ima: add support for different security.ima data types

IMA-appraisal currently verifies the integrity of a file based on a
known 'good' measurement value.  This patch reserves the first byte
of 'security.ima' as a place holder for the type of method used for
verifying file data integrity.

Changelog v1:
- Use the newly defined 'struct evm_ima_xattr_data'

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index dac6b68..91ccef1 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -39,7 +39,7 @@
 	struct inode *inode;	/* back pointer to inode in question */
 	u64 version;		/* track inode changes */
 	unsigned char flags;
-	u8 digest[SHA1_DIGEST_SIZE];
+	struct evm_ima_xattr_data ima_xattr;
 	enum integrity_status ima_status;
 	enum integrity_status evm_status;
 };