net/mac80211/key.c

   1 /*
   2  * Copyright 2002-2005, Instant802 Networks, Inc.
   3  * Copyright 2005-2006, Devicescape Software, Inc.
   4  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
   5  * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/if_ether.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/list.h>
  15 #include <linux/rcupdate.h>
  16 #include <net/mac80211.h>
  17 #include "ieee80211_i.h"
  18 #include "debugfs_key.h"
  19 #include "aes_ccm.h"
  20
  21
  22 /*
  23  * Key handling basics
  24  *
  25  * Key handling in mac80211 is done based on per-interface (sub_if_data)
  26  * keys and per-station keys. Since each station belongs to an interface,
  27  * each station key also belongs to that interface.
  28  *
  29  * Hardware acceleration is done on a best-effort basis, for each key
  30  * that is eligible the hardware is asked to enable that key but if
  31  * it cannot do that they key is simply kept for software encryption.
  32  * There is currently no way of knowing this except by looking into
  33  * debugfs.
  34  *
  35  * All operations here are called under RTNL so no extra locking is
  36  * required.
  37  */
  38
  39 static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
  40 static const u8 zero_addr[ETH_ALEN];
  41
  42 static const u8 *get_mac_for_key(struct ieee80211_key *key)
  43 {
  44         const u8 *addr = bcast_addr;
  45
  46         /*
  47          * If we're an AP we won't ever receive frames with a non-WEP
  48          * group key so we tell the driver that by using the zero MAC
  49          * address to indicate a transmit-only key.
  50          */
  51         if (key->conf.alg != ALG_WEP &&
  52             (key->sdata->type == IEEE80211_IF_TYPE_AP ||
  53              key->sdata->type == IEEE80211_IF_TYPE_VLAN))
  54                 addr = zero_addr;
  55
  56         if (key->sta)
  57                 addr = key->sta->addr;
  58
  59         return addr;
  60 }
  61
  62 static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
  63 {
  64         const u8 *addr;
  65         int ret;
  66
  67         if (!key->local->ops->set_key)
  68                 return;
  69
  70         addr = get_mac_for_key(key);
  71
  72         ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
  73                                        key->sdata->dev->dev_addr, addr,
  74                                        &key->conf);
  75
  76         if (!ret)
  77                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
  78
  79         if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
  80                 printk(KERN_ERR "mac80211-%s: failed to set key "
  81                        "(%d, " MAC_FMT ") to hardware (%d)\n",
  82                        wiphy_name(key->local->hw.wiphy),
  83                        key->conf.keyidx, MAC_ARG(addr), ret);
  84 }
  85
  86 static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
  87 {
  88         const u8 *addr;
  89         int ret;
  90
  91         if (!key->local->ops->set_key)
  92                 return;
  93
  94         if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
  95                 return;
  96
  97         addr = get_mac_for_key(key);
  98
  99         ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
 100                                        key->sdata->dev->dev_addr, addr,
 101                                        &key->conf);
 102
 103         if (ret)
 104                 printk(KERN_ERR "mac80211-%s: failed to remove key "
 105                        "(%d, " MAC_FMT ") from hardware (%d)\n",
 106                        wiphy_name(key->local->hw.wiphy),
 107                        key->conf.keyidx, MAC_ARG(addr), ret);
 108
 109         key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 110 }
 111
 112 struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
 113                                           struct sta_info *sta,
 114                                           ieee80211_key_alg alg,
 115                                           int idx,
 116                                           size_t key_len,
 117                                           const u8 *key_data)
 118 {
 119         struct ieee80211_key *key;
 120
 121         BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS);
 122         BUG_ON(alg == ALG_NONE);
 123
 124         key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
 125         if (!key)
 126                 return NULL;
 127
 128         /*
 129          * Default to software encryption; we'll later upload the
 130          * key to the hardware if possible.
 131          */
 132         key->conf.flags = 0;
 133         key->flags = 0;
 134
 135         key->conf.alg = alg;
 136         key->conf.keyidx = idx;
 137         key->conf.keylen = key_len;
 138         memcpy(key->conf.key, key_data, key_len);
 139
 140         key->local = sdata->local;
 141         key->sdata = sdata;
 142         key->sta = sta;
 143
 144         if (alg == ALG_CCMP) {
 145                 /*
 146                  * Initialize AES key state here as an optimization so that
 147                  * it does not need to be initialized for every packet.
