Improved Pyscript Auth Module

Auth plugin can use any kind of credentials now: the python script takes a set of Java credential objects (instead of native Python primitives). No conversion takes place, Python scripts need to be written such that they can deal with the Java objects themselves. - Added documentation to TheBook - Made the module configurable (workdir can be set via `gplazma.pyscript.workdir`) Signed-off-by: Anton Schwarz [email protected]
khys95 · Aug 9, 2024 · 591e361 · 591e361
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diff --git a/docs/TheBook/src/main/markdown/config-gplazma.md b/docs/TheBook/src/main/markdown/config-gplazma.md
@@ -556,6 +556,40 @@ In the OP definition:
     allows for custom behaviour if the token is adhering to dCache's
     authorisation model.
 
+##### pyscript
+
+A gplazma2 auth module which uses the Jython package to run Python files
+from within the Java runtime used for dCache. It is intended for site
+admins who want to quickly script authentication plugins without needing
+to understand or write the native dCache Java code.
+
+*Implementation Details*
+
+Jython limits the Python version to version 2.7. Multiple files can be inserted which will
+be executed sequentially but in no particular order.
+
+Each Python file shall be structured to contain one function `py_auth(public_credentials, private_credentials,
+principals)` which returns a boolean whether the authentication was successful. Returning `False` will trigger an
+`AuthenticationException` in Java. Each parameter passed to `py_auth` will be a Python set.
+
+- `private_credentials` is a set of Java credential objects.
+- `public_credentials` is the same as `private_credentials`
+- `principals` will be a set of strings in the form `<principal_type>:<value>`, i.e. a pair of strings separated by a
+  colon. Consider `org.dcache.auth.Subjects#principalsFromArgs` to see how the principal type string maps to the
+  principals classes.
+
+The conversion from a set of principals to a set of strings is done entirely within the `authenticate` method of the
+`PyscriptPlugin`-class. The Python file only ever sees a set of strings, while someone using the plugin will only ever
+need to pass a set of principals from within Java. The conversion is done using existing functions.
+
+You will need to write Python code to handle the credentials properly. Note that the credentials will *not* come as
+primitives but as objects. Read the [Jython](https://javadoc.io/doc/org.python/jython/latest/index.html) documentation
+on how to handle Java objects from within Python.
+
+You will need to set the property `gplazma.pyscript.workdir` which tells the interpreter where to search for the Python
+files.
+
+
 
 #### map Plug-ins
 

diff --git a/modules/gplazma2-pyscript/gplazma2-pyscript/sample_plugin.py b/modules/gplazma2-pyscript/gplazma2-pyscript/sample_plugin.py
@@ -4,7 +4,8 @@ def py_auth(public_credentials, private_credentials, principals):
     :param public_credentials: set of public auth credentials
     :param private_credentials: set of private auth credentials
     :param principals: set of principals (string values)
-    :return: boolean whether authentication is permitted
+    :return: boolean whether authentication is permitted. The principals are
+             changed as a side effect.
 
     Note that the set of principals may only be added to, existing principals
     may never be removed!
@@ -13,27 +14,22 @@ def py_auth(public_credentials, private_credentials, principals):
     org.dcache.auth.Subjects#principalsFromArgs how these are converted back
     into principals in Java.
 
-    In case authentication is denied, we return None.
-
-    In this sample implementation, the following logic is used:
-    AUTHENTICATE:
-        Condition:
-        - Either "Tom" is in the public credentials
-        - Or "Rose" is in the set of private credentials
-        Result:
-        - the username principal "Joad" is added (as string "username:joad")
-        - we return True
-    REFUSE:
-        Condition:
-        - Either "Connie" is in either one of the credentials
-        - No passing condition from above is met
-        Result:
-        - we return False
+    In case authentication is denied, we return False.
     """
-    if ("Connie" in public_credentials) or ("Connie" in private_credentials):
-        return False
-    elif ("Tom" in public_credentials) or ("Rose" in private_credentials):
-        principals.add("username:Joad")
-        return True
-    else:
-        return False
+    list_accepted = [
+        ("admin", "dickerelch"),
+        ("Dust", "Bowl")
+    ]
+    for pubcred in public_credentials:
+        # public credentials iterated in random order
+        # first username:password combination in list of accepted credentials leads to acceptance
+        if (pubcred.getUsername(), pubcred.getPassword()) in list_accepted:
+            principals.add("username:%s" % (pubcred.getUsername()))  # Python 2-style String formatting
+            return True
+    for privcred in private_credentials:
+        # public credentials iterated in random order
+        # first username:password combination in list of accepted credentials leads to acceptance
+        if (privcred.getUsername(), privcred.getPassword()) in list_accepted:
+            principals.add("username:%s" % (privcred.getUsername()))  # Python 2-style String formatting
+            return True
+    return False
diff --git a/modules/gplazma2-pyscript/src/main/java/org/dcache/gplazma/pyscript/PyscriptPlugin.java b/modules/gplazma2-pyscript/src/main/java/org/dcache/gplazma/pyscript/PyscriptPlugin.java
@@ -6,11 +6,7 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.security.Principal;
-import java.util.Set;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Properties;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import org.dcache.auth.Subjects;
@@ -29,12 +25,14 @@ public class PyscriptPlugin implements GPlazmaAuthenticationPlugin {
     private static final Logger LOGGER = LoggerFactory.getLogger(PyscriptPlugin.class);
 
