James Moger
2015-10-05 be49ef9b1b2ab0ee251085efd5930b6f99bbced9
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/*
 * Copyright 2014 gitblit.com.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.gitblit.transport.ssh;
 
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.InetSocketAddress;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.atomic.AtomicBoolean;
 
import org.apache.sshd.common.NamedFactory;
import org.apache.sshd.common.io.IoServiceFactoryFactory;
import org.apache.sshd.common.io.mina.MinaServiceFactoryFactory;
import org.apache.sshd.common.io.nio2.Nio2ServiceFactoryFactory;
import org.apache.sshd.common.util.SecurityUtils;
import org.apache.sshd.server.SshServer;
import org.apache.sshd.server.auth.CachingPublicKeyAuthenticator;
import org.apache.sshd.server.auth.UserAuth;
import org.apache.sshd.server.auth.UserAuthKeyboardInteractiveFactory;
import org.apache.sshd.server.auth.UserAuthPasswordFactory;
import org.apache.sshd.server.auth.UserAuthPublicKeyFactory;
import org.apache.sshd.server.auth.gss.GSSAuthenticator;
import org.apache.sshd.server.auth.gss.UserAuthGSSFactory;
import org.bouncycastle.openssl.PEMWriter;
import org.eclipse.jgit.internal.JGitText;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
import com.gitblit.Constants;
import com.gitblit.IStoredSettings;
import com.gitblit.Keys;
import com.gitblit.manager.IGitblit;
import com.gitblit.transport.ssh.commands.SshCommandFactory;
import com.gitblit.utils.JnaUtils;
import com.gitblit.utils.StringUtils;
import com.gitblit.utils.WorkQueue;
import com.google.common.io.Files;
 
/**
 * Manager for the ssh transport. Roughly analogous to the
 * {@link com.gitblit.transport.git.GitDaemon} class.
 *
 */
public class SshDaemon {
 
    private final Logger log = LoggerFactory.getLogger(SshDaemon.class);
 
    public static enum SshSessionBackend {
        MINA, NIO2
    }
 
    /**
     * 22: IANA assigned port number for ssh. Note that this is a distinct
     * concept from gitblit's default conf for ssh port -- this "default" is
     * what the git protocol itself defaults to if it sees and ssh url without a
     * port.
     */
    public static final int DEFAULT_PORT = 22;
 
    private final AtomicBoolean run;
 
    private final IGitblit gitblit;
    private final SshServer sshd;
 
    /**
     * Construct the Gitblit SSH daemon.
     *
     * @param gitblit
     * @param workQueue
     */
    public SshDaemon(IGitblit gitblit, WorkQueue workQueue) {
        this.gitblit = gitblit;
 
        IStoredSettings settings = gitblit.getSettings();
 
        // Ensure that Bouncy Castle is our JCE provider
        SecurityUtils.setRegisterBouncyCastle(true);
        if (SecurityUtils.isBouncyCastleRegistered()) {
            log.debug("BouncyCastle is registered as a JCE provider");
        }
 
        // Generate host RSA and DSA keypairs and create the host keypair provider
        File rsaKeyStore = new File(gitblit.getBaseFolder(), "ssh-rsa-hostkey.pem");
        File dsaKeyStore = new File(gitblit.getBaseFolder(), "ssh-dsa-hostkey.pem");
        generateKeyPair(rsaKeyStore, "RSA", 2048);
        generateKeyPair(dsaKeyStore, "DSA", 0);
        FileKeyPairProvider hostKeyPairProvider = new FileKeyPairProvider();
        hostKeyPairProvider.setFiles(new String [] { rsaKeyStore.getPath(), dsaKeyStore.getPath(), dsaKeyStore.getPath() });
 
        // Client public key authenticator
        SshKeyAuthenticator keyAuthenticator =
                new SshKeyAuthenticator(gitblit.getPublicKeyManager(), gitblit);
 
        // Configure the preferred SSHD backend
        String sshBackendStr = settings.getString(Keys.git.sshBackend,
                SshSessionBackend.NIO2.name());
        SshSessionBackend backend = SshSessionBackend.valueOf(sshBackendStr);
        System.setProperty(IoServiceFactoryFactory.class.getName(),
            backend == SshSessionBackend.MINA
                ? MinaServiceFactoryFactory.class.getName()
                : Nio2ServiceFactoryFactory.class.getName());
 
        // Create the socket address for binding the SSH server
        int port = settings.getInteger(Keys.git.sshPort, 0);
        String bindInterface = settings.getString(Keys.git.sshBindInterface, "");
        InetSocketAddress addr;
        if (StringUtils.isEmpty(bindInterface)) {
            addr = new InetSocketAddress(port);
        } else {
            addr = new InetSocketAddress(bindInterface, port);
        }
 
        //Will do GSS ?
        GSSAuthenticator gssAuthenticator = null;
        if(settings.getBoolean(Keys.git.sshWithKrb5, false)) {
            gssAuthenticator = new SshKrbAuthenticator(gitblit, settings);
            String keytabString = settings.getString(Keys.git.sshKrb5Keytab,
                    "");
            if(! keytabString.isEmpty()) {
                gssAuthenticator.setKeytabFile(keytabString);
            }
            String servicePrincipalName = settings.getString(Keys.git.sshKrb5ServicePrincipalName,
                    "");
            if(! servicePrincipalName.isEmpty()) {
                gssAuthenticator.setServicePrincipalName(servicePrincipalName);
            }
        }
 
