Implemented access control for SFTP

pom.xml

@@ -53,6 +53,12 @@
             <version>2.3.0</version>
         </dependency>
 
+        <dependency>
+            <groupId>org.apache.sshd</groupId>
+            <artifactId>sshd-contrib</artifactId>
+            <version>2.3.0</version>
+        </dependency>
+
         <dependency>
             <groupId>org.apache.sshd</groupId>
             <artifactId>sshd-common</artifactId>

src/main/java/com/ryanmichela/sshd/ConfigPasswordAuthenticator.java

@@ -20,7 +20,7 @@ public class ConfigPasswordAuthenticator implements PasswordAuthenticator {
 	{
 		// Depending on our hash type, we have to try and figure out what we're doing.
 		String HashType = SshdPlugin.instance.getConfig().getString("PasswordType");
-		String ConfigHash = SshdPlugin.instance.getConfig().getString("Credentials." + username.trim());
+		String ConfigHash = SshdPlugin.instance.getConfig().getString("Credentials." + username.trim() + ".password");
 
 		if (ConfigHash == null)
 			SshdPlugin.instance.getLogger().warning("Config has no such user: " + username);

src/main/java/com/ryanmichela/sshd/SshdPlugin.java

@@ -1,9 +1,13 @@
 package com.ryanmichela.sshd;
 
 import org.apache.sshd.common.file.virtualfs.VirtualFileSystemFactory;
+import org.apache.sshd.common.session.helpers.AbstractSession;
 import org.apache.sshd.server.SshServer;
 import org.apache.sshd.server.keyprovider.SimpleGeneratorHostKeyProvider;
+import org.apache.sshd.server.session.ServerSession;
 import org.apache.sshd.server.subsystem.sftp.SftpSubsystemFactory;
+import org.apache.sshd.server.subsystem.sftp.SimpleAccessControlSftpEventListener;
+import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.plugin.java.JavaPlugin;
 
 import com.ryanmichela.sshd.ConsoleShellFactory;
@@ -14,18 +18,35 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Collections;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Map;
 import java.util.logging.Level;
+import java.util.stream.Stream;
 
 /**
  * Copyright 2013 Ryan Michela
  */
-public
-class SshdPlugin extends JavaPlugin
+public class SshdPlugin extends JavaPlugin
 {
+	private SshServer sshd;
+	public static SshdPlugin instance;
 
-  private SshServer sshd;
-  public static SshdPlugin instance;
+	public static List<ConfigurationSection> GetSections(ConfigurationSection source) 
+	{
+		if (source == null)
+			return null;
+
+		List<ConfigurationSection> nodes = new ArrayList<ConfigurationSection>();
+		for (String key : source.getKeys(false)) 
+		{
+			if (source.isConfigurationSection(key)) 
+				nodes.add(source.getConfigurationSection(key));
+		}
+		return nodes;
+	}
 
 	@Override public void onLoad()
 	{
@@ -73,9 +94,90 @@ class SshdPlugin extends JavaPlugin
 
