drm/r600: fix possible NULL pointer derefernce

[linux-2.6.git] / net / mac80211 / key.c

/*
 * 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 each key
 * that is eligible the hardware is asked to enable that key but if
 * it cannot do that they key is simply kept for software encryption.
 * There is currently no way of knowing this except by looking into
 * debugfs.
 *
 * All key operations are protected internally so you can call them at
 * any time.
 *
 * Within 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 flush the key todo
 * list.
 *
 * All the direct key list manipulation functions must not sleep because
 * they can operate on STA info structs that are protected by RCU.
 */

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

/* key mutex: used to synchronise todo runners */
static DEFINE_MUTEX(key_mutex);
static DEFINE_SPINLOCK(todo_lock);
static LIST_HEAD(todo_list);

static void key_todo(struct work_struct *work)
{
        ieee80211_key_todo();
}

static DECLARE_WORK(todo_work, key_todo);

/**
 * add_todo - add todo item for a key
 *
 * @key: key to add to do item for
 * @flag: todo flag(s)
 *
 * Must be called with IRQs or softirqs disabled.
 */
static void add_todo(struct ieee80211_key *key, u32 flag)
{
        if (!key)
                return;

        spin_lock(&todo_lock);
        key->flags |= flag;
        /*
         * Remove again if already on the list so that we move it to the end.
         */
        if (!list_empty(&key->todo))
                list_del(&key->todo);
        list_add_tail(&key->todo, &todo_list);
        schedule_work(&todo_work);
        spin_unlock(&todo_lock);
}

/**
 * ieee80211_key_lock - lock the mac80211 key operation lock
 *
 * This locks the (global) mac80211 key operation lock, all
 * key operations must be done under this lock.
 */
static void ieee80211_key_lock(void)
{
        mutex_lock(&key_mutex);
}

/**
 * ieee80211_key_unlock - unlock the mac80211 key operation lock
 */
static void ieee80211_key_unlock(void)
{
        mutex_unlock(&key_mutex);
}

static void assert_key_lock(void)
{
        WARN_ON(!mutex_is_locked(&key_mutex));
}

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

        return NULL;
}

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

        assert_key_lock();
        might_sleep();

        if (!key->local->ops->set_key)
                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, SET_KEY, sdata, sta, &key->conf);

        if (!ret) {
                spin_lock_bh(&todo_lock);
                key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
                spin_unlock_bh(&todo_lock);
        }

        if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
                printk(KERN_ERR "mac80211-%s: failed to set key "
                       "(%d, %pM) to hardware (%d)\n",
                       wiphy_name(key->local->hw.wiphy),
                       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
}

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

        assert_key_lock();
        might_sleep();

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

        spin_lock_bh(&todo_lock);
        if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
                spin_unlock_bh(&todo_lock);
                return;
        }
        spin_unlock_bh(&todo_lock);

        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)
                printk(KERN_ERR "mac80211-%s: failed to remove key "
                       "(%d, %pM) from hardware (%d)\n",
                       wiphy_name(key->local->hw.wiphy),
                       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);

        spin_lock_bh(&todo_lock);
        key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
        spin_unlock_bh(&todo_lock);
}

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

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

        rcu_assign_pointer(sdata->default_key, key);

        if (key)
                add_todo(key, KEY_FLAG_TODO_DEFKEY);
}

void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
{
        unsigned long flags;

        spin_lock_irqsave(&sdata->local->key_lock, flags);
        __ieee80211_set_default_key(sdata, idx);
        spin_unlock_irqrestore(&sdata->local->key_lock, flags);
}

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

        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);

        if (key)
                add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
}

void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
                                    int idx)
{
        unsigned long flags;

        spin_lock_irqsave(&sdata->local->key_lock, flags);
        __ieee80211_set_default_mgmt_key(sdata, idx);
        spin_unlock_irqrestore(&sdata->local->key_lock, flags);
}


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

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

        if (sta) {
                rcu_assign_pointer(sta->key, new);
        } else {
                WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);

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

                defkey = old && sdata->default_key == old;
                defmgmtkey = old && sdata->default_mgmt_key == old;

                if (defkey && !new)
                        __ieee80211_set_default_key(sdata, -1);
                if (defmgmtkey && !new)
                        __ieee80211_set_default_mgmt_key(sdata, -1);

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

        if (old) {
                /*
                 * We'll use an empty list to indicate that the key
                 * has already been removed.
                 */
                list_del_init(&old->list);
        }
}

struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
                                          int idx,
                                          size_t key_len,
                                          const u8 *key_data,
                                          size_t seq_len, const u8 *seq)
{
        struct ieee80211_key *key;
        int i, j;

        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 NULL;

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

        key->conf.alg = alg;
        key->conf.keyidx = idx;
        key->conf.keylen = key_len;
        switch (alg) {
        case ALG_WEP:
                key->conf.iv_len = WEP_IV_LEN;
                key->conf.icv_len = WEP_ICV_LEN;
                break;
        case ALG_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 ALG_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; i++)
                                for (j = 0; j < CCMP_PN_LEN; j++)
                                        key->u.ccmp.rx_pn[i][j] =
                                                seq[CCMP_PN_LEN - j - 1];
                }
                break;
        case ALG_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];
                break;
        }
        memcpy(key->conf.key, key_data, key_len);
        INIT_LIST_HEAD(&key->list);
        INIT_LIST_HEAD(&key->todo);

        if (alg == ALG_CCMP) {
                /*
                 * 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 (!key->u.ccmp.tfm) {
                        kfree(key);
                        return NULL;
                }
        }

        if (alg == ALG_AES_CMAC) {
                /*
                 * 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 (!key->u.aes_cmac.tfm) {
                        kfree(key);
                        return NULL;
                }
        }

        return key;
}

void ieee80211_key_link(struct ieee80211_key *key,
                        struct ieee80211_sub_if_data *sdata,
                        struct sta_info *sta)
{
        struct ieee80211_key *old_key;
        unsigned long flags;
        int idx;

