k8s: Validate API server excluded admission plugins

This patch verifies if CIS Kubernetes Benchmark v1.3.0 section
regarding master node configuration is satisfied (1.1.10).

However, CIS Kubernetes Benchmark v1.3.0 mismatches official
documentation: Kubernetes 1.10+ already provides safe defaults from
security standpoint [1] (ONAP Casablanca uses 1.11).

Deprecated admission control plugin flag has also been validated since
it was still available in Kubernetes provided by Rancher [2].

[1] https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/#is-there-a-recommended-set-of-admission-controllers-to-use
[2] https://github.com/rancher/rancher/issues/15064

Issue-ID: SECCOM-235
Change-Id: I0e8fe9f885861f155cb8265df085fa93dbdff6d2
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/test/security/k8s/src/check/validators/master/api.go b/test/security/k8s/src/check/validators/master/api.go
index c91b77e30..58064ef10 100644
--- a/test/security/k8s/src/check/validators/master/api.go
+++ b/test/security/k8s/src/check/validators/master/api.go
@@ -126,3 +126,39 @@ func hasFlagValidPort(flag string, params []string) bool {
 	}
 	return true
 }
+
+// IsAlwaysAdmitAdmissionControlPluginExcluded validates AlwaysAdmit is excluded from admission control plugins.
+func IsAlwaysAdmitAdmissionControlPluginExcluded(params []string) bool {
+	if isSingleFlagPresent("--enable-admission-plugins=", params) {
+		return !hasFlagArgumentIncluded("--enable-admission-plugins=", "AlwaysAdmit", params)
+	}
+	if isSingleFlagPresent("--admission-control=", params) {
+		return !hasFlagArgumentIncluded("--admission-control=", "AlwaysAdmit", params)
+	}
+	return false
+}
+
+// isSingleFlagPresent checks presence of selected flag and whether it was used once.
+func isSingleFlagPresent(flag string, params []string) bool {
+	found := filterFlags(params, flag)
+	if len(found) != 1 {
+		return false
+	}
+	return true
+}
+
+// hasFlagArgumentIncluded checks whether selected flag includes requested argument.
+func hasFlagArgumentIncluded(flag string, argument string, params []string) bool {
+	found := filterFlags(params, flag)
+	if len(found) != 1 {
+		return false
+	}
+
+	_, values := splitKV(found[0], "=")
+	for _, v := range strings.Split(values, ",") {
+		if v == argument {
+			return true
+		}
+	}
+	return false
+}