diff options
Diffstat (limited to 'src/main/java/com/google/devtools/build/lib/sandbox')
3 files changed, 391 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/BUILD b/src/main/java/com/google/devtools/build/lib/sandbox/BUILD index 9d849a8fc1..daaf92a5e7 100644 --- a/src/main/java/com/google/devtools/build/lib/sandbox/BUILD +++ b/src/main/java/com/google/devtools/build/lib/sandbox/BUILD @@ -30,6 +30,8 @@ java_library( "//src/main/java/com/google/devtools/build/lib/standalone", "//src/main/java/com/google/devtools/build/lib/vfs", "//src/main/java/com/google/devtools/common/options", + "//third_party:auto_value", "//third_party:guava", + "//third_party:jsr305", ], ) diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/RealSandboxfsProcess.java b/src/main/java/com/google/devtools/build/lib/sandbox/RealSandboxfsProcess.java new file mode 100644 index 0000000000..70a355f378 --- /dev/null +++ b/src/main/java/com/google/devtools/build/lib/sandbox/RealSandboxfsProcess.java @@ -0,0 +1,261 @@ +// Copyright 2018 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 static com.google.common.base.Preconditions.checkNotNull; +import static java.nio.charset.StandardCharsets.UTF_8; + +import com.google.common.collect.ImmutableList; +import com.google.common.collect.ImmutableMap; +import com.google.devtools.build.lib.shell.Subprocess; +import com.google.devtools.build.lib.shell.SubprocessBuilder; +import com.google.devtools.build.lib.util.OS; +import com.google.devtools.build.lib.vfs.Path; +import com.google.devtools.build.lib.vfs.PathFragment; +import java.io.BufferedReader; +import java.io.BufferedWriter; +import java.io.IOException; +import java.io.InputStreamReader; +import java.io.OutputStreamWriter; +import java.util.List; +import java.util.function.Function; +import java.util.logging.Logger; +import java.util.stream.Collectors; +import javax.annotation.Nullable; + +/** A sandboxfs implementation that uses an external sandboxfs binary to manage the mount point. */ +final class RealSandboxfsProcess implements SandboxfsProcess { + private static final Logger log = Logger.getLogger(RealSandboxfsProcess.class.getName()); + + /** Directory on which the sandboxfs is serving. */ + private final Path mountPoint; + + /** + * Process handle to the sandboxfs instance. Null only after {@link #destroy()} has been invoked. + */ + private @Nullable Subprocess process; + + /** + * Writer with which to send data to the sandboxfs instance. Null only after {@link #destroy()} + * has been invoked. + */ + private @Nullable BufferedWriter processStdIn; + + /** + * Reader with which to receive data from the sandboxfs instance. Null only after + * {@link #destroy()} has been invoked. + */ + private @Nullable BufferedReader processStdOut; + + /** + * Shutdown hook to stop the sandboxfs instance on abrupt termination. Null only after + * {@link #destroy()} has been invoked. + */ + private @Nullable Thread shutdownHook; + + /** + * Initializes a new sandboxfs process instance. + * + * @param process process handle for the already-running sandboxfs instance + */ + private RealSandboxfsProcess(Path mountPoint, Subprocess process) { + this.mountPoint = mountPoint; + + this.process = process; + this.processStdIn = new BufferedWriter( + new OutputStreamWriter(process.getOutputStream(), UTF_8)); + this.processStdOut = new BufferedReader( + new InputStreamReader(process.getInputStream(), UTF_8)); + + this.shutdownHook = + new Thread( + () -> { + try { + this.destroy(); + } catch (Exception e) { + log.warning("Failed to destroy running sandboxfs instance; mount point may have " + + "been left behind: " + e); + } + }); + Runtime.getRuntime().addShutdownHook(shutdownHook); + } + + /** + * Mounts a new sandboxfs instance. + * + * <p>The root of the file system instance is left unmapped which means that it remains as + * read-only throughout the lifetime of this instance. Writable subdirectories can later be + * mapped via {@link #map(List)}. + * + * @param binary path to the sandboxfs binary + * @param mountPoint directory on which to mount the sandboxfs instance + * @param logFile path to the file that will receive all sandboxfs logging output + * @return a new handle that represents the running process + * @throws IOException if there is a problem starting the process + */ + static SandboxfsProcess mount(Path binary, Path mountPoint, Path logFile) throws IOException { + log.info("Mounting sandboxfs (" + binary + ") onto " + mountPoint); + + // TODO(jmmv): Before