rt2x00crypto.c

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/*
    Copyright (C) 2004 - 2009 Ivo van Doorn <[email protected]>
    <http://rt2x00.serialmonkey.com>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the
    Free Software Foundation, Inc.,
    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*
    Module: rt2x00lib
    Abstract: rt2x00 crypto specific routines.
 */

#include <linux/kernel.h>
#include <linux/module.h>

#include "rt2x00.h"
#include "rt2x00lib.h"

enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
{
    switch (key->cipher) {
    case WLAN_CIPHER_SUITE_WEP40:
        return CIPHER_WEP64;
    case WLAN_CIPHER_SUITE_WEP104:
        return CIPHER_WEP128;
    case WLAN_CIPHER_SUITE_TKIP:
        return CIPHER_TKIP;
    case WLAN_CIPHER_SUITE_CCMP:
        return CIPHER_AES;
    default:
        return CIPHER_NONE;
    }
}

void rt2x00crypto_create_tx_descriptor(struct rt2x00_dev *rt2x00dev,
                       struct sk_buff *skb,
                       struct txentry_desc *txdesc)
{
    struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
    struct ieee80211_key_conf *hw_key = tx_info->control.hw_key;

    if (!test_bit(CAPABILITY_HW_CRYPTO, &rt2x00dev->cap_flags) || !hw_key)
        return;

    __set_bit(ENTRY_TXD_ENCRYPT, &txdesc->flags);

    txdesc->cipher = rt2x00crypto_key_to_cipher(hw_key);

    if (hw_key->flags & IEEE80211_KEY_FLAG_PAIRWISE)
        __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);

    txdesc->key_idx = hw_key->hw_key_idx;
    txdesc->iv_offset = txdesc->header_length;
    txdesc->iv_len = hw_key->iv_len;

    if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
        __set_bit(ENTRY_TXD_ENCRYPT_IV, &txdesc->flags);

    if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC))
        __set_bit(ENTRY_TXD_ENCRYPT_MMIC, &txdesc->flags);
}

unsigned int rt2x00crypto_tx_overhead(struct rt2x00_dev *rt2x00dev,
                      struct sk_buff *skb)
{
    struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
    struct ieee80211_key_conf *key = tx_info->control.hw_key;
    unsigned int overhead = 0;

    if (!test_bit(CAPABILITY_HW_CRYPTO, &rt2x00dev->cap_flags) || !key)
        return overhead;

    /*
     * Extend frame length to include IV/EIV/ICV/MMIC,
     * note that these lengths should only be added when
     * mac80211 does not generate it.
     */
    overhead += key->icv_len;

    if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
        overhead += key->iv_len;

    if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
        if (key->cipher == WLAN_CIPHER_SUITE_TKIP)
            overhead += 8;
    }

    return overhead;
}

void rt2x00crypto_tx_copy_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
{
    struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);

    if (unlikely(!txdesc->iv_len))
        return;

    /* Copy IV/EIV data */
    memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);
}

void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
{
    struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);

    if (unlikely(!txdesc->iv_len))
        return;

    /* Copy IV/EIV data */
    memcpy(skbdesc->iv, skb->data + txdesc->iv_offset, txdesc->iv_len);

    /* Move ieee80211 header */
    memmove(skb->data + txdesc->iv_len, skb->data, txdesc->iv_offset);

    /* Pull buffer to correct size */
    skb_pull(skb, txdesc->iv_len);
    txdesc->length -= txdesc->iv_len;

    /* IV/EIV data has officially been stripped */
    skbdesc->flags |= SKBDESC_IV_STRIPPED;
}

void rt2x00crypto_tx_insert_iv(struct sk_buff *skb, unsigned int header_length)
{
    struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
    const unsigned int iv_len =
        ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);

    if (!(skbdesc->flags & SKBDESC_IV_STRIPPED))
        return;

    skb_push(skb, iv_len);

    /* Move ieee80211 header */
    memmove(skb->data, skb->data + iv_len, header_length);

    /* Copy IV/EIV data */
    memcpy(skb->data + header_length, skbdesc->iv, iv_len);

    /* IV/EIV data has returned into the frame */
    skbdesc->flags &= ~SKBDESC_IV_STRIPPED;
}

void rt2x00crypto_rx_insert_iv(struct sk_buff *skb,
                   unsigned int header_length,
                   struct rxdone_entry_desc *rxdesc)
{
    unsigned int payload_len = rxdesc->size - header_length;
    unsigned int align = ALIGN_SIZE(skb, header_length);
    unsigned int iv_len;
    unsigned int icv_len;
    unsigned int transfer = 0;

    /*
     * WEP64/WEP128: Provides IV & ICV
     * TKIP: Provides IV/EIV & ICV
     * AES: Provies IV/EIV & ICV
     */
    switch (rxdesc->cipher) {
    case CIPHER_WEP64:
    case CIPHER_WEP128:
        iv_len = 4;
        icv_len = 4;
        break;
    case CIPHER_TKIP:
        iv_len = 8;
        icv_len = 4;
        break;
    case CIPHER_AES:
        iv_len = 8;
        icv_len = 8;
        break;
    default:
        /* Unsupport type */
        return;
    }

    /*
     * Make room for new data. There are 2 possibilities
     * either the alignment is already present between
     * the 802.11 header and payload. In that case we
     * we have to move the header less then the iv_len
     * since we can use the already available l2pad bytes
     * for the iv data.
     * When the alignment must be added manually we must
     * move the header more then iv_len since we must
     * make room for the payload move as well.
     */
    if (rxdesc->dev_flags & RXDONE_L2PAD) {
        skb_push(skb, iv_len - align);
        skb_put(skb, icv_len);

        /* Move ieee80211 header */
        memmove(skb->data + transfer,
            skb->data + transfer + (iv_len - align),
            header_length);
        transfer += header_length;
    } else {
        skb_push(skb, iv_len + align);
        if (align < icv_len)
            skb_put(skb, icv_len - align);
        else if (align > icv_len)
            skb_trim(skb, rxdesc->size + iv_len + icv_len);

        /* Move ieee80211 header */
        memmove(skb->data + transfer,
            skb->data + transfer + iv_len + align,
            header_length);
        transfer += header_length;
    }

    /* Copy IV/EIV data */
    memcpy(skb->data + transfer, rxdesc->iv, iv_len);
    transfer += iv_len;

    /*
     * Move payload for alignment purposes. Note that
     * this is only needed when no l2 padding is present.
     */
    if (!(rxdesc->dev_flags & RXDONE_L2PAD)) {
        memmove(skb->data + transfer,
            skb->data + transfer + align,
            payload_len);
    }

    /*
     * NOTE: Always count the payload as transferred,
     * even when alignment was set to zero. This is required
     * for determining the correct offset for the ICV data.
     */
    transfer += payload_len;

    /*
     * Copy ICV data
     * AES appends 8 bytes, we can't fill the upper
     * 4 bytes, but mac80211 doesn't care about what
     * we provide here anyway and strips it immediately.
     */
    memcpy(skb->data + transfer, &rxdesc->icv, 4);
    transfer += icv_len;

    /* IV/EIV/ICV has been inserted into frame */
    rxdesc->size = transfer;
    rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
}