From 9881bf4a8f7048dd7abff0df3dfb6cd449b42540 Mon Sep 17 00:00:00 2001
From: Eirik Nygaard <eirik.nygaard@yahooinc.com>
Date: Wed, 9 Aug 2023 15:51:51 +0200
Subject: WIP: GcpCredentials retriever

---
 .../com/yahoo/vespa/athenz/gcp/GcpCredentials.java | 96 ++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 vespa-athenz/src/main/java/com/yahoo/vespa/athenz/gcp/GcpCredentials.java

(limited to 'vespa-athenz/src')

diff --git a/vespa-athenz/src/main/java/com/yahoo/vespa/athenz/gcp/GcpCredentials.java b/vespa-athenz/src/main/java/com/yahoo/vespa/athenz/gcp/GcpCredentials.java
new file mode 100644
index 00000000000..9dcccd52b09
--- /dev/null
+++ b/vespa-athenz/src/main/java/com/yahoo/vespa/athenz/gcp/GcpCredentials.java
@@ -0,0 +1,96 @@
+package com.yahoo.vespa.athenz.gcp;
+
+import com.google.api.client.http.apache.v2.ApacheHttpTransport;
+import com.google.auth.http.HttpTransportFactory;
+import com.google.auth.oauth2.ExternalAccountCredentials;
+import com.yahoo.athenz.auth.util.Crypto;
+import com.yahoo.slime.Cursor;
+import com.yahoo.slime.Slime;
+import com.yahoo.slime.SlimeUtils;
+import com.yahoo.vespa.athenz.api.AthenzDomain;
+import com.yahoo.vespa.athenz.identity.ServiceIdentityProvider;
+import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
+import org.apache.http.impl.client.HttpClientBuilder;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URLEncoder;
+import java.nio.charset.StandardCharsets;
+
+public class GcpCredentials {
+    final private static String WORKLOAD_POOL_NAME = "athenz";
+    final private static String WORKLOAD_PROVIDER_NAME = "athenz";
+
+    final private InputStream tokenApiStream;
+    private final HttpTransportFactory httpTransportFactory;
+
+    public GcpCredentials(String ztsUrl, ServiceIdentityProvider provider, String redirectURISuffix, int tokenLifetimeSeconds, AthenzDomain athenzDomain, String gcpRole, String projectName, String projectNumber, String serviceAccountName) {
+        String clientId = athenzDomain.getName() + ".gcp";
+        final String audience = String.format("//iam.googleapis.com/projects/%s/locations/global/workloadIdentityPools/%s/providers/%s",
+                projectNumber, WORKLOAD_POOL_NAME, WORKLOAD_PROVIDER_NAME);
+        final String serviceUrl = String.format("https://iamcredentials.googleapis.com/v1/projects/-/serviceAccounts/%s@%s.iam.gserviceaccount.com:generateAccessToken",
+                serviceAccountName, projectName);
+        final String scope = URLEncoder.encode(generateIdTokenScope(athenzDomain.getName(), gcpRole), StandardCharsets.UTF_8);
+        final String redirectUri = URLEncoder.encode(generateRedirectUri(clientId, redirectURISuffix), StandardCharsets.UTF_8);
+        final String tokenUrl = String.format("%s/oauth2/auth?response_type=id_token&client_id=%s&redirect_uri=%s&scope=%s&nonce=%s&keyType=EC&fullArn=true&output=json",
+                ztsUrl, clientId, redirectUri, scope, Crypto.randomSalt());
+
+        tokenApiStream = createTokenAPIStream(audience, serviceUrl, tokenUrl, tokenLifetimeSeconds);
+        SSLConnectionSocketFactory sslConnectionSocketFactory = new SSLConnectionSocketFactory(provider.getIdentitySslContext());
+        HttpClientBuilder httpClientBuilder = ApacheHttpTransport.newDefaultHttpClientBuilder()
+                .setSSLSocketFactory(sslConnectionSocketFactory);
+        httpTransportFactory = () -> new ApacheHttpTransport(httpClientBuilder.build());
+    }
+
+    public ExternalAccountCredentials getCredential() throws IOException {
+        return ExternalAccountCredentials.fromStream(tokenApiStream, httpTransportFactory);
+    }
+
+    private InputStream createTokenAPIStream(final String audience, final String serviceUrl, final String tokenUrl,
+                                     int tokenLifetimeSeconds) {
+
+        Slime root = new Slime();
+        Cursor c = root.setObject();
+
+        c.setString("type", "external_account");
+        c.setString("audience", audience);
+        c.setString("subject_token_type", "urn:ietf:params:oauth:token-type:jwt");
+        c.setString("token_url", "https://sts.googleapis.com/v1/token");
+
+        c.setString("service_account_impersonation_url", serviceUrl);
+        Cursor sai = c.setObject("service_account_impersonation");
+        sai.setLong("token_lifetime_seconds", tokenLifetimeSeconds);
+
+        Cursor credentialSource = c.setObject("credential_source");
+        credentialSource.setString("url", tokenUrl);
+
+        Cursor credentialSourceFormat = credentialSource.setObject("format");
+        credentialSourceFormat.setString("type", "json");
+        credentialSourceFormat.setString("subject_token_field_name", "id_token");
+
+        try {
+            return new ByteArrayInputStream(SlimeUtils.toJsonBytes(root));
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static String generateIdTokenScope(final String domainName, String roleName) {
+        StringBuilder scope = new StringBuilder(256);
+        scope.append("openid");
+        scope.append(' ').append(domainName).append(":role.").append(roleName);
+        return scope.toString();
+    }
+
+    public static String generateRedirectUri(final String clientId, String uriSuffix) {
+        int idx = clientId.lastIndexOf('.');
+        if (idx == -1) {
+            return "";
+        }
+        final String dashDomain = clientId.substring(0, idx).replace('.', '-');
+        final String service = clientId.substring(idx + 1);
+        return "https://" + service + "." + dashDomain + "." + uriSuffix;
+    }
+
+}
-- 
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