starting a sandboxfs serving instance, we must query the current version + // of sandboxfs and check if we support its communication protocol. + + ImmutableList.Builder<String> argvBuilder = ImmutableList.builder(); + + argvBuilder.add(binary.getPathString()); + + // On macOS, we need to allow users other than self to access the sandboxfs instance. This is + // necessary because macOS's amfid, which runs as root, has to have access to the binaries + // within the sandbox in order to validate signatures. See: + // http://julio.meroh.net/2017/10/fighting-execs-sandboxfs-macos.html + argvBuilder.add(OS.getCurrent() == OS.DARWIN ? "--allow=other" : "--allow=self"); + + // TODO(jmmv): Pass flags to enable sandboxfs' debugging support (--listen_address and --debug) + // when requested by the user via --sandbox_debug. Tricky because we have to figure out how to + // deal with port numbers (which sandboxfs can autoassign, but doesn't currently promise a way + // to tell us back what it picked). + + argvBuilder.add(mountPoint.getPathString()); + + SubprocessBuilder processBuilder = new SubprocessBuilder(); + processBuilder.setArgv(argvBuilder.build()); + processBuilder.setStderr(logFile.getPathFile()); + processBuilder.setEnv(ImmutableMap.of( + // sandboxfs may need to locate fusermount depending on the FUSE implementation so pass the + // PATH to the subprocess (which we assume is sufficient). + "PATH", System.getenv("PATH"))); + + Subprocess process = processBuilder.start(); + RealSandboxfsProcess sandboxfs = new RealSandboxfsProcess(mountPoint, process); + // TODO(jmmv): We should have a better mechanism to wait for sandboxfs to start successfully but + // sandboxfs currently provides no interface to do so. Just try to push an empty configuration + // and see if it works. + try { + sandboxfs.reconfigure("[]\n\n"); + } catch (IOException e) { + destroyProcess(process); + throw new IOException("sandboxfs failed to start", e); + } + return sandboxfs; + } + + @Override + public Path getMountPoint() { + return mountPoint; + } + + @Override + public boolean isAlive() { + return process != null && !process.finished(); + } + + /** + * Destroys a process and waits for it to exit. + * + * @param process the process to destroy. + */ + // TODO(jmmv): This is adapted from Worker.java. Should probably replace both with a new variant + // of Uninterruptibles.callUninterruptibly that takes a lambda instead of a callable. + private static void destroyProcess(Subprocess process) { + process.destroy(); + + boolean interrupted = false; + try { + while (true) { + try { + process.waitFor(); + return; + } catch (InterruptedException ie) { + interrupted = true; + } + } + } finally { + if (interrupted) { + Thread.currentThread().interrupt(); + } + } + } + + @Override + public synchronized void destroy() { + if (shutdownHook != null) { + Runtime.getRuntime().removeShutdownHook(shutdownHook); + shutdownHook = null; + } + + if (processStdIn != null) { + try { + processStdIn.close(); + } catch (IOException e) { + log.warning("Failed to close sandboxfs's stdin pipe: " + e); + } + processStdIn = null; + } + + if (processStdOut != null) { + try { + processStdOut.close(); + } catch (IOException e) { + log.warning("Failed to close sandboxfs's stdout pipe: " + e); + } + processStdOut = null; + } + + if (process != null) { + destroyProcess(process); + process = null; + } + } + + /** + * Pushes a new configuration to sandboxfs and waits for acceptance. + * + * @param config the configuration chunk to push to sandboxfs + * @throws IOException if sandboxfs cannot be reconfigured either because of an error in the + * configuration or because we failed to communicate with the subprocess + */ + private synchronized void reconfigure(String config) throws IOException { + checkNotNull(processStdIn, "sandboxfs already has been destroyed"); + processStdIn.write(config); + processStdIn.flush(); + + checkNotNull(processStdOut, "sandboxfs has already been destroyed"); + String done = processStdOut.readLine(); + if (done == null) { + throw new IOException("premature end of output from sandboxfs"); + } + if (!done.equals("Done")) { + throw new IOException("received unknown string from sandboxfs: " + done + "; expected Done"); + } + } + + @Override + public void map(List<Mapping> mappings) throws IOException { + Function<Mapping, String> formatMapping = + (mapping) -> String.format( + "{\"Map\": {\"Mapping\": \"%s\", \"Target\": \"%s\", \"Writable\": %s}}", + mapping.path(), mapping.target(), mapping.writable() ? "true" : "false"); + + StringBuilder sb = new StringBuilder(); + sb.append("[\n"); + sb.append(mappings.stream().map(formatMapping).collect(Collectors.joining(",\n"))); + sb.append("]\n\n"); + reconfigure(sb.toString()); + } + + @Override + public void unmap(PathFragment mapping) throws IOException { + reconfigure(String.format("[{\"Unmap\": \"%s\"}]\n\n", mapping)); + } +} diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxfsProcess.java b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxfsProcess.java new file mode 100644 index 0000000000..4b56ed3265 --- /dev/null +++ b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxfsProcess.java @@ -0,0 +1,128 @@ +// Copyright 2018 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 static com.google.common.base.Preconditions.checkState; + +import com.google.auto.value.AutoValue; +import com.google.devtools.build.lib.vfs.Path; +import com.google.devtools.build.lib.vfs.PathFragment; +import java.io.IOException; +import java.util.List; + +/** Interface to interact with a sandboxfs instance. */ +interface SandboxfsProcess { + + /** Represents a single mapping within a sandboxfs file system. */ + @AutoValue + abstract class Mapping { + /** + * Path within the sandbox. This looks like an absolute path but is treated as relative to the + * sandbox's root. + */ + abstract PathFragment path(); + + /** Absolute path from the host's file system to map into the sandbox. */ + abstract PathFragment target(); + + /** Whether the mapped path is writable or not. */ + abstract boolean writable(); + + /** Constructs a new mapping builder. */ + static Builder builder() { + return new AutoValue_SandboxfsProcess_Mapping.Builder(); + } + + /** Builder for a single mapping within a sandboxfs file system. */ + @AutoValue.Builder + abstract static class Builder { + /** + * Sets the path within the sandbox on which this mapping will appear. This looks like an + * absolute path but is treated as relative to the sandbox's root. + * + * @param path absolute path rooted at the sandbox's mount point + * @return the builder instance + */ + abstract Builder setPath(PathFragment path); + + /** + * Sets the path to which this mapping refers. This is an absolute path into the host's + * file system. + * + * @param target absolute path into the host's file system + * @return the builder instance + */ + abstract Builder setTarget(PathFragment target); + + /** + * Sets whether this mapping is writable or not when accessed via the sandbox. + * + * @param writable whether the mapping is writable or not + * @return the builder instance + */ + abstract Builder setWritable(boolean writable); + + abstract Mapping autoBuild(); + + /** + * Constructs the mapping and validates field invariants. + * + * @return the constructed mapping. + */ + public Mapping build() { + Mapping mapping = autoBuild(); + checkState(mapping.path().isAbsolute(), "Mapping specifications are supposed to be " + + "absolute but %s is not", mapping.path()); + checkState(mapping.target().isAbsolute(), "Mapping targets are supposed to be " + + "absolute but %s is not", mapping.target()); + return mapping; + } + } + } + + /** Returns the path to the sandboxfs's mount point. */ + Path getMountPoint(); + + /** Returns true if the sandboxfs process is still alive. */ + boolean isAlive(); + + /** + * Unmounts and stops the sandboxfs process. + * + * <p>This function must be idempotent because there can be a race between explicit calls during + * regular execution and calls from shutdown hooks. + */ + void destroy(); + + /** + * Adds new mappings to the sandboxfs instance. + * + * @param mappings the collection of mappings to add, which must not have yet been previously + * mapped + * @throws IOException if sandboxfs cannot be reconfigured either because of an error in the + * configuration or because we failed to communicate with the subprocess + */ + void map(List<Mapping> mappings) throws IOException; + + /** + * Removes a mapping from the sandboxfs instance. + * + * @param mapping the mapping to remove, which must have been previously mapped. This looks like + * an absolute path but is treated as relative to the sandbox's root. + * @throws IOException if sandboxfs cannot be reconfigured either because of an error in the + * configuration or because we failed to communicate with the subprocess + */ + void unmap(PathFragment mapping) throws IOException; +} |