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Issue#2834: Agent Impersonation via JENKINS_SECRET #2836

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Issue#2834: Agent Impersonation via JENKINS_SECRET #2836

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44 changes: 44 additions & 0 deletions src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesLauncher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,10 @@
import hudson.slaves.SlaveComputer;
import io.fabric8.kubernetes.api.model.ContainerStatus;
import io.fabric8.kubernetes.api.model.ObjectMeta;
import io.fabric8.kubernetes.api.model.OwnerReferenceBuilder;
import io.fabric8.kubernetes.api.model.Pod;
import io.fabric8.kubernetes.api.model.Secret;
import io.fabric8.kubernetes.api.model.SecretBuilder;
import io.fabric8.kubernetes.client.KubernetesClient;
import io.fabric8.kubernetes.client.KubernetesClientException;
import java.io.IOException;
Expand Down Expand Up @@ -218,9 +221,12 @@ public synchronized void launch(SlaveComputer computer, TaskListener listener) {
} else {
LOGGER.log(INFO, () -> "Pod already exists: " + cloudName + " " + namespace + "/" + podName);
listener.getLogger().printf("Pod already exists: %s %s/%s%n", cloudName, namespace, podName);
pod = existingPod;
}
kubernetesComputer.setLaunching(true);

createJnlpSecret(client, pod, kubernetesComputer.getJnlpMac());

ObjectMeta podMetadata = pod.getMetadata();
template.getWorkspaceVolume().createVolume(client, podMetadata);
template.getVolumes().forEach(volume -> volume.createVolume(client, podMetadata));
Expand Down Expand Up @@ -334,6 +340,44 @@ public synchronized void launch(SlaveComputer computer, TaskListener listener) {
}
}

/**
* Create a per-agent Kubernetes Secret holding the JNLP HMAC, owned by the Pod so it is
* garbage-collected with it. The Secret is referenced by the jnlp container via secretKeyRef,
* so the value never appears in the PodSpec.
*/
private static void createJnlpSecret(KubernetesClient client, Pod pod, String jnlpMac) {
String namespace = pod.getMetadata().getNamespace();
String secretName = pod.getMetadata().getName() + PodTemplateBuilder.JNLP_SECRET_NAME_SUFFIX;
Secret secret = new SecretBuilder()
.withNewMetadata()
.withName(secretName)
.withNamespace(namespace)
.addToOwnerReferences(new OwnerReferenceBuilder()
.withApiVersion("v1")
.withKind("Pod")
.withName(pod.getMetadata().getName())
.withUid(pod.getMetadata().getUid())
.withController(true)
.withBlockOwnerDeletion(true)
.build())
.endMetadata()
.withType("Opaque")
.addToStringData(PodTemplateBuilder.JNLP_SECRET_KEY, jnlpMac)
.build();
try {
client.secrets().inNamespace(namespace).create(secret);
LOGGER.log(FINE, () -> "Created JNLP Secret: " + namespace + "/" + secretName);
} catch (KubernetesClientException e) {
if (e.getCode() == 409) {
// Already exists from a previous launcher attempt; the JNLP mac is deterministic
// per agent identity, so the existing value is still valid.
LOGGER.log(FINE, () -> "JNLP Secret already exists, reusing: " + namespace + "/" + secretName);
} else {
throw e;
}
}
}

private static void terminateOrLog(KubernetesSlave node) {
try {
node.terminate();
Expand Down
28 changes: 26 additions & 2 deletions src/main/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@
import io.fabric8.kubernetes.api.model.ContainerPort;
import io.fabric8.kubernetes.api.model.EnvVar;
import io.fabric8.kubernetes.api.model.EnvVarBuilder;
import io.fabric8.kubernetes.api.model.EnvVarSourceBuilder;
import io.fabric8.kubernetes.api.model.ExecAction;
import io.fabric8.kubernetes.api.model.LocalObjectReference;
import io.fabric8.kubernetes.api.model.Pod;
Expand All @@ -48,6 +49,7 @@
import io.fabric8.kubernetes.api.model.Quantity;
import io.fabric8.kubernetes.api.model.ResourceRequirements;
import io.fabric8.kubernetes.api.model.ResourceRequirementsBuilder;
import io.fabric8.kubernetes.api.model.SecretKeySelectorBuilder;
import io.fabric8.kubernetes.api.model.Volume;
import io.fabric8.kubernetes.api.model.VolumeBuilder;
import io.fabric8.kubernetes.api.model.VolumeMount;
Expand Down Expand Up @@ -96,6 +98,10 @@ public class PodTemplateBuilder {
public static final Pattern FROM_DIRECTIVE = Pattern.compile("^FROM (.*)$");