        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;

                /*
                 * This key is for a specific sta interface,
                 * inform the driver that it should try to store
                 * this key as pairwise key.
                 */
                key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
        } else {
                if (sdata->vif.type == NL80211_IFTYPE_STATION) {
                        struct sta_info *ap;

                        /*
                         * We're getting a sta pointer in,
                         * so must be under RCU read lock.
                         */

                        /* 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;
                        }
                }
        }

        spin_lock_irqsave(&sdata->local->key_lock, flags);

        if (sta)
                old_key = sta->key;
        else
                old_key = sdata->keys[idx];

        __ieee80211_key_replace(sdata, sta, old_key, key);

        /* free old key later */
        add_todo(old_key, KEY_FLAG_TODO_DELETE);

        add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
        if (ieee80211_sdata_running(sdata))
                add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);

        spin_unlock_irqrestore(&sdata->local->key_lock, flags);
}

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, NULL);

        add_todo(key, KEY_FLAG_TODO_DELETE);
}

void ieee80211_key_free(struct ieee80211_key *key)
{
        unsigned long flags;

        if (!key)
                return;

        if (!key->sdata) {
                /* The key has not been linked yet, simply free it
                 * and don't Oops */
                if (key->conf.alg == ALG_CCMP)
                        ieee80211_aes_key_free(key->u.ccmp.tfm);
                kfree(key);
                return;
        }

        spin_lock_irqsave(&key->sdata->local->key_lock, flags);
        __ieee80211_key_free(key);
        spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
}

/*
 * To be safe against concurrent manipulations of the list (which shouldn't
 * actually happen) we need to hold the spinlock. But under the spinlock we
 * can't actually do much, so we defer processing to the todo list. Then run
 * the todo list to be sure the operation and possibly previously pending
 * operations are completed.
 */
static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
                                        u32 todo_flags)
{
        struct ieee80211_key *key;
        unsigned long flags;

        might_sleep();

        spin_lock_irqsave(&sdata->local->key_lock, flags);
        list_for_each_entry(key, &sdata->key_list, list)
                add_todo(key, todo_flags);
        spin_unlock_irqrestore(&sdata->local->key_lock, flags);

        ieee80211_key_todo();
}

void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
{
        ASSERT_RTNL();

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

        ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
}

void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
{
        ASSERT_RTNL();

        ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
}

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

        ieee80211_key_disable_hw_accel(key);

        if (key->conf.alg == ALG_CCMP)
                ieee80211_aes_key_free(key->u.ccmp.tfm);
        if (key->conf.alg == ALG_AES_CMAC)
                ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
        ieee80211_debugfs_key_remove(key);

        kfree(key);
}

static void __ieee80211_key_todo(void)
{
        struct ieee80211_key *key;
        bool work_done;
        u32 todoflags;

        /*
         * NB: sta_info_destroy relies on this!
         */
        synchronize_rcu();

        spin_lock_bh(&todo_lock);
        while (!list_empty(&todo_list)) {
                key = list_first_entry(&todo_list, struct ieee80211_key, todo);
                list_del_init(&key->todo);
                todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
                                          KEY_FLAG_TODO_DEFKEY |
                                          KEY_FLAG_TODO_DEFMGMTKEY |
                                          KEY_FLAG_TODO_HWACCEL_ADD |
                                          KEY_FLAG_TODO_HWACCEL_REMOVE |
                                          KEY_FLAG_TODO_DELETE);
                key->flags &= ~todoflags;
                spin_unlock_bh(&todo_lock);

                work_done = false;

                if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
                        ieee80211_debugfs_key_add(key);
                        work_done = true;
                }
                if (todoflags & KEY_FLAG_TODO_DEFKEY) {
                        ieee80211_debugfs_key_remove_default(key->sdata);
                        ieee80211_debugfs_key_add_default(key->sdata);
                        work_done = true;
                }
                if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
                        ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
                        ieee80211_debugfs_key_add_mgmt_default(key->sdata);
                        work_done = true;
                }
                if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
                        ieee80211_key_enable_hw_accel(key);
                        work_done = true;
                }
                if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
                        ieee80211_key_disable_hw_accel(key);
                        work_done = true;
                }
                if (todoflags & KEY_FLAG_TODO_DELETE) {
                        __ieee80211_key_destroy(key);
                        work_done = true;
                }

                WARN_ON(!work_done);

                spin_lock_bh(&todo_lock);
        }
        spin_unlock_bh(&todo_lock);
}

void ieee80211_key_todo(void)
{
        ieee80211_key_lock();
        __ieee80211_key_todo();
        ieee80211_key_unlock();
}

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

        ieee80211_key_lock();

        ieee80211_debugfs_key_remove_default(sdata);
        ieee80211_debugfs_key_remove_mgmt_default(sdata);

        spin_lock_irqsave(&sdata->local->key_lock, flags);
        list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
                __ieee80211_key_free(key);
        spin_unlock_irqrestore(&sdata->local->key_lock, flags);

        __ieee80211_key_todo();

        ieee80211_key_unlock();
}