// Copyright 2014 The Bazel Authors. All rights reserved. // // 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.devtools.build.lib.sandbox; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Maps; import com.google.devtools.build.lib.actions.ActionExecutionContext; import com.google.devtools.build.lib.actions.ActionStatusMessage; import com.google.devtools.build.lib.actions.ExecException; import com.google.devtools.build.lib.actions.ExecutionStrategy; import com.google.devtools.build.lib.actions.Executor; import com.google.devtools.build.lib.actions.Spawn; import com.google.devtools.build.lib.actions.SpawnActionContext; import com.google.devtools.build.lib.actions.UserExecException; import com.google.devtools.build.lib.analysis.BlazeDirectories; import com.google.devtools.build.lib.buildtool.BuildRequest; import com.google.devtools.build.lib.exec.SpawnInputExpander; import com.google.devtools.build.lib.runtime.CommandEnvironment; import com.google.devtools.build.lib.vfs.FileSystem; import com.google.devtools.build.lib.vfs.FileSystemUtils; import com.google.devtools.build.lib.vfs.Path; import com.google.devtools.build.lib.vfs.PathFragment; import com.google.devtools.build.lib.vfs.Symlinks; import java.io.IOException; import java.util.Map; import java.util.Set; import java.util.SortedMap; import java.util.concurrent.atomic.AtomicReference; /** Strategy that uses sandboxing to execute a process. */ @ExecutionStrategy( name = {"sandboxed", "linux-sandbox"}, contextType = SpawnActionContext.class ) public class LinuxSandboxedStrategy extends SandboxStrategy { public static boolean isSupported(CommandEnvironment cmdEnv) { return LinuxSandboxRunner.isSupported(cmdEnv); } private final SandboxOptions sandboxOptions; private final BlazeDirectories blazeDirs; private final Path execRoot; private final boolean verboseFailures; private final SpawnInputExpander spawnInputExpander; private final Path inaccessibleHelperFile; private final Path inaccessibleHelperDir; private LinuxSandboxedStrategy( CommandEnvironment cmdEnv, BuildRequest buildRequest, Path sandboxBase, boolean verboseFailures, Path inaccessibleHelperFile, Path inaccessibleHelperDir) { super( cmdEnv, buildRequest, sandboxBase, verboseFailures, buildRequest.getOptions(SandboxOptions.class)); this.sandboxOptions = buildRequest.getOptions(SandboxOptions.class); this.blazeDirs = cmdEnv.getDirectories(); this.execRoot = blazeDirs.getExecRoot(); this.verboseFailures = verboseFailures; this.spawnInputExpander = new SpawnInputExpander(false); this.inaccessibleHelperFile = inaccessibleHelperFile; this.inaccessibleHelperDir = inaccessibleHelperDir; } static LinuxSandboxedStrategy create( CommandEnvironment cmdEnv, BuildRequest buildRequest, Path sandboxBase, boolean verboseFailures) throws IOException { Path inaccessibleHelperFile = sandboxBase.getRelative("inaccessibleHelperFile"); FileSystemUtils.touchFile(inaccessibleHelperFile); inaccessibleHelperFile.setReadable(false); inaccessibleHelperFile.setWritable(false); inaccessibleHelperFile.setExecutable(false); Path inaccessibleHelperDir = sandboxBase.getRelative("inaccessibleHelperDir"); inaccessibleHelperDir.createDirectory(); inaccessibleHelperDir.setReadable(false); inaccessibleHelperDir.setWritable(false); inaccessibleHelperDir.setExecutable(false); return new LinuxSandboxedStrategy( cmdEnv, buildRequest, sandboxBase, verboseFailures, inaccessibleHelperFile, inaccessibleHelperDir); } @Override protected void actuallyExec( Spawn spawn, ActionExecutionContext actionExecutionContext, AtomicReference<Class<? extends SpawnActionContext>> writeOutputFiles) throws IOException, ExecException, InterruptedException { Executor executor = actionExecutionContext.getExecutor(); executor .getEventBus() .post(ActionStatusMessage.runningStrategy(spawn.getResourceOwner(), "linux-sandbox")); SandboxHelpers.reportSubcommand(executor, spawn); // Each invocation of "exec" gets its own sandbox. Path sandboxPath = getSandboxRoot(); Path sandboxExecRoot = sandboxPath.getRelative("execroot").getRelative(execRoot.getBaseName()); Set<Path> writableDirs = getWritableDirs(sandboxExecRoot, spawn.getEnvironment()); SymlinkedExecRoot symlinkedExecRoot = new SymlinkedExecRoot(sandboxExecRoot); ImmutableSet<PathFragment> outputs = SandboxHelpers.getOutputFiles(spawn); symlinkedExecRoot.createFileSystem( SandboxHelpers.getInputFiles(spawnInputExpander, execRoot, spawn, actionExecutionContext), outputs, writableDirs); SandboxRunner runner = new LinuxSandboxRunner( sandboxExecRoot, writableDirs, getTmpfsPaths(), getReadOnlyBindMounts(blazeDirs, sandboxExecRoot), verboseFailures, sandboxOptions.sandboxDebug); try { runSpawn( spawn, actionExecutionContext, spawn.getEnvironment(), symlinkedExecRoot, outputs, runner, writeOutputFiles); } finally { if (!sandboxOptions.sandboxDebug) { try { FileSystemUtils.deleteTree(sandboxPath); } catch (IOException e) { // This usually means that the Spawn itself exited, but still has children running that // we couldn't wait for, which now block deletion of the sandbox directory. On Linux this // should never happen, as we use PID namespaces and where they are not available the // subreaper feature to make sure all children have been reliably killed before returning, // but on other OS this might not always work. The SandboxModule will try to delete them // again when the build is all done, at which point it hopefully works, so let's just go // on here. } } } } @Override protected ImmutableSet<Path> getWritableDirs(Path sandboxExecRoot, Map<String, String> env) throws IOException { ImmutableSet.Builder<Path> writableDirs = ImmutableSet.builder(); writableDirs.addAll(super.getWritableDirs(sandboxExecRoot, env)); FileSystem fs = sandboxExecRoot.getFileSystem(); writableDirs.add(fs.getPath("/dev/shm").resolveSymbolicLinks()); writableDirs.add(fs.getPath("/tmp")); return writableDirs.build(); } private ImmutableSet<Path> getTmpfsPaths() { ImmutableSet.Builder<Path> tmpfsPaths = ImmutableSet.builder(); for (String tmpfsPath : sandboxOptions.sandboxTmpfsPath) { tmpfsPaths.add(blazeDirs.getFileSystem().getPath(tmpfsPath)); } return tmpfsPaths.build(); } private SortedMap<Path, Path> getReadOnlyBindMounts( BlazeDirectories blazeDirs, Path sandboxExecRoot) throws UserExecException { Path tmpPath = blazeDirs.getFileSystem().getPath("/tmp"); final SortedMap<Path, Path> bindMounts = Maps.newTreeMap(); if (blazeDirs.getWorkspace().startsWith(tmpPath)) { bindMounts.put(blazeDirs.getWorkspace(), blazeDirs.getWorkspace()); } if (blazeDirs.getOutputBase().startsWith(tmpPath)) { bindMounts.put(blazeDirs.getOutputBase(), blazeDirs.getOutputBase()); } for (ImmutableMap.Entry<String, String> additionalMountPath : sandboxOptions.sandboxAdditionalMounts) { try { final Path mountTarget = blazeDirs.getFileSystem().getPath(additionalMountPath.getValue()); // If source path is relative, treat it as a relative path inside the execution root final Path mountSource = sandboxExecRoot.getRelative(additionalMountPath.getKey()); // If a target has more than one source path, the latter one will take effect. bindMounts.put(mountTarget, mountSource); } catch (IllegalArgumentException e) { throw new UserExecException( String.format("Error occurred when analyzing bind mount pairs. %s", e.getMessage())); } } for (Path inaccessiblePath : getInaccessiblePaths()) { if (inaccessiblePath.isDirectory(Symlinks.NOFOLLOW)) { bindMounts.put(inaccessiblePath, inaccessibleHelperDir); } else { bindMounts.put(inaccessiblePath, inaccessibleHelperFile); } } validateBindMounts(bindMounts); return bindMounts; } /** * This method does the following things: - If mount source does not exist on the host system, * throw an error message - If mount target exists, check whether the source and target are of the * same type - If mount target does not exist on the host system, throw an error message * * @param bindMounts the bind mounts map with target as key and source as value * @throws UserExecException */ private void validateBindMounts(SortedMap<Path, Path> bindMounts) throws UserExecException { for (SortedMap.Entry<Path, Path> bindMount : bindMounts.entrySet()) { final Path source = bindMount.getValue(); final Path target = bindMount.getKey(); // Mount source should exist in the file system if (!source.exists()) { throw new UserExecException(String.format("Mount source '%s' does not exist.", source)); } // If target exists, but is not of the same type as the source, then we cannot mount it. if (target.exists()) { boolean areBothDirectories = source.isDirectory() && target.isDirectory(); boolean isSourceFile = source.isFile() || source.isSymbolicLink(); boolean isTargetFile = target.isFile() || target.isSymbolicLink(); boolean areBothFiles = isSourceFile && isTargetFile; if (!(areBothDirectories || areBothFiles)) { // Source and target are not of the same type; we cannot mount it. throw new UserExecException( String.format( "Mount target '%s' is not of the same type as mount source '%s'.", target, source)); } } else { // Mount target should exist in the file system throw new UserExecException( String.format( "Mount target '%s' does not exist. Bazel only supports bind mounting on top of " + "existing files/directories. Please create an empty file or directory at " + "the mount target path according to the type of mount source.", target)); } } } }