evm: key must be set once during initialization

On multi-core systems, setting of the key before every caclculation,
causes invalid HMAC calculation for other tfm users, because internal
state (ipad, opad) can be invalid before set key call returns.
It needs to be set only once during initialization.
Signed-off-by: NDmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: NMimi Zohar <zohar@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

security/integrity/evm/evm_crypto.c

@@ -41,6 +41,12 @@ static struct shash_desc *init_desc(void)
 			hmac_tfm = NULL;
 			return ERR_PTR(rc);
 		}
+		rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len);
+		if (rc) {
+			crypto_free_shash(hmac_tfm);
+			hmac_tfm = NULL;
+			return ERR_PTR(rc);
+		}
 	}
 
 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac_tfm),
@@ -51,11 +57,7 @@ static struct shash_desc *init_desc(void)
 	desc->tfm = hmac_tfm;
 	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len);
-	if (rc)
-		goto out;
 	rc = crypto_shash_init(desc);
-out:
 	if (rc) {
 		kfree(desc);
 		return ERR_PTR(rc);