// 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));
}
}
}
}