drivers/net/wireless/rt2x00/rt2x00crypto.c

   1 /*
   2         Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
   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, write to the
  17         Free Software Foundation, Inc.,
  18         59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 /*
  22         Module: rt2x00lib
  23         Abstract: rt2x00 crypto specific routines.
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28
  29 #include "rt2x00.h"
  30 #include "rt2x00lib.h"
  31
  32 enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
  33 {
  34         switch (key->alg) {
  35         case ALG_WEP:
  36                 if (key->keylen == WLAN_KEY_LEN_WEP40)
  37                         return CIPHER_WEP64;
  38                 else
  39                         return CIPHER_WEP128;
  40         case ALG_TKIP:
  41                 return CIPHER_TKIP;
  42         case ALG_CCMP:
  43                 return CIPHER_AES;
  44         default:
  45                 return CIPHER_NONE;
  46         }
  47 }
  48
  49 void rt2x00crypto_create_tx_descriptor(struct queue_entry *entry,
  50                                        struct txentry_desc *txdesc)
  51 {
  52         struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
  53         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(entry->skb);
  54         struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;
  55
  56         if (!test_bit(CONFIG_SUPPORT_HW_CRYPTO, &rt2x00dev->flags) || !hw_key)
  57                 return;
  58
  59         __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);
  60
  61         txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);
  62
  63         if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
  64                 __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);
  65
  66         txdesc->key_idx = hw_key->hw_key_idx;
  67         txdesc->iv_offset = txdesc->header_length;
  68         txdesc->iv_len = hw_key->iv_len;
  69
  70         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  71                 __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);
  72
  73         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
  74                 __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
  75 }
  76
  77 unsigned int rt2x00crypto_tx_overhead(struct rt2x00_dev *rt2x00dev,
  78                                       struct sk_buff *skb)
  79 {
  80         struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
  81         struct ieee80211_key_conf *key = tx_info->control.hw_key;
  82         unsigned int overhead = 0;
  83
  84         if (!test_bit(CONFIG_SUPPORT_HW_CRYPTO, &rt2x00dev->flags) || !key)
  85                 return overhead;
  86
  87         /*
  88          * Extend frame length to include IV/EIV/ICV/MMIC,
  89          * note that these lengths should only be added when
  90          * mac80211 does not generate it.
  91          */
  92         overhead += key->icv_len;
  93
  94         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
  95                 overhead += key->iv_len;
  96
  97         if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
  98                 if (key->alg == ALG_TKIP)
  99                         overhead += 8;
 100         }
 101
 102         return overhead;
 103 }
 104
 105 void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
 106 {
 107         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 108
 109         if (unlikely(!txdesc->iv_len))
 110                 return;
 111
 112         /* Copy IV/EIV data */
 113         memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
 114 }
 115
 116 void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
 117 {
 118         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 119
 120         if (unlikely(!txdesc->iv_len))
 121                 return;
 122
 123         /* Copy IV/EIV data */
 124         memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
 125
 126         /* Move ieee80211 header */
 127         memmove(skb->data + txdesc->iv_len, skb->data, txdesc->iv_offset);
 128
 129         /* Pull buffer to correct size */
 130         skb_pull(skb, txdesc->iv_len);
 131
 132         /* IV/EIV data has officially been stripped */
 133         skbdesc->flags |= SKBDESC_IV_STRIPPED;
 134 }
 135
 136 void rt2x00crypto_tx_insert_iv(struct sk_buff *skb, unsigned int header_length)
 137 {
 138         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
 139         const unsigned int iv_len =
