GUACAMOLE-1855: Implement bypass and enforcement options in the Duo 2FA module.

extensions/guacamole-auth-duo/pom.xml

@@ -130,6 +130,14 @@
             <version>${kotlin.version}</version>
         </dependency>
 
+        <!-- Library for unified IPv4/6 parsing and validation -->
+        <dependency>
+            <groupId>com.github.seancfoley</groupId>
+            <artifactId>ipaddress</artifactId>
+            <version>5.5.0</version>
+            <scope>provided</scope>
+        </dependency>
+
     </dependencies>
 
 </project>

extensions/guacamole-auth-duo/src/main/java/org/apache/guacamole/auth/duo/UserVerificationService.java

@@ -23,10 +23,13 @@ import com.duosecurity.Client;
 import com.duosecurity.exception.DuoException;
 import com.duosecurity.model.Token;
 import com.google.inject.Inject;
+import inet.ipaddr.IPAddress;
+import inet.ipaddr.IPAddressString;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.Collections;
 import java.util.concurrent.TimeUnit;
+import java.util.List;
 import javax.servlet.http.HttpServletRequest;
 import org.apache.guacamole.GuacamoleException;
 import org.apache.guacamole.GuacamoleServerException;
@@ -107,9 +110,63 @@ public class UserVerificationService {
     public void verifyAuthenticatedUser(AuthenticatedUser authenticatedUser)
             throws GuacamoleException {
 
-        // Ignore anonymous users (unverifiable)
+        // Pull the original HTTP request used to authenticate
+        Credentials credentials = authenticatedUser.getCredentials();
+        HttpServletRequest request = credentials.getRequest();
+        IPAddress clientAddr = new IPAddressString(request.getRemoteAddr()).getAddress();
+
+        // Ignore anonymous users
         String username = authenticatedUser.getIdentifier();
-        if (username.equals(AuthenticatedUser.ANONYMOUS_IDENTIFIER))
+        if (username == null || username.equals(AuthenticatedUser.ANONYMOUS_IDENTIFIER))
+            return;
+        
+        // We enforce by default
+        boolean enforceHost = true;
+        
+        // Check for a list of addresses that should be bypassed and iterate
+        List<IPAddress> bypassAddresses = confService.getBypassHosts();
+        for (IPAddress bypassAddr : bypassAddresses) {
+
+            // If the address contains current client address, flip enforce flag
+            // and break out
+            if (clientAddr != null && clientAddr.isIPAddress()
+                    && bypassAddr.getIPVersion().equals(clientAddr.getIPVersion())
+                    && bypassAddr.contains(clientAddr)) {
+                enforceHost = false;
+                break;
+            }
+        }
+        
+        // Check for a list of addresses that should be enforced and iterate
+        List<IPAddress> enforceAddresses = confService.getEnforceHosts();
+        
+        // Only continue processing if the list is not empty
+        if (!enforceAddresses.isEmpty()) {
+            
+            // If client address is not available or invalid, MFA will
+            // be enforced.
+            if (clientAddr == null || !clientAddr.isIPAddress()) {
+                enforceHost = true;
+            }
+            
+            else {
+                // With addresses set, this default changes to false.
+                enforceHost = false;
+
+                for (IPAddress enforceAddr : enforceAddresses) {
+                    
+                    // If there's a match, flip the enforce flag and break out of the loop
+                    if (enforceAddr.getIPVersion().equals(clientAddr.getIPVersion())
+                            && enforceAddr.contains(clientAddr)) {
+                        enforceHost = true;
+                        break;
+                    }
+                }
+            }
+        }
+            
+        // If the enforce flag has been changed, exit, bypassing Duo MFA.
+        if (!enforceHost)
             return;
 
         // Obtain a Duo client for redirecting the user to the Duo service and
@@ -137,11 +194,6 @@ public class UserVerificationService {
                     + "not currently available (failed health check).", e);
         }
 
-        // Pull the original HTTP request used to authenticate, as well as any
-        // associated credentials
-        Credentials credentials = authenticatedUser.getCredentials();
-        HttpServletRequest request = credentials.getRequest();
-
         // Retrieve signed Duo authentication code and session state from the
         // request (these will be absent if this is an initial authentication
         // attempt and not a redirect back from Duo)

extensions/guacamole-auth-duo/src/main/java/org/apache/guacamole/auth/duo/conf/ConfigurationService.java

