diff options
Diffstat (limited to 'tunnel/src/main/java/com/wireguard/android')
| -rw-r--r-- | tunnel/src/main/java/com/wireguard/android/util/ModuleLoader.java | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/tunnel/src/main/java/com/wireguard/android/util/ModuleLoader.java b/tunnel/src/main/java/com/wireguard/android/util/ModuleLoader.java new file mode 100644 index 00000000..f09d9a87 --- /dev/null +++ b/tunnel/src/main/java/com/wireguard/android/util/ModuleLoader.java @@ -0,0 +1,186 @@ +/* + * Copyright © 2019-2020 WireGuard LLC. All Rights Reserved. + * SPDX-License-Identifier: Apache-2.0 + */ + +package com.wireguard.android.util; + +import android.content.Context; +import android.system.OsConstants; +import android.util.Base64; + +import com.wireguard.android.util.RootShell.RootShellException; + +import net.i2p.crypto.eddsa.EdDSAEngine; +import net.i2p.crypto.eddsa.EdDSAPublicKey; +import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable; +import net.i2p.crypto.eddsa.spec.EdDSAParameterSpec; +import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec; + +import java.io.File; +import java.io.FileOutputStream; +import java.io.IOException; +import java.io.InputStream; +import java.net.HttpURLConnection; +import java.net.URL; +import java.nio.charset.StandardCharsets; +import java.security.InvalidParameterException; +import java.security.MessageDigest; +import java.security.NoSuchAlgorithmException; +import java.security.Signature; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +import androidx.annotation.Nullable; + +public class ModuleLoader { + private static final String MODULE_PUBLIC_KEY_BASE64 = "RWRmHuT9PSqtwfsLtEx+QS06BJtLgFYteL9WCNjH7yuyu5Y1DieSN7If"; + private static final String MODULE_LIST_URL = "https://download.wireguard.com/android-module/modules.txt.sig"; + private static final String MODULE_URL = "https://download.wireguard.com/android-module/%s"; + private static final String MODULE_NAME = "wireguard-%s.ko"; + + private final RootShell rootShell; + private final String userAgent; + private final File moduleDir; + private final File tmpDir; + + public ModuleLoader(final Context context, final RootShell rootShell, final String userAgent) { + moduleDir = new File(context.getCacheDir(), "kmod"); + tmpDir = new File(context.getCacheDir(), "tmp"); + this.rootShell = rootShell; + this.userAgent = userAgent; + } + + public boolean moduleMightExist() { + return moduleDir.exists() && moduleDir.isDirectory(); + } + + public void loadModule() throws IOException, RootShellException { + rootShell.run(null, String.format("insmod \"%s/wireguard-$(sha256sum /proc/version|cut -d ' ' -f 1).ko\"", moduleDir.getAbsolutePath())); + } + + public static boolean isModuleLoaded() { + return new File("/sys/module/wireguard").exists(); + } + + private static final class Sha256Digest { + private byte[] bytes; + private Sha256Digest(final String hex) { + if (hex.length() != 64) + throw new InvalidParameterException("SHA256 hashes must be 32 bytes long"); + bytes = new byte[32]; + for (int i = 0; i < 32; ++i) + bytes[i] = (byte)Integer.parseInt(hex.substring(i * 2, i * 2 + 2), 16); + } + } + + @Nullable + private Map<String, Sha256Digest> verifySignedHashes(final String signifyDigest) { + final byte[] publicKeyBytes = Base64.decode(MODULE_PUBLIC_KEY_BASE64, Base64.DEFAULT); + + if (publicKeyBytes == null || publicKeyBytes.length != 32 + 10 || publicKeyBytes[0] != 'E' || publicKeyBytes[1] != 'd') + return null; + + final String[] lines = signifyDigest.split("\n", 3); + if (lines.length != 3) + return null; + if (!lines[0].startsWith("untrusted comment: ")) + return null; + + final byte[] signatureBytes = Base64.decode(lines[1], Base64.DEFAULT); + if (signatureBytes == null || signatureBytes.length != 64 + 10) + return null; + for (int i = 0; i < 10; ++i) { + if (signatureBytes[i] != publicKeyBytes[i]) + return null; + } + + try { + EdDSAParameterSpec parameterSpec = EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.ED_25519); + Signature signature = new EdDSAEngine(MessageDigest.getInstance(parameterSpec.getHashAlgorithm())); + byte[] rawPublicKeyBytes = new byte[32]; + System.arraycopy(publicKeyBytes, 10, rawPublicKeyBytes, 0, 32); + signature.initVerify(new EdDSAPublicKey(new EdDSAPublicKeySpec(rawPublicKeyBytes, parameterSpec))); + signature.update(lines[2].getBytes(StandardCharsets.UTF_8)); + if (!signature.verify(signatureBytes, 10, 64)) + return null; + } catch (final Exception ignored) { + return null; + } + + Map<String, Sha256Digest> hashes = new HashMap<>(); + for (final String line : lines[2].split("\n")) { + final String[] components = line.split(" ", 2); + if (components.length != 2) + return null; + try { + hashes.put(components[1], new Sha256Digest(components[0])); + } catch (final Exception ignored) { + return null; + } + } + return hashes; + } + + public Integer download() throws IOException, RootShellException, NoSuchAlgorithmException { + final List<String> output = new ArrayList<>(); + rootShell.run(output, "sha256sum /proc/version|cut -d ' ' -f 1"); + if (output.size() != 1 || output.get(0).length() != 64) + throw new InvalidParameterException("Invalid sha256 of /proc/version"); + final String moduleName = String.format(MODULE_NAME, output.get(0)); + HttpURLConnection connection = (HttpURLConnection)new URL(MODULE_LIST_URL).openConnection(); + connection.setRequestProperty("User-Agent", userAgent); + connection.connect(); + if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) + throw new IOException("Hash list could not be found"); + byte[] input = new byte[1024 * 1024 * 3 /* 3MiB */]; + int len; + try (final InputStream inputStream = connection.getInputStream()) { + len = inputStream.read(input); + } + if (len <= 0) + throw new IOException("Hash list was empty"); + final Map<String, Sha256Digest> modules = verifySignedHashes(new String(input, 0, len, StandardCharsets.UTF_8)); + if (modules == null) + throw new InvalidParameterException("The signature did not verify or invalid hash list format"); + if (!modules.containsKey(moduleName)) + return OsConstants.ENOENT; + connection = (HttpURLConnection)new URL(String.format(MODULE_URL, moduleName)).openConnection(); + connection.setRequestProperty("User-Agent", userAgent); + connection.connect(); + if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) + throw new IOException("Module file could not be found, despite being on hash list"); + + tmpDir.mkdirs(); + moduleDir.mkdir(); + File tempFile = null; + try { + tempFile = File.createTempFile("UNVERIFIED-", null, tmpDir); + MessageDigest digest = MessageDigest.getInstance("SHA-256"); + try (final InputStream inputStream = connection.getInputStream(); + final FileOutputStream outputStream = new FileOutputStream(tempFile)) { + int total = 0; + while ((len = inputStream.read(input)) > 0) { + total += len; + if (total > 1024 * 1024 * 15 /* 15 MiB */) + throw new IOException("File too big"); + outputStream.write(input, 0, len); + digest.update(input, 0, len); + } + outputStream.getFD().sync(); + } + if (!Arrays.equals(digest.digest(), modules.get(moduleName).bytes)) + throw new IOException("Incorrect file hash"); + + if (!tempFile.renameTo(new File(moduleDir, moduleName))) + throw new IOException("Unable to rename to final destination"); + } finally { + if (tempFile != null) + tempFile.delete(); + } + return OsConstants.EXIT_SUCCESS; + } +} |