drivers/net/wireless/rt2x00/rt2x00crypto.c

   1 /*
   2         Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
   3         <http://rt2x00.serialmonkey.com>
   4
   5         This program is free software; you can redistribute it and/or modify
   6         it under the terms of the GNU General Public License as published by
   7         the Free Software Foundation; either version 2 of the License, or
   8         (at your option) any later version.
   9
  10         This program is distributed in the hope that it will be useful,
  11         but WITHOUT ANY WARRANTY; without even the implied warranty of
  12         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13         GNU General Public License for more details.
  14
  15         You should have received a copy of the GNU General Public License
  16         along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 /*
  20         Module: rt2x00lib
  21         Abstract: rt2x00 crypto specific routines.
  22  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26
  27 #include "rt2x00.h"
  28 #include "rt2x00lib.h"
  29
  30 enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
  31 {
  32         switch (key->cipher) {
  33         case WLAN_CIPHER_SUITE_WEP40:
  34                 return CIPHER_WEP64;
  35         case WLAN_CIPHER_SUITE_WEP104:
  36                 return CIPHER_WEP128;
  37         case WLAN_CIPHER_SUITE_TKIP:
  38                 return CIPHER_TKIP;
  39         case WLAN_CIPHER_SUITE_CCMP:
  40                 return CIPHER_AES;
  41         default:
  42                 return CIPHER_NONE;
  43         }
  44 }
  45
  46 void rt2x00crypto_create_tx_descriptor(struct rt2x00_dev *rt2x00dev,
  47                                        struct sk_buff *skb,
  48                                        struct txentry_desc *txdesc)
  49 {
  50         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
  51         struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
  52
  53         if (!rt2x00_has_cap_hw_crypto(rt2x00dev) || !hw_key)
  54                 return;
  55
  56         __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);
  57
  58         txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);
  59
  60         if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
  61                 __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);
  62
  63         txdesc->key_idx = hw_key->hw_key_idx;
  64         txdesc->iv_offset = txdesc->header_length;
  65         txdesc->iv_len = hw_key->iv_len;
  66
  67         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  68                 __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);
  69
  70         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
  71                 __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
  72 }
  73
  74 unsigned int rt2x00crypto_tx_overhead(struct rt2x00_dev *rt2x00dev,
  75                                       struct sk_buff *skb)
  76 {
  77         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
  78         struct ieee80211_key_conf *key = tx_info->control.hw_key;
  79         unsigned int overhead = 0;
  80
  81         if (!rt2x00_has_cap_hw_crypto(rt2x00dev) || !key)
  82                 return overhead;
  83
  84         /*
  85          * Extend frame length to include IV/EIV/ICV/MMIC,
  86          * note that these lengths should only be added when
  87          * mac80211 does not generate it.
  88          */
  89         overhead += key->icv_len;
  90
  91         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  92                 overhead += key->iv_len;
  93
  94         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
  95                 if (key->cipher == WLAN_CIPHER_SUITE_TKIP)
  96                         overhead += 8;
  97         }
  98
  99         return overhead;
 100 }
 101
 102 void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
 103 {
 104         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 105
 106         if (unlikely(!txdesc->iv_len))
 107                 return;
 108
 109         /* Copy IV/EIV data */
 110         memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
 111 }
 112
 113 void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
 114 {
 115         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 116
 117         if (unlikely(!txdesc->iv_len))
 118                 return;
 119
 120         /* Copy IV/EIV data */
 121         memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
 122
 123         /* Move ieee80211 header */
 124         memmove(skb->data + txdesc->iv_len, skb->data, txdesc->iv_offset);
 125
 126         /* Pull buffer to correct size */
 127         skb_pull(skb, txdesc->iv_len);
 128         txdesc->length -= txdesc->iv_len;
 129
 130         /* IV/EIV data has officially been stripped */
