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/*
* Copyright (C) 2012 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.
*/
#define TRACE_TAG AUTH
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if defined(__linux__)
#include <sys/inotify.h>
#endif
#include <map>
#include <mutex>
#include <set>
#include <string>
#include <android-base/errors.h>
#include <android-base/file.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <crypto_utils/android_pubkey.h>
#include <openssl/base64.h>
#include <openssl/evp.h>
#include <openssl/objects.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>
#include "adb.h"
#include "adb_auth.h"
#include "adb_io.h"
#include "adb_utils.h"
#include "sysdeps.h"
#include "transport.h"
static std::mutex& g_keys_mutex = *new std::mutex;
static std::map<std::string, std::shared_ptr<RSA>>& g_keys =
*new std::map<std::string, std::shared_ptr<RSA>>;
static std::map<int, std::string>& g_monitored_paths = *new std::map<int, std::string>;
static bool calculate_public_key(std::string* out, RSA* private_key) {
uint8_t binary_key_data[ANDROID_PUBKEY_ENCODED_SIZE];
if (!android_pubkey_encode(private_key, binary_key_data, sizeof(binary_key_data))) {
LOG(ERROR) << "Failed to convert to public key";
return false;
}
size_t expected_length;
if (!EVP_EncodedLength(&expected_length, sizeof(binary_key_data))) {
LOG(ERROR) << "Public key too large to base64 encode";
return false;
}
out->resize(expected_length);
size_t actual_length = EVP_EncodeBlock(reinterpret_cast<uint8_t*>(out->data()), binary_key_data,
sizeof(binary_key_data));
out->resize(actual_length);
return true;
}
static int generate_key(const std::string& file) {
LOG(INFO) << "generate_key(" << file << ")...";
mode_t old_mask;
FILE *f = nullptr;
int ret = 0;
EVP_PKEY* pkey = EVP_PKEY_new();
BIGNUM* exponent = BN_new();
RSA* rsa = RSA_new();
if (!pkey || !exponent || !rsa) {
LOG(ERROR) << "Failed to allocate key";
goto out;
}
BN_set_word(exponent, RSA_F4);
RSA_generate_key_ex(rsa, 2048, exponent, nullptr);
EVP_PKEY_set1_RSA(pkey, rsa);
old_mask = umask(077);
f = fopen(file.c_str(), "w");
if (!f) {
PLOG(ERROR) << "Failed to open " << file;
umask(old_mask);
goto out;
}
umask(old_mask);
if (!PEM_write_PrivateKey(f, pkey, nullptr, nullptr, 0, nullptr, nullptr)) {
D("Failed to write key");
goto out;
}
ret = 1;
out:
if (f) fclose(f);
EVP_PKEY_free(pkey);
RSA_free(rsa);
BN_free(exponent);
return ret;
}
static std::string hash_key(RSA* key) {
unsigned char* pubkey = nullptr;
int len = i2d_RSA_PUBKEY(key, &pubkey);
if (len < 0) {
LOG(ERROR) << "failed to encode RSA public key";
return std::string();
}
std::string result;
result.resize(SHA256_DIGEST_LENGTH);
SHA256(pubkey, len, reinterpret_cast<unsigned char*>(&result[0]));
OPENSSL_free(pubkey);
return result;
}
static std::shared_ptr<RSA> read_key_file(const std::string& file) {
std::unique_ptr<FILE, decltype(&fclose)> fp(fopen(file.c_str(), "r"), fclose);
if (!fp) {
PLOG(ERROR) << "Failed to open '" << file << "'";
return nullptr;
}
RSA* key = RSA_new();
if (!PEM_read_RSAPrivateKey(fp.get(), &key, nullptr, nullptr)) {
LOG(ERROR) << "Failed to read key";
RSA_free(key);
return nullptr;
}
return std::shared_ptr<RSA>(key, RSA_free);
}
static bool load_key(const std::string& file) {
std::shared_ptr<RSA> key = read_key_file(file);
if (!key) {
return false;
}
std::lock_guard<std::mutex> lock(g_keys_mutex);
std::string fingerprint = hash_key(key.get());
if (g_keys.find(fingerprint) != g_keys.end()) {
LOG(INFO) << "ignoring already-loaded key: " << file;
} else {
g_keys[fingerprint] = std::move(key);
}
return true;
}
static bool load_keys(const std::string& path, bool allow_dir = true) {
LOG(INFO) << "load_keys '" << path << "'...";
struct stat st;
if (stat(path.c_str(), &st) != 0) {
PLOG(ERROR) << "failed to stat '" << path << "'";
return false;
}
if (S_ISREG(st.st_mode)) {
return load_key(path);
} else if (S_ISDIR(st.st_mode)) {
if (!allow_dir) {
// inotify isn't recursive. It would break expectations to load keys in nested
// directories but not monitor them for new keys.
