ima: limit file hash setting by user to fix and log modes

File hashes are automatically set and updated and should not be
manually set. This patch limits file hash setting to fix and log
modes.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 4df493e..1873b55 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -378,10 +378,14 @@
 	result = ima_protect_xattr(dentry, xattr_name, xattr_value,
 				   xattr_value_len);
 	if (result == 1) {
+		bool digsig;
+
 		if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
 			return -EINVAL;
-		ima_reset_appraise_flags(d_backing_inode(dentry),
-			 (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
+		digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
+		if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
+			return -EPERM;
+		ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
 		result = 0;
 	}
 	return result;