 131         skbdesc->flags |= SKBDESC_IV_STRIPPED;
 132 }
 133
 134 void rt2x00crypto_tx_insert_iv(struct sk_buff *skb, unsigned int header_length)
 135 {
 136         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 137         const unsigned int iv_len =
 138             ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);
 139
 140         if (!(skbdesc->flags & SKBDESC_IV_STRIPPED))
 141                 return;
 142
 143         skb_push(skb, iv_len);
 144
 145         /* Move ieee80211 header */
 146         memmove(skb->data, skb->data + iv_len, header_length);
 147
 148         /* Copy IV/EIV data */
 149         memcpy(skb->data + header_length, skbdesc->iv, iv_len);
 150
 151         /* IV/EIV data has returned into the frame */
 152         skbdesc->flags &= ~SKBDESC_IV_STRIPPED;
 153 }
 154
 155 void rt2x00crypto_rx_insert_iv(struct sk_buff *skb,
 156                                unsigned int header_length,
 157                                struct rxdone_entry_desc *rxdesc)
 158 {
 159         unsigned int payload_len = rxdesc->size - header_length;
 160         unsigned int align = ALIGN_SIZE(skb, header_length);
 161         unsigned int iv_len;
 162         unsigned int icv_len;
 163         unsigned int transfer = 0;
 164
 165         /*
 166          * WEP64/WEP128: Provides IV & ICV
 167          * TKIP: Provides IV/EIV & ICV
 168          * AES: Provies IV/EIV & ICV
 169          */
 170         switch (rxdesc->cipher) {
 171         case CIPHER_WEP64:
 172         case CIPHER_WEP128:
 173                 iv_len = 4;
 174                 icv_len = 4;
 175                 break;
 176         case CIPHER_TKIP:
 177                 iv_len = 8;
 178                 icv_len = 4;
 179                 break;
 180         case CIPHER_AES:
 181                 iv_len = 8;
 182                 icv_len = 8;
 183                 break;
 184         default:
 185                 /* Unsupport type */
 186                 return;
 187         }
 188
 189         /*
 190          * Make room for new data. There are 2 possibilities
 191          * either the alignment is already present between
 192          * the 802.11 header and payload. In that case we
 193          * we have to move the header less then the iv_len
 194          * since we can use the already available l2pad bytes
 195          * for the iv data.
 196          * When the alignment must be added manually we must
 197          * move the header more then iv_len since we must
 198          * make room for the payload move as well.
 199          */
 200         if (rxdesc->dev_flags & RXDONE_L2PAD) {
 201                 skb_push(skb, iv_len - align);
 202                 skb_put(skb, icv_len);
 203
 204                 /* Move ieee80211 header */
 205                 memmove(skb->data + transfer,
 206                         skb->data + transfer + (iv_len - align),
 207                         header_length);
 208                 transfer += header_length;
 209         } else {
 210                 skb_push(skb, iv_len + align);
 211                 if (align < icv_len)
 212                         skb_put(skb, icv_len - align);
 213                 else if (align > icv_len)
 214                         skb_trim(skb, rxdesc->size + iv_len + icv_len);
 215
 216                 /* Move ieee80211 header */
 217                 memmove(skb->data + transfer,
 218                         skb->data + transfer + iv_len + align,
 219                         header_length);
 220                 transfer += header_length;
 221         }
 222
 223         /* Copy IV/EIV data */
 224         memcpy(skb->data + transfer, rxdesc->iv, iv_len);
 225         transfer += iv_len;
 226
 227         /*
 228          * Move payload for alignment purposes. Note that
 229          * this is only needed when no l2 padding is present.
 230          */
 231         if (!(rxdesc->dev_flags & RXDONE_L2PAD)) {
 232                 memmove(skb->data + transfer,
 233                         skb->data + transfer + align,
 234                         payload_len);
 235         }
 236
 237         /*
 238          * NOTE: Always count the payload as transferred,
 239          * even when alignment was set to zero. This is required
 240          * for determining the correct offset for the ICV data.
 241          */
 242         transfer += payload_len;
 243
 244         /*
 245          * Copy ICV data
 246          * AES appends 8 bytes, we can't fill the upper
 247          * 4 bytes, but mac80211 doesn't care about what
 248          * we provide here anyway and strips it immediately.
 249          */
 250         memcpy(skb->data + transfer, &rxdesc->icv, 4);
 251         transfer += icv_len;
 252
 253         /* IV/EIV/ICV has been inserted into frame */
 254         rxdesc->size = transfer;
 255         rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
 256 }