com.google.gerrit.sshd.SuExec.java Source code

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Here is the source code for com.google.gerrit.sshd.SuExec.java

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// Copyright (C) 2010 The Android Open Source Project
//
// 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.google.gerrit.sshd;

import com.google.common.util.concurrent.Atomics;
import com.google.gerrit.reviewdb.client.Account;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.PeerDaemonUser;
import com.google.gerrit.sshd.SshScope.Context;
import com.google.inject.Inject;
import com.google.inject.Provider;

import org.apache.sshd.server.Command;
import org.apache.sshd.server.Environment;
import org.kohsuke.args4j.Argument;
import org.kohsuke.args4j.Option;

import java.io.IOException;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Executes any other command as a different user identity.
 * <p>
 * The calling user must be authenticated as a {@link PeerDaemonUser}, which
 * usually requires public key authentication using this daemon's private host
 * key, or a key on this daemon's peer host key ring.
 */
public final class SuExec extends BaseCommand {
    private final SshScope sshScope;
    private final DispatchCommandProvider dispatcher;

    private Provider<CurrentUser> caller;
    private Provider<SshSession> session;
    private IdentifiedUser.GenericFactory userFactory;
    private SshScope.Context callingContext;

    @Option(name = "--as", required = true)
    private Account.Id accountId;

    @Option(name = "--from")
    private SocketAddress peerAddress;

    @Argument(index = 0, multiValued = true, metaVar = "COMMAND")
    private List<String> args = new ArrayList<String>();

    private final AtomicReference<Command> atomicCmd;

    @Inject
    SuExec(final SshScope sshScope, @CommandName(Commands.ROOT) final DispatchCommandProvider dispatcher,
            final Provider<CurrentUser> caller, final Provider<SshSession> session,
            final IdentifiedUser.GenericFactory userFactory, final SshScope.Context callingContext) {
        this.sshScope = sshScope;
        this.dispatcher = dispatcher;
        this.caller = caller;
        this.session = session;
        this.userFactory = userFactory;
        this.callingContext = callingContext;
        atomicCmd = Atomics.newReference();
    }

    @Override
    public void start(Environment env) throws IOException {
        try {
            if (caller.get() instanceof PeerDaemonUser) {
                parseCommandLine();

                final Context ctx = callingContext.subContext(newSession(), join(args));
                final Context old = sshScope.set(ctx);
                try {
                    final BaseCommand cmd = dispatcher.get();
                    cmd.setArguments(args.toArray(new String[args.size()]));
                    provideStateTo(cmd);
                    atomicCmd.set(cmd);
                    cmd.start(env);
                } finally {
                    sshScope.set(old);
                }

            } else {
                throw new UnloggedFailure(1, "fatal: Not a peer daemon");
            }
        } catch (UnloggedFailure e) {
            String msg = e.getMessage();
            if (!msg.endsWith("\n")) {
                msg += "\n";
            }
            err.write(msg.getBytes("UTF-8"));
            err.flush();
            onExit(1);
        }
    }

    private SshSession newSession() {
        final SocketAddress peer;
        if (peerAddress == null) {
            peer = session.get().getRemoteAddress();
        } else {
            peer = peerAddress;
        }
        return new SshSession(session.get(), peer, userFactory.create(peer, accountId));
    }

    private static String join(List<String> args) {
        StringBuilder r = new StringBuilder();
        for (String a : args) {
            if (r.length() > 0) {
                r.append(" ");
            }
            r.append(a);
        }
        return r.toString();
    }

    @Override
    public void destroy() {
        Command cmd = atomicCmd.getAndSet(null);
        if (cmd != null) {
            cmd.destroy();
        }
    }
}