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/*
* Copyright © 2017-2023 WireGuard LLC. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
package com.wireguard.android.util;
import android.content.Context;
import android.util.Log;
import com.wireguard.android.util.RootShell.RootShellException.Reason;
import com.wireguard.util.NonNullForAll;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.Collection;
import java.util.UUID;
import androidx.annotation.Nullable;
/**
* Helper class for running commands as root.
*/
@NonNullForAll
public class RootShell {
private static final String SU = "su";
private static final String TAG = "WireGuard/RootShell";
private final File localBinaryDir;
private final File localTemporaryDir;
private final Object lock = new Object();
private final String preamble;
@Nullable private Process process;
@Nullable private BufferedReader stderr;
@Nullable private OutputStreamWriter stdin;
@Nullable private BufferedReader stdout;
public RootShell(final Context context) {
localBinaryDir = new File(context.getCodeCacheDir(), "bin");
localTemporaryDir = new File(context.getCacheDir(), "tmp");
final String packageName = context.getPackageName();
if (packageName.contains("'"))
throw new RuntimeException("Impossibly invalid package name contains a single quote");
preamble = String.format("export CALLING_PACKAGE=%s PATH=\"%s:$PATH\" TMPDIR='%s'; magisk --sqlite \"UPDATE policies SET notification=0, logging=0 WHERE package_name='%s'\" >/dev/null 2>&1; id -u\n",
packageName, localBinaryDir, localTemporaryDir, packageName);
}
private static boolean isExecutableInPath(final String name) {
final String path = System.getenv("PATH");
if (path == null)
return false;
for (final String dir : path.split(":"))
if (new File(dir, name).canExecute())
return true;
return false;
}
private boolean isRunning() {
synchronized (lock) {
try {
// Throws an exception if the process hasn't finished yet.
if (process != null)
process.exitValue();
return false;
} catch (final IllegalThreadStateException ignored) {
// The existing process is still running.
return true;
}
}
}
/**
* Run a command in a root shell.
*
* @param output Lines read from stdout are appended to this list. Pass null if the
* output from the shell is not important.
* @param command Command to run as root.
* @return The exit value of the command.
*/
public int run(@Nullable final Collection<String> output, final String command)
throws IOException, RootShellException {
synchronized (lock) {
/* Start inside synchronized block to prevent a concurrent call to stop(). */
start();
final String marker = UUID.randomUUID().toString();
final String script = "echo " + marker + "; echo " + marker + " >&2; (" + command +
"); ret=$?; echo " + marker + " $ret; echo " + marker + " $ret >&2\n";
Log.v(TAG, "executing: " + command);
stdin.write(script);
stdin.flush();
String line;
int errnoStdout = Integer.MIN_VALUE;
int errnoStderr = Integer.MAX_VALUE;
int markersSeen = 0;
while ((line = stdout.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStdout = Integer.valueOf(line.substring(marker.length() + 1));
break;
}
} else if (markersSeen > 0) {
if (output != null)
output.add(line);
Log.v(TAG, "stdout: " + line);
}
}
while ((line = stderr.readLine()) != null) {
if (line.startsWith(marker)) {
++markersSeen;
if (line.length() > marker.length() + 1) {
errnoStderr = Integer.valueOf(line.substring(marker.length() + 1));
break;
}
} else if (markersSeen > 2) {
Log.v(TAG, "stderr: " + line);
}
}
if (markersSeen != 4)
throw new RootShellException(Reason.SHELL_MARKER_COUNT_ERROR, markersSeen);
if (errnoStdout != errnoStderr)
throw new RootShellException(Reason.SHELL_EXIT_STATUS_READ_ERROR);
Log.v(TAG, "exit: " + errnoStdout);
return errnoStdout;
}
}
public void start() throws IOException, RootShellException {
if (!isExecutableInPath(SU))
throw new RootShellException(Reason.NO_ROOT_ACCESS);
synchronized (lock) {
if (isRunning())
return;
if (!localBinaryDir.isDirectory() && !localBinaryDir.mkdirs())
throw new RootShellException(Reason.CREATE_BIN_DIR_ERROR);
if (!localTemporaryDir.isDirectory() && !localTemporaryDir.mkdirs())
throw new RootShellException(Reason.CREATE_TEMP_DIR_ERROR);
try {
final ProcessBuilder builder = new ProcessBuilder().command(SU);
builder.environment().put("LC_ALL", "C");
try {
process = builder.start();
} catch (final IOException e) {
// A failure at this stage means the device isn't rooted.
final RootShellException rse = new RootShellException(Reason.NO_ROOT_ACCESS);
rse.initCause(e);
throw rse;
}
stdin = new OutputStreamWriter(process.getOutputStream(), StandardCharsets.UTF_8);
stdout = new BufferedReader(new InputStreamReader(process.getInputStream(),
StandardCharsets.UTF_8));
stderr = new BufferedReader(new InputStreamReader(process.getErrorStream(),
StandardCharsets.UTF_8));
stdin.write(preamble);
stdin.flush();
// Check that the shell started successfully.
final String uid = stdout.readLine();
if (!"0".equals(uid)) {
Log.w(TAG, "Root check did not return correct UID: " + uid);
throw new RootShellException(Reason.NO_ROOT_ACCESS);
}
if (!isRunning()) {
String line;
while ((line = stderr.readLine()) != null) {
Log.w(TAG, "Root check returned an error: " + line);
if (line.contains("Permission denied"))
throw new RootShellException(Reason.NO_ROOT_ACCESS);
}
throw new RootShellException(Reason.SHELL_START_ERROR, process.exitValue());
}
} catch (final IOException | RootShellException e) {
stop();
throw e;
}
}
}
public void stop() {
synchronized (lock) {
if (process != null) {
process.destroy();
process = null;
}
}
}
public static class RootShellException extends Exception {
private final Object[] format;
private final Reason reason;
public RootShellException(final Reason reason, final Object... format) {
this.reason = reason;
this.format = format;
}
public Object[] getFormat() {
return format;
}
public Reason getReason() {
return reason;
}
public boolean isIORelated() {
return reason != Reason.NO_ROOT_ACCESS;
}
public enum Reason {
NO_ROOT_ACCESS,
SHELL_MARKER_COUNT_ERROR,
SHELL_EXIT_STATUS_READ_ERROR,
SHELL_START_ERROR,
CREATE_BIN_DIR_ERROR,
CREATE_TEMP_DIR_ERROR
}
}
}
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