://mid.gmane.org/[email protected]
     */

    if (!sdata->crypto_tx_tailroom_needed_cnt++) {
        /*
         * Flush all XMIT packets currently using HW encryption or no
         * encryption at all if the count transition is from 0 -> 1.
         */
        synchronize_net();
    }
}

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

    might_sleep();

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

    assert_key_lock(key->local);

    sta = key->sta;

    /*
     * 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;

    if (sta && !sta->uploaded)
        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;
    }

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

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

        if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
              (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
              (key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
            sdata->crypto_tx_tailroom_needed_cnt--;

        WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&
            (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV));

        return 0;
    }

    if (ret != -ENOSPC && ret != -EOPNOTSUPP)
        sdata_err(sdata,
              "failed to set key (%d, %pM) to hardware (%d)\n",
              key->conf.keyidx,
              sta ? 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 sta_info *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 = key->sta;
    sdata = key->sdata;

    if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
          (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
          (key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
        increment_tailroom_need_count(sdata);

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

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

    key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
}

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 = key_mtx_dereference(sdata->local, 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 = key_mtx_dereference(sdata->local, 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_tail(&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 &&
            old == key_mtx_dereference(sdata->local,
                        sdata->default_unicast_key);
        defmultikey = old &&
            old == key_mtx_dereference(sdata->local,
                        sdata->default_multicast_key);
        defmgmtkey = old &&
            old == key_mtx_dereference(sdata->local,
                        sdata->default_mgmt_key);

        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);
            }
        }
        spin_lock_init(&key->u.tkip.txlock);
        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);
            return 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);
            return 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_net();

    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);
        key->sdata->crypto_tx_tailroom_needed_cnt--;
    }

    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;

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

    pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
    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_flag(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_flag(ap, WLAN_STA_WME))
                    key->conf.flags |=
                        IEEE80211_KEY_FLAG_WMM_STA;
            }
        }
    }

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

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

    increment_tailroom_need_count(sdata);

    __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;
}

void __ieee80211_key_free(struct ieee80211_key *key)
{
    if (!key)
        return;

    /*
     * 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)
{
    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);

    sdata->crypto_tx_tailroom_needed_cnt = 0;

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

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

void ieee80211_iter_keys(struct ieee80211_hw *hw,
             struct ieee80211_vif *vif,
             void (*iter)(struct ieee80211_hw *hw,
                      struct ieee80211_vif *vif,
                      struct ieee80211_sta *sta,
                      struct ieee80211_key_conf *key,
                      void *data),
             void *iter_data)
{
    struct ieee80211_local *local = hw_to_local(hw);
    struct ieee80211_key *key;
    struct ieee80211_sub_if_data *sdata;

    ASSERT_RTNL();

    mutex_lock(&local->key_mtx);
    if (vif) {
        sdata = vif_to_sdata(vif);
        list_for_each_entry(key, &sdata->key_list, list)
            iter(hw, &sdata->vif,
                 key->sta ? &key->sta->sta : NULL,
                 &key->conf, iter_data);
    } else {
        list_for_each_entry(sdata, &local->interfaces, list)
            list_for_each_entry(key, &sdata->key_list, list)
                iter(hw, &sdata->vif,
                     key->sta ? &key->sta->sta : NULL,
                     &key->conf, iter_data);
    }
    mutex_unlock(&local->key_mtx);
}
EXPORT_SYMBOL(ieee80211_iter_keys);

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);
}


void ieee80211_gtk_rekey_notify(struct ieee80211_vif *vif, const u8 *bssid,
                const u8 *replay_ctr, gfp_t gfp)
{
    struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);

    trace_api_gtk_rekey_notify(sdata, bssid, replay_ctr);

    cfg80211_gtk_rekey_notify(sdata->dev, bssid, replay_ctr, gfp);
}
EXPORT_SYMBOL_GPL(ieee80211_gtk_rekey_notify);

void ieee80211_get_key_tx_seq(struct ieee80211_key_conf *keyconf,
                  struct ieee80211_key_seq *seq)
{
    struct ieee80211_key *key;
    u64 pn64;

    if (WARN_ON(!(keyconf->flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
        return;

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

    switch (key->conf.cipher) {
    case WLAN_CIPHER_SUITE_TKIP:
        seq->tkip.iv32 = key->u.tkip.tx.iv32;
        seq->tkip.iv16 = key->u.tkip.tx.iv16;
        break;
    case WLAN_CIPHER_SUITE_CCMP:
        pn64 = atomic64_read(&key->u.ccmp.tx_pn);
        seq->ccmp.pn[5] = pn64;
        seq->ccmp.pn[4] = pn64 >> 8;
        seq->ccmp.pn[3] = pn64 >> 16;
        seq->ccmp.pn[2] = pn64 >> 24;
        seq->ccmp.pn[1] = pn64 >> 32;
        seq->ccmp.pn[0] = pn64 >> 40;
        break;
    case WLAN_CIPHER_SUITE_AES_CMAC:
        pn64 = atomic64_read(&key->u.aes_cmac.tx_pn);
        seq->ccmp.pn[5] = pn64;
        seq->ccmp.pn[4] = pn64 >> 8;
        seq->ccmp.pn[3] = pn64 >> 16;
        seq->ccmp.pn[2] = pn64 >> 24;
        seq->ccmp.pn[1] = pn64 >> 32;
        seq->ccmp.pn[0] = pn64 >> 40;
        break;
    default:
        WARN_ON(1);
    }
}
EXPORT_SYMBOL(ieee80211_get_key_tx_seq);

void ieee80211_get_key_rx_seq(struct ieee80211_key_conf *keyconf,
                  int tid, struct ieee80211_key_seq *seq)
{
    struct ieee80211_key *key;
    const u8 *pn;

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

    switch (key->conf.cipher) {
    case WLAN_CIPHER_SUITE_TKIP:
        if (WARN_ON(tid < 0 || tid >= NUM_RX_DATA_QUEUES))
            return;
        seq->tkip.iv32 = key->u.tkip.rx[tid].iv32;
        seq->tkip.iv16 = key->u.tkip.rx[tid].iv16;
        break;
    case WLAN_CIPHER_SUITE_CCMP:
        if (WARN_ON(tid < -1 || tid >= NUM_RX_DATA_QUEUES))
            return;
        if (tid < 0)
            pn = key->u.ccmp.rx_pn[NUM_RX_DATA_QUEUES];
        else
            pn = key->u.ccmp.rx_pn[tid];
        memcpy(seq->ccmp.pn, pn, CCMP_PN_LEN);
        break;
    case WLAN_CIPHER_SUITE_AES_CMAC:
        if (WARN_ON(tid != 0))
            return;
        pn = key->u.aes_cmac.rx_pn;
        memcpy(seq->aes_cmac.pn, pn, CMAC_PN_LEN);
        break;
    }
}
EXPORT_SYMBOL(ieee80211_get_key_rx_seq);