public static final String LABEL_KUBERNETES_CONTROLLER = "kubernetes.jenkins.io/controller";

public static final String JNLP_SECRET_NAME_SUFFIX = "-jnlp-secret";
public static final String JNLP_SECRET_KEY = "jenkins-secret";

static final String NO_RECONNECT_AFTER_TIMEOUT =
SystemProperties.getString(PodTemplateBuilder.class.getName() + ".noReconnectAfter", "1d");
private static final String JENKINS_AGENT_FILE_ENVVAR = "JENKINS_AGENT_FILE";
Expand Down Expand Up @@ -467,8 +473,9 @@ private Map<String, EnvVar> agentEnvVars(String workingDir) {
if (agent != null) {
SlaveComputer computer = agent.getComputer();
if (computer != null) {
// Add some default env vars for Jenkins
env.put("JENKINS_SECRET", computer.getJnlpMac());
// JENKINS_SECRET is injected via a per-agent Kubernetes Secret (see KubernetesLauncher)
// so the literal value never appears in the PodSpec, where anyone with
// `get pods` could read it.
// JENKINS_AGENT_NAME is default in jnlp-slave
// JENKINS_NAME only here for backwords compatability
env.put("JENKINS_NAME", computer.getName());
Expand Down Expand Up @@ -503,9 +510,26 @@ private Map<String, EnvVar> agentEnvVars(String workingDir) {
Map<String, EnvVar> envVarsMap = new HashMap<>();

env.entrySet().forEach(item -> envVarsMap.put(item.getKey(), new EnvVar(item.getKey(), item.getValue(), null)));

if (agent != null && agent.getComputer() != null) {
envVarsMap.put("JENKINS_SECRET", buildJnlpSecretEnvVar(agent.getComputer().getName()));
}
return envVarsMap;
}

private static EnvVar buildJnlpSecretEnvVar(String agentName) {
return new EnvVarBuilder()
.withName("JENKINS_SECRET")
.withValueFrom(new EnvVarSourceBuilder()
.withSecretKeyRef(new SecretKeySelectorBuilder()
.withName(agentName + JNLP_SECRET_NAME_SUFFIX)
.withKey(JNLP_SECRET_KEY)
.withOptional(false)
.build())
.build())
.build();
}

private Container createContainer(
ContainerTemplate containerTemplate,
Collection<TemplateEnvVar> globalEnvVars,
Expand Down
14 changes: 13 additions & 1 deletion src/test/java/org/csanchez/jenkins/plugins/kubernetes/PodTemplateBuilderTest.java
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Expand Up @@ -13,6 +13,9 @@

import io.fabric8.kubernetes.api.model.Container;
import io.fabric8.kubernetes.api.model.EnvVar;
import io.fabric8.kubernetes.api.model.EnvVarBuilder;
import io.fabric8.kubernetes.api.model.EnvVarSourceBuilder;
import io.fabric8.kubernetes.api.model.SecretKeySelectorBuilder;
import io.fabric8.kubernetes.api.model.Pod;
import io.fabric8.kubernetes.api.model.PodSecurityContext;
import io.fabric8.kubernetes.api.model.Quantity;
Expand Down Expand Up @@ -476,7 +479,16 @@ private void validateJnlpContainer(Container jnlp, KubernetesSlave slave, boolea
} else {
envVars.add(new EnvVar("JENKINS_URL", JENKINS_URL, null));
}
envVars.add(new EnvVar("JENKINS_SECRET", AGENT_SECRET, null));
envVars.add(new EnvVarBuilder()
.withName("JENKINS_SECRET")
.withValueFrom(new EnvVarSourceBuilder()
.withSecretKeyRef(new SecretKeySelectorBuilder()
.withName(AGENT_NAME + JNLP_SECRET_NAME_SUFFIX)
.withKey(JNLP_SECRET_KEY)
.withOptional(false)
.build())
.build())
.build());
envVars.add(new EnvVar("JENKINS_NAME", AGENT_NAME, null));
envVars.add(new EnvVar("JENKINS_AGENT_NAME", AGENT_NAME, null));
envVars.add(new EnvVar("JENKINS_AGENT_WORKDIR", ContainerTemplate.DEFAULT_WORKING_DIR, null));
Expand Down