On Wed, Feb 3, 2016 at 9:06 PM, Mimi Zohar <zohar at linux.vnet.ibm.com> wrote:
> Setting up ahash has some overhead. Only use ahash to calculate the
> hash of a buffer, if the buffer is larger than ima_ahash_minsize.
>
> Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin at huawei.com>
> ---
> security/integrity/ima/ima_crypto.c | 75 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
> index fccb6ce..38f2ed8 100644
> --- a/security/integrity/ima/ima_crypto.c
> +++ b/security/integrity/ima/ima_crypto.c
> @@ -519,6 +519,63 @@ int ima_calc_field_array_hash(struct ima_field_data *field_data,
> return rc;
> }
>
> +static int calc_buffer_ahash_atfm(const void *buf, loff_t len,
> + struct ima_digest_data *hash,
> + struct crypto_ahash *tfm)
> +{
> + struct ahash_request *req;
> + struct scatterlist sg;
> + struct ahash_completion res;
> + int rc, ahash_rc = 0;
> +
> + hash->length = crypto_ahash_digestsize(tfm);
> +
> + req = ahash_request_alloc(tfm, GFP_KERNEL);
> + if (!req)
> + return -ENOMEM;
> +
> + init_completion(&res.completion);
> + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
> + CRYPTO_TFM_REQ_MAY_SLEEP,
> + ahash_complete, &res);
> +
> + rc = ahash_wait(crypto_ahash_init(req), &res);
> + if (rc)
> + goto out;
> +
> + sg_init_one(&sg, buf, len);
> + ahash_request_set_crypt(req, &sg, NULL, len);
> +
> + ahash_rc = crypto_ahash_update(req);
> +
> + /* wait for the update request to complete */
> + rc = ahash_wait(ahash_rc, &res);
> + if (!rc) {
> + ahash_request_set_crypt(req, NULL, hash->digest, 0);
> + rc = ahash_wait(crypto_ahash_final(req), &res);
> + }
> +out:
> + ahash_request_free(req);
> + return rc;
> +}
> +
> +static int calc_buffer_ahash(const void *buf, loff_t len,
> + struct ima_digest_data *hash)
> +{
> + struct crypto_ahash *tfm;
> + int rc;
> +
> + tfm = ima_alloc_atfm(hash->algo);
> + if (IS_ERR(tfm))
> + return PTR_ERR(tfm);
> +
> + rc = calc_buffer_ahash_atfm(buf, len, hash, tfm);
> +
> + ima_free_atfm(tfm);
> +
> + return rc;
> +}
> +
> static int calc_buffer_shash_tfm(const void *buf, loff_t size,
> struct ima_digest_data *hash,
> struct crypto_shash *tfm)
> @@ -550,8 +607,8 @@ static int calc_buffer_shash_tfm(const void *buf, loff_t size,
> return rc;
> }
>
> -int ima_calc_buffer_hash(const void *buf, loff_t len,
> - struct ima_digest_data *hash)
> +static int calc_buffer_shash(const void *buf, loff_t len,
> + struct ima_digest_data *hash)
> {
> struct crypto_shash *tfm;
> int rc;
> @@ -566,6 +623,20 @@ int ima_calc_buffer_hash(const void *buf, loff_t len,
> return rc;
> }
>
> +int ima_calc_buffer_hash(const void *buf, loff_t len,
> + struct ima_digest_data *hash)
> +{
> + int rc;
> +
> + if (ima_ahash_minsize && len >= ima_ahash_minsize) {
> + rc = calc_buffer_ahash(buf, len, hash);
> + if (!rc)
> + return 0;
> + }
> +
> + return calc_buffer_shash(buf, len, hash);
> +}
> +
> static void __init ima_pcrread(int idx, u8 *pcr)
> {
> if (!ima_used_chip)
> --
> 2.1.0
>
--
Thanks,
Dmitry
