aes_glue.c

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/*
 * Glue Code for the asm optimized version of the AES Cipher Algorithm
 */

#include <linux/module.h>
#include <linux/crypto.h>
#include <crypto/aes.h>

#define AES_MAXNR 14

typedef struct {
    unsigned int rd_key[4 *(AES_MAXNR + 1)];
    int rounds;
} AES_KEY;

struct AES_CTX {
    AES_KEY enc_key;
    AES_KEY dec_key;
};

asmlinkage void AES_encrypt(const u8 *in, u8 *out, AES_KEY *ctx);
asmlinkage void AES_decrypt(const u8 *in, u8 *out, AES_KEY *ctx);
asmlinkage int private_AES_set_decrypt_key(const unsigned char *userKey, const int bits, AES_KEY *key);
asmlinkage int private_AES_set_encrypt_key(const unsigned char *userKey, const int bits, AES_KEY *key);

static void aes_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
    struct AES_CTX *ctx = crypto_tfm_ctx(tfm);
    AES_encrypt(src, dst, &ctx->enc_key);
}

static void aes_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
    struct AES_CTX *ctx = crypto_tfm_ctx(tfm);
    AES_decrypt(src, dst, &ctx->dec_key);
}

static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
        unsigned int key_len)
{
    struct AES_CTX *ctx = crypto_tfm_ctx(tfm);

    switch (key_len) {
    case AES_KEYSIZE_128:
        key_len = 128;
        break;
    case AES_KEYSIZE_192:
        key_len = 192;
        break;
    case AES_KEYSIZE_256:
        key_len = 256;
        break;
    default:
        tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
        return -EINVAL;
    }

    if (private_AES_set_encrypt_key(in_key, key_len, &ctx->enc_key) == -1) {
        tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
        return -EINVAL;
    }
    /* private_AES_set_decrypt_key expects an encryption key as input */
    ctx->dec_key = ctx->enc_key;
    if (private_AES_set_decrypt_key(in_key, key_len, &ctx->dec_key) == -1) {
        tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
        return -EINVAL;
    }
    return 0;
}

static struct crypto_alg aes_alg = {
    .cra_name       = "aes",
    .cra_driver_name    = "aes-asm",
    .cra_priority       = 200,
    .cra_flags      = CRYPTO_ALG_TYPE_CIPHER,
    .cra_blocksize      = AES_BLOCK_SIZE,
    .cra_ctxsize        = sizeof(struct AES_CTX),
    .cra_module     = THIS_MODULE,
    .cra_list       = LIST_HEAD_INIT(aes_alg.cra_list),
    .cra_u  = {
        .cipher = {
            .cia_min_keysize    = AES_MIN_KEY_SIZE,
            .cia_max_keysize    = AES_MAX_KEY_SIZE,
            .cia_setkey         = aes_set_key,
            .cia_encrypt        = aes_encrypt,
            .cia_decrypt        = aes_decrypt
        }
    }
};

static int __init aes_init(void)
{
    return crypto_register_alg(&aes_alg);
}

static void __exit aes_fini(void)
{
    crypto_unregister_alg(&aes_alg);
}

module_init(aes_init);
module_exit(aes_fini);

MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm (ASM)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("aes");
MODULE_ALIAS("aes-asm");
MODULE_AUTHOR("David McCullough <[email protected]>");