@@ -20,10 +20,14 @@
 package org.apache.guacamole.auth.duo.conf;
 
 import com.google.inject.Inject;
+import inet.ipaddr.IPAddress;
 import java.net.URI;
+import java.util.Collections;
+import java.util.List;
 import org.apache.guacamole.GuacamoleException;
 import org.apache.guacamole.environment.Environment;
 import org.apache.guacamole.properties.IntegerGuacamoleProperty;
+import org.apache.guacamole.properties.IPAddressListProperty;
 import org.apache.guacamole.properties.StringGuacamoleProperty;
 import org.apache.guacamole.properties.URIGuacamoleProperty;
 
@@ -105,6 +109,40 @@ public class ConfigurationService {
         public String getName() { return "duo-auth-timeout"; }
                 
     };
+    
+    /**
+     * The optional property that contains a comma-separated list of IP addresses
+     * or CIDRs for which the MFA requirement should be bypassed. If the Duo
+     * extension is installed, any/all users authenticating from clients that
+     * match this list will be able to successfully log in without fulfilling
+     * the MFA requirement. If this option is omitted or is empty, and the
+     * Duo module is installed, all users from all hosts will have Duo MFA
+     * enforced.
+     */
+    private static final IPAddressListProperty DUO_BYPASS_HOSTS =
+            new IPAddressListProperty() {
+    
+        @Override
+        public String getName() { return "duo-bypass-hosts"; }
+                
+    };
+        
+    /**
+     * The optional property that contains a comma-separated list of IP addresses
+     * or CIDRs for which the MFA requirement should be explicitly enforced. If
+     * the Duo module is enabled and this property is specified, users that log
+     * in from hosts that match the items in this list will have Duo MFA required,
+     * and all users from hosts that do not match this list will be able to log
+     * in without the MFA requirement. If this option is missing or empty and
+     * the Duo module is installed, MFA will be enforced for all users.
+     */
+    private static final IPAddressListProperty DUO_ENFORCE_HOSTS =
+            new IPAddressListProperty() {
+    
+        @Override
+        public String getName() { return "duo-enforce-hosts"; }
+                
+    };
 
     /**
      * Returns the hostname of the Duo API endpoint to be used to verify user
@@ -188,5 +226,43 @@ public class ConfigurationService {
     public int getAuthenticationTimeout() throws GuacamoleException {
         return environment.getProperty(DUO_AUTH_TIMEOUT, 5);
     }
+    
+    /**
+     * Returns the list of IP addresses and subnets defined in guacamole.properties
+     * for which Duo MFA should _not_ be enforced. Users logging in from hosts
+     * contained in this list will be logged in without the MFA requirement.
+     * 
+     * @return
+     *     A list of IP addresses and subnets for which Duo MFA should not be
+     *     enforced.
+     * 
+     * @throws GuacamoleException 
+     *     If guacamole.properties cannot be parsed, or if an invalid IP address
+     *     or subnet is specified.
+     */
+    public List<IPAddress> getBypassHosts() throws GuacamoleException {
+        return environment.getProperty(DUO_BYPASS_HOSTS, Collections.emptyList());
+    }
+    
+    /**
+     * Returns the list of IP addresses and subnets defined in guacamole.properties
+     * for which Duo MFA should explicitly be enforced, while logins from all
+     * other hosts should not enforce MFA. Users logging in from hosts
+     * contained in this list will be required to complete the Duo MFA authentication,
+     * while users from all other hosts will be logged in without the MFA requirement.
+     * 
+     * @return
+     *     A list of IP addresses and subnets for which Duo MFA should be
+     *     explicitly enforced.
+     * 
+     * @throws GuacamoleException 
+     *     If guacamole.properties cannot be parsed, or if an invalid IP address
+     *     or subnet is specified.
+     */
+    public List<IPAddress> getEnforceHosts() throws GuacamoleException {
+        return environment.getProperty(DUO_ENFORCE_HOSTS, Collections.emptyList());
+    }
+    
+    
 
 }