        //Sort the authenticators for sshd
        List<NamedFactory<UserAuth>> userAuthFactories = new ArrayList<>();
        String sshAuthenticatorsOrderString = settings.getString(Keys.git.sshAuthenticatorsOrder,
                "password,keyboard-interactive,publickey");
        for(String authenticator: sshAuthenticatorsOrderString.split(",")) {
            String authenticatorName = authenticator.trim().toLowerCase(Locale.US);
            switch (authenticatorName) {
            case "gssapi-with-mic":
                if(gssAuthenticator != null) {
                    userAuthFactories.add(new UserAuthGSSFactory());
                }
                break;
            case "publickey":
                userAuthFactories.add(new UserAuthPublicKeyFactory());
                break;
            case "password":
                userAuthFactories.add(new UserAuthPasswordFactory());
                break;
            case "keyboard-interactive":
                userAuthFactories.add(new UserAuthKeyboardInteractiveFactory());
                break;
            default:
                log.error("Unknown ssh authenticator: '{}'", authenticatorName);
            }
        }
 
        // Create the SSH server
        sshd = SshServer.setUpDefaultServer();
        sshd.setPort(addr.getPort());
        sshd.setHost(addr.getHostName());
        sshd.setKeyPairProvider(hostKeyPairProvider);
        sshd.setPublickeyAuthenticator(new CachingPublicKeyAuthenticator(keyAuthenticator));
        sshd.setPasswordAuthenticator(new UsernamePasswordAuthenticator(gitblit));
        if(gssAuthenticator != null) {
            sshd.setGSSAuthenticator(gssAuthenticator);
        }
        sshd.setUserAuthFactories(userAuthFactories);
        sshd.setSessionFactory(new SshServerSessionFactory());
        sshd.setFileSystemFactory(new DisabledFilesystemFactory());
        sshd.setTcpipForwardingFilter(new NonForwardingFilter());
        sshd.setCommandFactory(new SshCommandFactory(gitblit, workQueue));
        sshd.setShellFactory(new WelcomeShell(settings));
 
        // Set the server id.  This can be queried with:
        //   ssh-keyscan -t rsa,dsa -p 29418 localhost
        String version = String.format("%s (%s-%s)", Constants.getGitBlitVersion().replace(' ', '_'),
                sshd.getVersion(), sshBackendStr);
        sshd.getProperties().put(SshServer.SERVER_IDENTIFICATION, version);
 
        run = new AtomicBoolean(false);
    }
 
    public String formatUrl(String gituser, String servername, String repository) {
        IStoredSettings settings = gitblit.getSettings();
 
        int port = sshd.getPort();
        int displayPort = settings.getInteger(Keys.git.sshAdvertisedPort, port);
        String displayServername = settings.getString(Keys.git.sshAdvertisedHost, "");
        if(displayServername.isEmpty()) {
            displayServername = servername;
        }
        if (displayPort == DEFAULT_PORT) {
            // standard port
            return MessageFormat.format("ssh://{0}@{1}/{2}", gituser, displayServername,
                    repository);
        } else {
            // non-standard port
            return MessageFormat.format("ssh://{0}@{1}:{2,number,0}/{3}",
                    gituser, displayServername, displayPort, repository);
        }
    }
 
    /**
     * Start this daemon on a background thread.
     *
     * @throws IOException
     *             the server socket could not be opened.
     * @throws IllegalStateException
     *             the daemon is already running.
     */
    public synchronized void start() throws IOException {
        if (run.get()) {
            throw new IllegalStateException(JGitText.get().daemonAlreadyRunning);
        }
 
        sshd.start();
        run.set(true);
 
        String sshBackendStr = gitblit.getSettings().getString(Keys.git.sshBackend,
                SshSessionBackend.NIO2.name());
 
        log.info(MessageFormat.format(
                "SSH Daemon ({0}) is listening on {1}:{2,number,0}",
                sshBackendStr, sshd.getHost(), sshd.getPort()));
    }
 
    /** @return true if this daemon is receiving connections. */
    public boolean isRunning() {
        return run.get();
    }
 
    /** Stop this daemon. */
    public synchronized void stop() {
        if (run.get()) {
            log.info("SSH Daemon stopping...");
            run.set(false);
 
            try {
                ((SshCommandFactory) sshd.getCommandFactory()).stop();
                sshd.stop();
            } catch (IOException e) {
                log.error("SSH Daemon stop interrupted", e);
            }
        }
    }
 
    private void generateKeyPair(File file, String algorithm, int keySize) {
        if (file.exists()) {
            return;
        }
        try {
            KeyPairGenerator generator = SecurityUtils.getKeyPairGenerator(algorithm);
            if (keySize != 0) {
                generator.initialize(keySize);
                log.info("Generating {}-{} SSH host keypair...", algorithm, keySize);
            } else {
                log.info("Generating {} SSH host keypair...", algorithm);
            }
            KeyPair kp = generator.generateKeyPair();
 
            // create an empty file and set the permissions
            Files.touch(file);
            try {
                JnaUtils.setFilemode(file, JnaUtils.S_IRUSR | JnaUtils.S_IWUSR);
            } catch (UnsatisfiedLinkError | UnsupportedOperationException e) {
                // Unexpected/Unsupported OS or Architecture
            }
 
            FileOutputStream os = new FileOutputStream(file);
            PEMWriter w = new PEMWriter(new OutputStreamWriter(os));
            w.writeObject(kp);
            w.flush();
            w.close();
        } catch (Exception e) {
            log.warn(MessageFormat.format("Unable to generate {0} keypair", algorithm), e);
            return;
        }
    }
}