 148                  */
 149                 key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
 150                 if (!key->u.ccmp.tfm) {
 151                         ieee80211_key_free(key);
 152                         return NULL;
 153                 }
 154         }
 155
 156         ieee80211_debugfs_key_add(key->local, key);
 157
 158         /* remove key first */
 159         if (sta)
 160                 ieee80211_key_free(sta->key);
 161         else
 162                 ieee80211_key_free(sdata->keys[idx]);
 163
 164         if (sta) {
 165                 ieee80211_debugfs_key_sta_link(key, sta);
 166
 167                 /*
 168                  * some hardware cannot handle TKIP with QoS, so
 169                  * we indicate whether QoS could be in use.
 170                  */
 171                 if (sta->flags & WLAN_STA_WME)
 172                         key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;
 173         } else {
 174                 if (sdata->type == IEEE80211_IF_TYPE_STA) {
 175                         struct sta_info *ap;
 176
 177                         /* same here, the AP could be using QoS */
 178                         ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
 179                         if (ap) {
 180                                 if (ap->flags & WLAN_STA_WME)
 181                                         key->conf.flags |=
 182                                                 IEEE80211_KEY_FLAG_WMM_STA;
 183                                 sta_info_put(ap);
 184                         }
 185                 }
 186         }
 187
 188         /* enable hwaccel if appropriate */
 189         if (netif_running(key->sdata->dev))
 190                 ieee80211_key_enable_hw_accel(key);
 191
 192         if (sta)
 193                 rcu_assign_pointer(sta->key, key);
 194         else
 195                 rcu_assign_pointer(sdata->keys[idx], key);
 196
 197         list_add(&key->list, &sdata->key_list);
 198
 199         return key;
 200 }
 201
 202 void ieee80211_key_free(struct ieee80211_key *key)
 203 {
 204         if (!key)
 205                 return;
 206
 207         if (key->sta) {
 208                 rcu_assign_pointer(key->sta->key, NULL);
 209         } else {
 210                 if (key->sdata->default_key == key)
 211                         ieee80211_set_default_key(key->sdata, -1);
 212                 if (key->conf.keyidx >= 0 &&
 213                     key->conf.keyidx < NUM_DEFAULT_KEYS)
 214                         rcu_assign_pointer(key->sdata->keys[key->conf.keyidx],
 215                                            NULL);
 216                 else
 217                         WARN_ON(1);
 218         }
 219
 220         /* wait for all key users to complete */
 221         synchronize_rcu();
 222
 223         /* remove from hwaccel if appropriate */
 224         ieee80211_key_disable_hw_accel(key);
 225
 226         if (key->conf.alg == ALG_CCMP)
 227                 ieee80211_aes_key_free(key->u.ccmp.tfm);
 228         ieee80211_debugfs_key_remove(key);
 229
 230         list_del(&key->list);
 231
 232         kfree(key);
 233 }
 234
 235 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
 236 {
 237         struct ieee80211_key *key = NULL;
 238
 239         if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
 240                 key = sdata->keys[idx];
 241
 242         if (sdata->default_key != key) {
 243                 ieee80211_debugfs_key_remove_default(sdata);
 244
 245                 rcu_assign_pointer(sdata->default_key, key);
 246
 247                 if (sdata->default_key)
 248                         ieee80211_debugfs_key_add_default(sdata);
 249         }
 250 }
 251
 252 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
 253 {
 254         struct ieee80211_key *key, *tmp;
 255
 256         list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
 257                 ieee80211_key_free(key);
 258 }
 259
 260 void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
 261 {
 262         struct ieee80211_key *key;
 263
 264         WARN_ON(!netif_running(sdata->dev));
 265         if (!netif_running(sdata->dev))
 266                 return;
 267
 268         list_for_each_entry(key, &sdata->key_list, list)
 269                 ieee80211_key_enable_hw_accel(key);
 270 }
 271
 272 void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
 273 {
 274         struct ieee80211_key *key;
 275
 276         list_for_each_entry(key, &sdata->key_list, list)
 277                 ieee80211_key_disable_hw_accel(key);
 278 }