LOG(WARNING) << "refusing to recurse into directory '" << path << "'";
return false;
}
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(path.c_str()), closedir);
if (!dir) {
PLOG(ERROR) << "failed to open directory '" << path << "'";
return false;
}
bool result = false;
while (struct dirent* dent = readdir(dir.get())) {
std::string name = dent->d_name;
// We can't use dent->d_type here because it's not available on Windows.
if (name == "." || name == "..") {
continue;
}
if (!android::base::EndsWith(name, ".adb_key")) {
LOG(INFO) << "skipping non-adb_key '" << path << "/" << name << "'";
continue;
}
result |= load_key((path + OS_PATH_SEPARATOR + name));
}
return result;
}
LOG(ERROR) << "unexpected type for '" << path << "': 0x" << std::hex << st.st_mode;
return false;
}
static std::string get_user_key_path() {
return adb_get_android_dir_path() + OS_PATH_SEPARATOR + "adbkey";
}
static bool generate_userkey() {
std::string path = get_user_key_path();
if (path.empty()) {
PLOG(ERROR) << "Error getting user key filename";
return false;
}
struct stat buf;
if (stat(path.c_str(), &buf) == -1) {
LOG(INFO) << "User key '" << path << "' does not exist...";
if (!generate_key(path)) {
LOG(ERROR) << "Failed to generate new key";
return false;
}
}
return load_key(path);
}
static std::set<std::string> get_vendor_keys() {
const char* adb_keys_path = getenv("ADB_VENDOR_KEYS");
if (adb_keys_path == nullptr) {
return std::set<std::string>();
}
std::set<std::string> result;
for (const auto& path : android::base::Split(adb_keys_path, ENV_PATH_SEPARATOR_STR)) {
result.emplace(path);
}
return result;
}
std::deque<std::shared_ptr<RSA>> adb_auth_get_private_keys() {
std::deque<std::shared_ptr<RSA>> result;
// Copy all the currently known keys.
std::lock_guard<std::mutex> lock(g_keys_mutex);
for (const auto& it : g_keys) {
result.push_back(it.second);
}
// Add a sentinel to the list. Our caller uses this to mean "out of private keys,
// but try using the public key" (the empty deque could otherwise mean this _or_
// that this function hasn't been called yet to request the keys).
result.push_back(nullptr);
return result;
}
static std::string adb_auth_sign(RSA* key, const char* token, size_t token_size) {
if (token_size != TOKEN_SIZE) {
D("Unexpected token size %zd", token_size);
return nullptr;
}
std::string result;
result.resize(MAX_PAYLOAD);
unsigned int len;
if (!RSA_sign(NID_sha1, reinterpret_cast<const uint8_t*>(token), token_size,
reinterpret_cast<uint8_t*>(&result[0]), &len, key)) {
return std::string();
}
result.resize(len);
D("adb_auth_sign len=%d", len);
return result;
}
static bool pubkey_from_privkey(std::string* out, const std::string& path) {
std::shared_ptr<RSA> privkey = read_key_file(path);
if (!privkey) {
return false;
}
return calculate_public_key(out, privkey.get());
}
std::string adb_auth_get_userkey() {
std::string path = get_user_key_path();
if (path.empty()) {
PLOG(ERROR) << "Error getting user key filename";
return "";
}
std::string result;
if (!pubkey_from_privkey(&result, path)) {
return "";
}
return result;
}
int adb_auth_keygen(const char* filename) {
return (generate_key(filename) == 0);
}
int adb_auth_pubkey(const char* filename) {
std::string pubkey;
if (!pubkey_from_privkey(&pubkey, filename)) {
return 1;
}
pubkey.push_back('\n');
return WriteFdExactly(STDOUT_FILENO, pubkey.data(), pubkey.size()) ? 0 : 1;
}
#if defined(__linux__)
static void adb_auth_inotify_update(int fd, unsigned fd_event, void*) {
LOG(INFO) << "adb_auth_inotify_update called";
if (!(fd_event & FDE_READ)) {
return;
}
char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
while (true) {
ssize_t rc = TEMP_FAILURE_RETRY(unix_read(fd, buf, sizeof(buf)));
if (rc == -1) {
if (errno == EAGAIN) {
LOG(INFO) << "done reading inotify fd";
break;
}
PLOG(FATAL) << "read of inotify event failed";
}
// The read potentially returned multiple events.