 140             ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);
 141
 142         if (!(skbdesc->flags & SKBDESC_IV_STRIPPED))
 143                 return;
 144
 145         skb_push(skb, iv_len);
 146
 147         /* Move ieee80211 header */
 148         memmove(skb->data, skb->data + iv_len, header_length);
 149
 150         /* Copy IV/EIV data */
 151         memcpy(skb->data + header_length, skbdesc->iv, iv_len);
 152
 153         /* IV/EIV data has returned into the frame */
 154         skbdesc->flags &= ~SKBDESC_IV_STRIPPED;
 155 }
 156
 157 void rt2x00crypto_rx_insert_iv(struct sk_buff *skb,
 158                                unsigned int header_length,
 159                                struct rxdone_entry_desc *rxdesc)
 160 {
 161         unsigned int payload_len = rxdesc->size - header_length;
 162         unsigned int align = ALIGN_SIZE(skb, header_length);
 163         unsigned int iv_len;
 164         unsigned int icv_len;
 165         unsigned int transfer = 0;
 166
 167         /*
 168          * WEP64/WEP128: Provides IV & ICV
 169          * TKIP: Provides IV/EIV & ICV
 170          * AES: Provies IV/EIV & ICV
 171          */
 172         switch (rxdesc->cipher) {
 173         case CIPHER_WEP64:
 174         case CIPHER_WEP128:
 175                 iv_len = 4;
 176                 icv_len = 4;
 177                 break;
 178         case CIPHER_TKIP:
 179                 iv_len = 8;
 180                 icv_len = 4;
 181                 break;
 182         case CIPHER_AES:
 183                 iv_len = 8;
 184                 icv_len = 8;
 185                 break;
 186         default:
 187                 /* Unsupport type */
 188                 return;
 189         }
 190
 191         /*
 192          * Make room for new data. There are 2 possibilities
 193          * either the alignment is already present between
 194          * the 802.11 header and payload. In that case we
 195          * we have to move the header less then the iv_len
 196          * since we can use the already available l2pad bytes
 197          * for the iv data.
 198          * When the alignment must be added manually we must
 199          * move the header more then iv_len since we must
 200          * make room for the payload move as well.
 201          */
 202         if (rxdesc->dev_flags & RXDONE_L2PAD) {
 203                 skb_push(skb, iv_len - align);
 204                 skb_put(skb, icv_len);
 205
 206                 /* Move ieee80211 header */
 207                 memmove(skb->data + transfer,
 208                         skb->data + transfer + (iv_len - align),
 209                         header_length);
 210                 transfer += header_length;
 211         } else {
 212                 skb_push(skb, iv_len + align);
 213                 if (align < icv_len)
 214                         skb_put(skb, icv_len - align);
 215                 else if (align > icv_len)
 216                         skb_trim(skb, rxdesc->size + iv_len + icv_len);
 217
 218                 /* Move ieee80211 header */
 219                 memmove(skb->data + transfer,
 220                         skb->data + transfer + iv_len + align,
 221                         header_length);
 222                 transfer += header_length;
 223         }
 224
 225         /* Copy IV/EIV data */
 226         memcpy(skb->data + transfer, rxdesc->iv, iv_len);
 227         transfer += iv_len;
 228
 229         /*
 230          * Move payload for alignment purposes. Note that
 231          * this is only needed when no l2 padding is present.
 232          */
 233         if (!(rxdesc->dev_flags & RXDONE_L2PAD)) {
 234                 memmove(skb->data + transfer,
 235                         skb->data + transfer + align,
 236                         payload_len);
 237         }
 238
 239         /*
 240          * NOTE: Always count the payload as transfered,
 241          * even when alignment was set to zero. This is required
 242          * for determining the correct offset for the ICV data.
 243          */
 244         transfer += payload_len;
 245
 246         /*
 247          * Copy ICV data
 248          * AES appends 8 bytes, we can't fill the upper
 249          * 4 bytes, but mac80211 doesn't care about what
 250          * we provide here anyway and strips it immediately.
 251          */
 252         memcpy(skb->data + transfer, &rxdesc->icv, 4);
 253         transfer += icv_len;
 254
 255         /* IV/EIV/ICV has been inserted into frame */
 256         rxdesc->size = transfer;
 257         rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
 258 }