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>

security/integrity/ima/ima_appraise.c

@@ -378,10 +378,14 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 	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;