evm: key must be set once during initialization
Dmitry Kasatkin [Mon, 5 Dec 2011 11:17:41 +0000 (13:17 +0200)]
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: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/integrity/evm/evm_crypto.c

index 847a2d7..3b9f5a0 100644 (file)
@@ -52,6 +52,14 @@ static struct shash_desc *init_desc(const char type)
                        *tfm = NULL;
                        return ERR_PTR(rc);
                }
+               if (type == EVM_XATTR_HMAC) {
+                       rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
+                       if (rc) {
+                               crypto_free_shash(*tfm);
+                               *tfm = NULL;
+                               return ERR_PTR(rc);
+                       }
+               }
        }
 
        desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
@@ -62,14 +70,7 @@ static struct shash_desc *init_desc(const char type)
        desc->tfm = *tfm;
        desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
-       if (type == EVM_XATTR_HMAC) {
-               rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
-               if (rc)
-                       goto out;
-       }
-
        rc = crypto_shash_init(desc);
-out:
        if (rc) {
                kfree(desc);
                return ERR_PTR(rc);