key.c

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/*
 * 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 <linux/export.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"


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 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/1308590980.4322.19.camel@jlt3.sipsolutions.net
         */

        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 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;

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

                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 (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
              (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
                increment_tailroom_need_count(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 = 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_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);
                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);