 		if (getConfig().getBoolean("EnableSFTP"))
 		{
-			sshd.setSubsystemFactories(Collections.singletonList(new SftpSubsystemFactory()));
-			sshd.setFileSystemFactory(
-				new VirtualFileSystemFactory(FileSystems.getDefault().getPath(getDataFolder().getAbsolutePath()).getParent().getParent()));
+			// Handle access control for SFTP.
+			SftpSubsystemFactory.Builder builder = new SftpSubsystemFactory.Builder();
+			builder.addSftpEventListener(new SimpleAccessControlSftpEventListener() {
+				protected boolean isAccessAllowed(ServerSession session, String remote, Path localpath)
+				{
+					try
+					{
+						ConfigurationSection UsernameNamespace = getConfig().getConfigurationSection("Credentials." + session.getUsername() + ".sftp");
+
+						// They don't have SFTP enabled so deny them.
+						if (UsernameNamespace == null || !UsernameNamespace.getBoolean("enabled"))
+							return false;
+
+						
+						List<ConfigurationSection> rules = GetSections(UsernameNamespace.getConfigurationSection("rules"));
+						if (rules != null)
+						{
+							for (ConfigurationSection path : rules)
+							{
+								// Check if the requesting path matches
+								if (localpath.toString().matches(path.getName()))
+								{
+									// Check if they have read permissions
+									if (path.getBoolean("readable"))
+										return true;
+
+									getLogger().info(String.format("Denied %s read access to \"%s\" matching rule \"%s\"", session.getUsername(), localpath.toString(), path.getName()));
+									return false;
+								}
+							}
+						}
+
+						return UsernameNamespace.getString("default").equalsIgnoreCase("allow");
+					}
+					catch (Exception e)
+					{
+						e.printStackTrace();
+						// Automatically deny.
+						return false;
+					}
+				}
+
+				protected boolean isModificationAllowed(ServerSession session, String remote, Path localpath)
+				{
+					try
+					{
+						ConfigurationSection UsernameNamespace = getConfig().getConfigurationSection("Credentials." + session.getUsername() + ".sftp");
+
+						// They don't have SFTP enabled so deny them.
+						if (UsernameNamespace == null || !UsernameNamespace.getBoolean("enabled"))
+							return false;
+
+						// Check a list of files against a path trying to be accessed.
+						List<ConfigurationSection> rules = GetSections(UsernameNamespace.getConfigurationSection("rules"));
+						if (rules != null)
+						{
+							for (ConfigurationSection path : rules)
+							{
+								// Check if the requesting path matches
+								if (localpath.toString().matches(path.getName()))
+								{
+									// Check if they have read permissions
+									if (path.getBoolean("writeable"))
+										return true;
+
+									getLogger().info(String.format("Denied %s modifications to \"%s\" matching rule \"%s\"", session.getUsername(), localpath.toString(), path.getName()));
+									return false;
+								}
+							}
+						}
+
+						return UsernameNamespace.getString("default").equalsIgnoreCase("allow");
+					}
+					catch (Exception e)
+					{
+						e.printStackTrace();
+						// Automatically deny.
+						return false;
+					}
+				}
+			});
+
+			sshd.setSubsystemFactories(Collections.singletonList(builder.build()));
+			sshd.setFileSystemFactory(new VirtualFileSystemFactory(FileSystems.getDefault().getPath(getDataFolder().getAbsolutePath()).getParent().getParent()));
 		}
 
 		this.getCommand("mkpasswd").setExecutor(new MkpasswdCommand());
@@ -95,11 +197,16 @@ class SshdPlugin extends JavaPlugin
 	{
 		try
 		{
-			sshd.stop();
+			// Terminate any active sessions
+			for (AbstractSession as : sshd.getActiveSessions())
+				as.close(true);
+			// Pass "true" to stop immediately!
+			sshd.stop(true);
 		}
 		catch (Exception e)
 		{
 			// do nothing
+			e.printStackTrace();
 		}
 	}
 }

src/main/resources/config.yml

@@ -37,5 +37,34 @@ PasswordType: bcrypt
 
 # Associate each username with a password hash (or the password if the PasswordType is set to PLAIN)
 Credentials:
-#    user1: password1
-#    user2: password2
+     # Username (should match SSH key if using key-based authentication)
+     justasic:
+        # Password hash from /mkpasswd command
+        password: $2a$10$Oqk83FrypRrMF35EDeoQDuidJOQEWBE0joEQ7MJFi/Oeg26wQ3fm2
+        # Whether they can read, write, or have read/write permissions to console.
+        console: RW
+        # SFTP access for this user.
+        sftp:
+          # Whether SFTP is enabled for this user.
+          enabled: true
+          # Whether to deny by default or allow by default
+          default: allow
+          # Rules regarding their SFTP access.
+          # These rules are relative to the server root.
+          # This acts as a chroot for the server root.
+          # Each path can be an absolute path or a regular expression.
+          rules:
+            "/path/to/file":
+                # Whether the user can read the file over SFTP
+                readable: true
+                # Whether the user can write/modify the file over SFTP
+                writeable: true
+            "/path/to/regex/*":
+                readable: true
+                writeable: false
+            "/path/to/directory/":
+                readable: false
+                writeable: true
+            "/another/example/path":
+                readable: false
+                writeable: false