     private final PythonInterpreter PI = new PythonInterpreter();
+    private final String pluginDirectoryString;
     private List<Path> pluginPathList = new ArrayList<>();
 
     public PyscriptPlugin(Properties properties) {
         // constructor
+        pluginDirectoryString = properties.getProperty("gplazma.pyscript.workdir");
         try {
-            pluginPathList = listDirectoryContents("gplazma2-pyscript");  // TODO fix this, currently just reads from local folder
+            pluginPathList = listDirectoryContents(pluginDirectoryString);
         } catch (IOException e) {
             LOGGER.error("Error reading Pyscript directory");
         }
@@ -49,7 +47,6 @@ public void authenticate(
             Set<Object> privateCredentials,
             Set<Principal> principals
     ) throws AuthenticationException {
-
         for (Path pluginPath : pluginPathList) {
             // for each path in pluginPathList
             try {
@@ -72,44 +69,20 @@ public void authenticate(
                 PySet pyPrivateCredentials = new PySet();
                 PySet pyPrincipals = new PySet();
 
-                // Only handle select datatypes
-                for (Object pubCred : publicCredentials) {
-                    if (
-                            pubCred instanceof String
-                            || pubCred instanceof Number // all number datatypes
-                    ) {
-                        pyPublicCredentials.add(pubCred);
-                    } else {
-                        LOGGER.warn(
-                            "gplazma2-pyscript: Public Credential {} dropped. Use String or Number.",
-                            pubCred
-                        );
-                    }
-                }
-                for (Object privCred : privateCredentials) {
-                    if (
-                        privCred instanceof String
-                        || privCred instanceof Number // all number datatypes
-                    ) {
-                        pyPrivateCredentials.add(privCred);
-                    } else {
-                        LOGGER.warn(
-                            "gplazma2-pyscript: Private Credential {} dropped. Use String or Number.",
-                            privCred.toString()
-                        );
-                    }
-                }
+                // add credentials regardless of type -> type handling is done in Python!
+                pyPublicCredentials.addAll(publicCredentials);
+                pyPrivateCredentials.addAll(privateCredentials);
 
                 // Convert principals into string representation
-                String principalsString = Subjects.toString(
-                    Subjects.ofPrincipals(principals)
-                );
-                String[] principalStringList = principalsString.substring(
-                    1, principalsString.length() - 1
-                ).split(", ");
-                pyPrincipals.addAll(Arrays.asList(principalStringList));
-
-
+                if (!principals.isEmpty()) {
+                    String principalsString = Subjects.toString(
+                            Subjects.ofPrincipals(principals)
+                    );
+                    String[] principalStringList = principalsString.substring(
+                            1, principalsString.length() - 1
+                    ).split(", ");
+                    pyPrincipals.addAll(Arrays.asList(principalStringList));
+                }
 
                 // =============
                 // Run in Python
@@ -136,11 +109,11 @@ public void authenticate(
                 // update principals
                 // =================
                 // Convert principals back from string representation
-                List<String> convertedPyPrincipals = List.copyOf(pyPrincipals);
-
-                // Update original Principals
-                principals.addAll(Subjects.principalsFromArgs(convertedPyPrincipals));
-
+                if (!pyPrincipals.isEmpty()) {
+                    List<String> convertedPyPrincipals = List.copyOf(pyPrincipals);
+                    // Update original Principals
+                    principals.addAll(Subjects.principalsFromArgs(convertedPyPrincipals));
+                }
             } catch (IOException e) {
                 throw new AuthenticationException(
                     "Authentication failed due to I/O error: " + e.getMessage(), e

diff --git a/modules/gplazma2-pyscript/src/test/java/org/dcache/gplazma/pyscript/PyscriptPluginTest.java b/modules/gplazma2-pyscript/src/test/java/org/dcache/gplazma/pyscript/PyscriptPluginTest.java
@@ -6,6 +6,7 @@
 import java.security.Principal;
 import java.util.*;
 