char* start = buf;
char* end = buf + rc;
while (start < end) {
inotify_event* event = reinterpret_cast<inotify_event*>(start);
auto root_it = g_monitored_paths.find(event->wd);
if (root_it == g_monitored_paths.end()) {
LOG(FATAL) << "observed inotify event for unmonitored path, wd = " << event->wd;
}
std::string path = root_it->second;
if (event->len > 0) {
path += '/';
path += event->name;
}
if (event->mask & (IN_CREATE | IN_MOVED_TO)) {
if (event->mask & IN_ISDIR) {
LOG(INFO) << "ignoring new directory at '" << path << "'";
} else {
LOG(INFO) << "observed new file at '" << path << "'";
load_keys(path, false);
}
} else {
LOG(WARNING) << "unmonitored event for " << path << ": 0x" << std::hex
<< event->mask;
}
start += sizeof(struct inotify_event) + event->len;
}
}
}
static void adb_auth_inotify_init(const std::set<std::string>& paths) {
LOG(INFO) << "adb_auth_inotify_init...";
int infd = inotify_init1(IN_CLOEXEC | IN_NONBLOCK);
if (infd < 0) {
PLOG(ERROR) << "failed to create inotify fd";
return;
}
for (const std::string& path : paths) {
int wd = inotify_add_watch(infd, path.c_str(), IN_CREATE | IN_MOVED_TO);
if (wd < 0) {
PLOG(ERROR) << "failed to inotify_add_watch on path '" << path;
continue;
}
g_monitored_paths[wd] = path;
LOG(INFO) << "watch descriptor " << wd << " registered for " << path;
}
fdevent* event = fdevent_create(infd, adb_auth_inotify_update, nullptr);
fdevent_add(event, FDE_READ);
}
#endif
void adb_auth_init() {
LOG(INFO) << "adb_auth_init...";
if (!generate_userkey()) {
LOG(ERROR) << "Failed to generate user key";
return;
}
const auto& key_paths = get_vendor_keys();
#if defined(__linux__)
adb_auth_inotify_init(key_paths);
#endif
for (const std::string& path : key_paths) {
load_keys(path);
}
}
static void send_auth_publickey(atransport* t) {
LOG(INFO) << "Calling send_auth_publickey";
std::string key = adb_auth_get_userkey();
if (key.empty()) {
D("Failed to get user public key");
return;
}
if (key.size() >= MAX_PAYLOAD_V1) {
D("User public key too large (%zu B)", key.size());
return;
}
apacket* p = get_apacket();
p->msg.command = A_AUTH;
p->msg.arg0 = ADB_AUTH_RSAPUBLICKEY;
// adbd expects a null-terminated string.
p->payload.assign(key.data(), key.data() + key.size() + 1);
p->msg.data_length = p->payload.size();
send_packet(p, t);
}
void send_auth_response(const char* token, size_t token_size, atransport* t) {
std::shared_ptr<RSA> key = t->NextKey();
if (key == nullptr) {
// No more private keys to try, send the public key.
t->SetConnectionState(kCsUnauthorized);
t->SetConnectionEstablished(true);
send_auth_publickey(t);
return;
}
LOG(INFO) << "Calling send_auth_response";
apacket* p = get_apacket();
std::string result = adb_auth_sign(key.get(), token, token_size);
if (result.empty()) {
D("Error signing the token");
put_apacket(p);
return;
}
p->msg.command = A_AUTH;
p->msg.arg0 = ADB_AUTH_SIGNATURE;
p->payload.assign(result.begin(), result.end());
p->msg.data_length = p->payload.size();
send_packet(p, t);
}