[New Rule] Api server first automated rule (1.2.2)

compliance/cis_k8s/rules/cis_1_2_2/rule.rego

@@ -0,0 +1,26 @@
+package compliance.cis_k8s.rules.cis_1_2_2
+
+import data.compliance.cis_k8s
+import data.compliance.lib.common
+import data.compliance.lib.data_adapter
+
+# Ensure that the --basic-auth-file argument is not set (Automated)
+finding = result {
+	command_args := data_adapter.command_args
+	rule_evaluation := common.array_contains(command_args, "--basic-auth-file") == false
+
+	# set result
+	result := {
+		"evaluation": common.calculate_result(rule_evaluation),
+		"evidence": {"command_args": command_args},
+	}
+}
+
+metadata = {
+	"name": "Ensure that the --basic-auth-file argument is not set",
+	"description": "Basic authentication uses plaintext credentials for authentication. Currently, the basic authentication credentials last indefinitely, and the password cannot be changed without restarting the API server. The basic authentication is currently supported for convenience. Hence, basic authentication should not be used.",
+	"impact": "You will have to configure and use alternate authentication mechanisms such as tokens and certificates. Username and password for basic authentication could no longer be used.",
+	"tags": array.concat(cis_k8s.default_tags, ["CIS 1.2.2", "API Server"]),
+	"benchmark": cis_k8s.benchmark_name,
+	"remediation": "Follow the documentation and configure alternate mechanisms for authentication. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and remove the --basic-auth-file=<filename> parameter.",
+}

compliance/cis_k8s/rules/cis_1_2_2/test.rego

@@ -0,0 +1,18 @@
+package compliance.cis_k8s.rules.cis_1_2_2
+
+import data.cis_k8s.test_data
+import data.lib.test
+
+test_violation {
+	test.assert_fail(finding) with input as rule_input("api_server", "--basic-auth-file")
+}
+
+test_pass {
+	test.assert_pass(finding) with input as rule_input("api_server", "")
+}
+
+test_not_evaluated {
+	not finding with input as rule_input("some_process", "")
+}
+
+rule_input(process_type, argument) = test_data.api_server_input(process_type, [argument])

compliance/cis_k8s/test_data.rego

@@ -9,3 +9,9 @@ filesystem_input(filename, mode, uid, gid) = {
 	"uid": uid,
 	"gid": gid,
 }
+
+# Recivies an array of arguments representing the API Server command
+api_server_input(process_type, arguments) = {
+	"type": process_type,
+	"command": concat(" ", array.concat(["kube-apiserver"], arguments)),
+}

compliance/lib/common.rego

@@ -22,6 +22,35 @@ file_permission_match(filemode, user, group, other) {
 	true
 }
 
+array_contains(array, key) {
+	contains(array[_], key)
+} else = false {
+	true
+}
+
+# gets argument's value
+get_arg_value(arguments, key) = value {
+	contains(arguments[i], key)
+	argument := arguments[i]
+	[_, value] := split(argument, "=")
+}
+
+# checks if argument contains value (argument format is csv)
+arg_values_contains(arguments, key, value) {
+	argument := get_arg_value(arguments, key)
+	values := split(argument, ",")
+	value = values[_]
+} else = false {
+	true
+}
+
+# checks if a argument is set to greater value then minimum
+arg_at_least(arguments, key, minimum) {
+	value := get_arg_value(arguments, key)
+	to_number(value) >= minimum
+} else = false {
+	true
+
 # check if file is in path
 file_in_path(path, file_path) {
 	closed_path := concat("", [file_path, "/"]) # make sure last dir name is closed by "/"

compliance/lib/data_adapter.rego

@@ -28,3 +28,13 @@ owner_group_id = gid {
 	is_filesystem
 	gid = input.gid
 }
+
+is_process {
+	input.type == "api_server"
+}
+
+# split the process args string into an array
+command_args = args {
+	is_process
+	args = split(input.command, " ")
+}