+import org.dcache.auth.PasswordCredential;
 import org.dcache.auth.UserNamePrincipal;
 import org.dcache.gplazma.AuthenticationException;
 import org.junit.Before;
@@ -25,15 +26,14 @@ This module reads the Python (2.7) files provided and runs each auth attempt
 
     AUTHENTICATE:
         Condition:
-        - Either "Tom" is in the public credentials
-        - Or "Rose" is in the set of private credentials
+        - public_credentials contains at least one username:password combination
+        that is accepted (admin:dickerelch, Dust:Bowl)
         Result:
-        - the username principal "Joad" is added (as string "username:joad")
+        - We add the username principal corresponding to the accepted username
         - we return True
     REFUSE:
         Condition:
-        - Either "Connie" is in either one of the credentials
-        - No passing condition from above is met
+        - The above condition is not met.
         Result:
         - we return False
 
@@ -44,61 +44,58 @@ This module reads the Python (2.7) files provided and runs each auth attempt
 
     @Before
     public void setUp() {
-        plugin = new PyscriptPlugin(new Properties());
+        // Properties
+        Properties properties = new Properties();
+        properties.setProperty("gplazma.pyscript.workdir", "gplazma2-pyscript");
+        plugin = new PyscriptPlugin(properties);
     }
 
     @Test
-    public void passesWithPublicCredential() throws Exception {
+    public void passesWithPasswordCredential() throws Exception {
+        // Credentials
+        PasswordCredential pwcred = new PasswordCredential("Dust", "Bowl");
         Set<Object> publicCredentials = new HashSet<>();
-        publicCredentials.add("Tom");
+        publicCredentials.add(pwcred);
+
+        // Principals
         Set<Principal> principals = new HashSet<>();
-        principals.add(new UserNamePrincipal("Casy"));
+        principals.add(new UserNamePrincipal("joad"));
+
+        // Execution
         plugin.authenticate(
                 publicCredentials,
                 Collections.emptySet(),
                 principals
         );
-        assertThat(principals, hasItems(
-                new UserNamePrincipal("Joad"), // new principal added by plugin
-                new UserNamePrincipal("Casy")  // old principal still included
-        ));
-    }
 
-    @Test
-    public void passesWithPrivateCredential() throws Exception {
-        Set<Object> privateCredentials = new HashSet<>();
-        privateCredentials.add("Rose");
-        Set<Principal> principals = new HashSet<>();
-        principals.add(new UserNamePrincipal("Casy"));
-        plugin.authenticate(
-                Collections.emptySet(),
-                privateCredentials,
-                principals
-        );
+        // Assert that principals has been added to
         assertThat(principals, hasItems(
-                new UserNamePrincipal("Joad"), // new principal added by plugin
-                new UserNamePrincipal("Casy")  // old principal still included
+                new UserNamePrincipal("Dust"),
+                new UserNamePrincipal("joad")
         ));
     }
 
     @Test(expected = AuthenticationException.class)
-    public void failsOnNoParameters() throws Exception{
+    public void failsOnBadPasswordCredential() throws Exception {
+        // Credentials
+        PasswordCredential pwcred = new PasswordCredential("Dustin", "Hoffman");
+        Set<Object> publicCredentials = new HashSet<>();
+        publicCredentials.add(pwcred);
+
+        // Execution
         plugin.authenticate(
-                Collections.emptySet(),
+                publicCredentials,
                 Collections.emptySet(),
                 Collections.emptySet()
         );
     }
 
     @Test(expected = AuthenticationException.class)
-    public void failsOnNoParametersDespitePrincipals() throws Exception {
-        Set<Principal> principals = new HashSet<>();
-        principals.add(new UserNamePrincipal("Ruthie"));
-        principals.add(new UserNamePrincipal("Casy"));
+    public void failsOnNoParameters() throws Exception{
         plugin.authenticate(
                 Collections.emptySet(),
                 Collections.emptySet(),
-                principals
+                Collections.emptySet()
         );
     }
 }
diff --git a/packages/pom.xml b/packages/pom.xml
@@ -190,6 +190,11 @@
       <artifactId>gplazma2-htpasswd</artifactId>
       <version>${project.version}</version>
     </dependency>
+      <dependency>
+          <groupId>org.dcache</groupId>
+          <artifactId>gplazma2-pyscript</artifactId>
+          <version>10.2.0-SNAPSHOT</version>
+      </dependency>
       <dependency>
           <groupId>org.dcache</groupId>
           <artifactId>dcache-frontend</artifactId>