blob: 476328711e67edb6caa561186a735f3c19228ad3 [file] [log] [blame]
/*
* 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 android.tests.getinfo;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.regex.Pattern;
/** Crawls /proc to find processes that are running as root. */
class RootProcessScanner {
/** Processes that are allowed to run as root. */
private static final Pattern ROOT_PROCESS_WHITELIST_PATTERN = getRootProcessWhitelistPattern(
"debuggerd",
"init",
"installd",
"servicemanager",
"vold",
"zygote"
);
/** Combine the individual patterns into one super pattern. */
private static Pattern getRootProcessWhitelistPattern(String... patterns) {
StringBuilder rootProcessPattern = new StringBuilder();
for (int i = 0; i < patterns.length; i++) {
rootProcessPattern.append(patterns[i]);
if (i + 1 < patterns.length) {
rootProcessPattern.append('|');
}
}
return Pattern.compile(rootProcessPattern.toString());
}
/** Test that there are no unapproved root processes running on the system. */
public static String[] getRootProcesses()
throws FileNotFoundException, MalformedStatMException {
List<File> rootProcessDirs = getRootProcessDirs();
String[] rootProcessNames = new String[rootProcessDirs.size()];
for (int i = 0; i < rootProcessNames.length; i++) {
rootProcessNames[i] = getProcessName(rootProcessDirs.get(i));
}
return rootProcessNames;
}
private static List<File> getRootProcessDirs()
throws FileNotFoundException, MalformedStatMException {
File proc = new File("/proc");
if (!proc.exists()) {
throw new FileNotFoundException(proc + " is missing (man 5 proc)");
}
List<File> rootProcesses = new ArrayList<File>();
File[] processDirs = proc.listFiles();
if (processDirs != null && processDirs.length > 0) {
for (File processDir : processDirs) {
if (isUnapprovedRootProcess(processDir)) {
rootProcesses.add(processDir);
}
}
}
return rootProcesses;
}
/**
* Filters out processes in /proc that are not approved.
* @throws FileNotFoundException
* @throws MalformedStatMException
*/
private static boolean isUnapprovedRootProcess(File pathname)
throws FileNotFoundException, MalformedStatMException {
return isPidDirectory(pathname)
&& !isKernelProcess(pathname)
&& isRootProcess(pathname);
}
private static boolean isPidDirectory(File pathname) {
return pathname.isDirectory() && Pattern.matches("\\d+", pathname.getName());
}
private static boolean isKernelProcess(File processDir)
throws FileNotFoundException, MalformedStatMException {
File statm = getProcessStatM(processDir);
Scanner scanner = null;
try {
scanner = new Scanner(statm);
boolean allZero = true;
for (int i = 0; i < 7; i++) {
if (scanner.nextInt() != 0) {
allZero = false;
}
}
if (scanner.hasNext()) {
throw new MalformedStatMException(processDir
+ " statm expected to have 7 integers (man 5 proc)");
}
return allZero;
} finally {
if (scanner != null) {
scanner.close();
}
}
}
private static File getProcessStatM(File processDir) {
return new File(processDir, "statm");
}
public static class MalformedStatMException extends Exception {
MalformedStatMException(String detailMessage) {
super(detailMessage);
}
}
/**
* Return whether or not this process is running as root without being approved.
*
* @param processDir with the status file
* @return whether or not it is a unwhitelisted root process
* @throws FileNotFoundException
*/
private static boolean isRootProcess(File processDir) throws FileNotFoundException {
File status = getProcessStatus(processDir);
Scanner scanner = null;
try {
scanner = new Scanner(status);
scanner = findToken(scanner, "Name:");
String name = scanner.next();
scanner = findToken(scanner, "Uid:");
boolean rootUid = hasRootId(scanner);
scanner = findToken(scanner, "Gid:");
boolean rootGid = hasRootId(scanner);
return !ROOT_PROCESS_WHITELIST_PATTERN.matcher(name).matches()
&& (rootUid || rootGid);
} finally {
if (scanner != null) {
scanner.close();
}
}
}
/**
* Get the status {@link File} that has name:value pairs.
* <pre>
* Name: init
* ...
* Uid: 0 0 0 0
* Gid: 0 0 0 0
* </pre>
*/
private static File getProcessStatus(File processDir) {
return new File(processDir, "status");
}
/**
* Convenience method to move the scanner's position to the point after the given token.
*
* @param scanner to call next() until the token is found
* @param token to find like "Name:"
* @return scanner after finding token
*/
private static Scanner findToken(Scanner scanner, String token) {
while (true) {
String next = scanner.next();
if (next.equals(token)) {
return scanner;
}
}
// Scanner will exhaust input and throw an exception before getting here.
}
/**
* Uid and Gid lines have four values: "Uid: 0 0 0 0"
*
* @param scanner that has just processed the "Uid:" or "Gid:" token
* @return whether or not any of the ids are root
*/
private static boolean hasRootId(Scanner scanner) {
int realUid = scanner.nextInt();
int effectiveUid = scanner.nextInt();
int savedSetUid = scanner.nextInt();
int fileSystemUid = scanner.nextInt();
return realUid == 0 || effectiveUid == 0 || savedSetUid == 0 || fileSystemUid == 0;
}
/** Returns the name of the process corresponding to its process directory in /proc. */
private static String getProcessName(File processDir) throws FileNotFoundException {
File status = getProcessStatus(processDir);
Scanner scanner = new Scanner(status);
try {
scanner = findToken(scanner, "Name:");
return scanner.next();
} finally {
scanner.close();
}
}
}