mic.c

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/* Orinoco MIC helpers
 *
 * See copyright notice in main.c
 */
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/if_ether.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>

#include "orinoco.h"
#include "mic.h"

/********************************************************************/
/* Michael MIC crypto setup                                         */
/********************************************************************/
int orinoco_mic_init(struct orinoco_private *priv)
{
    priv->tx_tfm_mic = crypto_alloc_hash("michael_mic", 0, 0);
    if (IS_ERR(priv->tx_tfm_mic)) {
        printk(KERN_DEBUG "orinoco_mic_init: could not allocate "
               "crypto API michael_mic\n");
        priv->tx_tfm_mic = NULL;
        return -ENOMEM;
    }

    priv->rx_tfm_mic = crypto_alloc_hash("michael_mic", 0, 0);
    if (IS_ERR(priv->rx_tfm_mic)) {
        printk(KERN_DEBUG "orinoco_mic_init: could not allocate "
               "crypto API michael_mic\n");
        priv->rx_tfm_mic = NULL;
        return -ENOMEM;
    }

    return 0;
}

void orinoco_mic_free(struct orinoco_private *priv)
{
    if (priv->tx_tfm_mic)
        crypto_free_hash(priv->tx_tfm_mic);
    if (priv->rx_tfm_mic)
        crypto_free_hash(priv->rx_tfm_mic);
}

int orinoco_mic(struct crypto_hash *tfm_michael, u8 *key,
        u8 *da, u8 *sa, u8 priority,
        u8 *data, size_t data_len, u8 *mic)
{
    struct hash_desc desc;
    struct scatterlist sg[2];
    u8 hdr[ETH_HLEN + 2]; /* size of header + padding */

    if (tfm_michael == NULL) {
        printk(KERN_WARNING "orinoco_mic: tfm_michael == NULL\n");
        return -1;
    }

    /* Copy header into buffer. We need the padding on the end zeroed */
    memcpy(&hdr[0], da, ETH_ALEN);
    memcpy(&hdr[ETH_ALEN], sa, ETH_ALEN);
    hdr[ETH_ALEN * 2] = priority;
    hdr[ETH_ALEN * 2 + 1] = 0;
    hdr[ETH_ALEN * 2 + 2] = 0;
    hdr[ETH_ALEN * 2 + 3] = 0;

    /* Use scatter gather to MIC header and data in one go */
    sg_init_table(sg, 2);
    sg_set_buf(&sg[0], hdr, sizeof(hdr));
    sg_set_buf(&sg[1], data, data_len);

    if (crypto_hash_setkey(tfm_michael, key, MIC_KEYLEN))
        return -1;

    desc.tfm = tfm_michael;
    desc.flags = 0;
    return crypto_hash_digest(&desc, sg, data_len + sizeof(hdr),
                  mic);
}