platform_system_core/libnativeloader/public_libraries.cpp

/*
 * Copyright (C) 2019 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 LOG_TAG "nativeloader"

#include "public_libraries.h"

#include <dirent.h>

#include <algorithm>
#include <memory>

#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <log/log.h>

#include "utils.h"

namespace android::nativeloader {

using namespace std::string_literals;

namespace {

constexpr const char* kDefaultPublicLibrariesFile = "/etc/public.libraries.txt";
constexpr const char* kExtendedPublicLibrariesFilePrefix = "public.libraries-";
constexpr const char* kExtendedPublicLibrariesFileSuffix = ".txt";
constexpr const char* kVendorPublicLibrariesFile = "/vendor/etc/public.libraries.txt";
constexpr const char* kLlndkLibrariesFile = "/system/etc/llndk.libraries.txt";
constexpr const char* kVndkLibrariesFile = "/system/etc/vndksp.libraries.txt";

const std::vector<const std::string> kRuntimePublicLibraries = {
    "libicuuc.so",
    "libicui18n.so",
};

constexpr const char* kRuntimeApexLibPath = "/apex/com.android.runtime/" LIB;

// TODO(b/130388701): do we need this?
std::string root_dir() {
  static const char* android_root_env = getenv("ANDROID_ROOT");
  return android_root_env != nullptr ? android_root_env : "/system";
}

bool debuggable() {
  static bool debuggable = android::base::GetBoolProperty("ro.debuggable", false);
  return debuggable;
}

std::string vndk_version_str() {
  static std::string version = android::base::GetProperty("ro.vndk.version", "");
  if (version != "" && version != "current") {
    return "." + version;
  }
  return "";
}

// For debuggable platform builds use ANDROID_ADDITIONAL_PUBLIC_LIBRARIES environment
// variable to add libraries to the list. This is intended for platform tests only.
std::string additional_public_libraries() {
  if (debuggable()) {
    const char* val = getenv("ANDROID_ADDITIONAL_PUBLIC_LIBRARIES");
    return val ? val : "";
  }
  return "";
}

void InsertVndkVersionStr(std::string* file_name) {
  CHECK(file_name != nullptr);
  size_t insert_pos = file_name->find_last_of(".");
  if (insert_pos == std::string::npos) {
    insert_pos = file_name->length();
  }
  file_name->insert(insert_pos, vndk_version_str());
}

const std::function<bool(const std::string&, std::string*)> always_true =
    [](const std::string&, std::string*) { return true; };

bool ReadConfig(const std::string& configFile, std::vector<std::string>* sonames,
                const std::function<bool(const std::string& /* soname */,
                                         std::string* /* error_msg */)>& check_soname,
                std::string* error_msg = nullptr) {
  // Read list of public native libraries from the config file.
  std::string file_content;
  if (!base::ReadFileToString(configFile, &file_content)) {
    if (error_msg) *error_msg = strerror(errno);
    return false;
  }

  std::vector<std::string> lines = base::Split(file_content, "\n");

  for (auto& line : lines) {
    auto trimmed_line = base::Trim(line);
    if (trimmed_line[0] == '#' || trimmed_line.empty()) {
      continue;
    }
    size_t space_pos = trimmed_line.rfind(' ');
    if (space_pos != std::string::npos) {
      std::string type = trimmed_line.substr(space_pos + 1);
      if (type != "32" && type != "64") {
        if (error_msg) *error_msg = "Malformed line: " + line;
        return false;
      }
#if defined(__LP64__)
      // Skip 32 bit public library.
      if (type == "32") {
        continue;
      }
#else
      // Skip 64 bit public library.
      if (type == "64") {
        continue;
      }
#endif
      trimmed_line.resize(space_pos);
    }

    if (check_soname(trimmed_line, error_msg)) {
      sonames->push_back(trimmed_line);
    } else {
      return false;
    }
  }
  return true;
}

void ReadExtensionLibraries(const char* dirname, std::vector<std::string>* sonames) {
  std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(dirname), closedir);
  if (dir != nullptr) {
    // Failing to opening the dir is not an error, which can happen in
    // webview_zygote.
    while (struct dirent* ent = readdir(dir.get())) {
      if (ent->d_type != DT_REG && ent->d_type != DT_LNK) {
        continue;
      }
      const std::string filename(ent->d_name);
      std::string_view fn = filename;
      if (android::base::ConsumePrefix(&fn, kExtendedPublicLibrariesFilePrefix) &&
          android::base::ConsumeSuffix(&fn, kExtendedPublicLibrariesFileSuffix)) {
        const std::string company_name(fn);
        const std::string config_file_path = dirname + "/"s + filename;
        LOG_ALWAYS_FATAL_IF(
            company_name.empty(),
            "Error extracting company name from public native library list file path \"%s\"",
            config_file_path.c_str());

        std::string error_msg;

        LOG_ALWAYS_FATAL_IF(
            !ReadConfig(config_file_path, sonames,
                        [&company_name](const std::string& soname, std::string* error_msg) {
                          if (android::base::StartsWith(soname, "lib") &&
                              android::base::EndsWith(soname, "." + company_name + ".so")) {
                            return true;
                          } else {
                            *error_msg = "Library name \"" + soname +
                                         "\" does not end with the company name: " + company_name +
                                         ".";
                            return false;
                          }
                        },
                        &error_msg),
            "Error reading public native library list from \"%s\": %s", config_file_path.c_str(),
            error_msg.c_str());
      }
    }
  }
}

static std::string InitDefaultPublicLibraries() {
  std::string config_file = root_dir() + kDefaultPublicLibrariesFile;
  std::vector<std::string> sonames;
  std::string error_msg;
  LOG_ALWAYS_FATAL_IF(!ReadConfig(config_file, &sonames, always_true, &error_msg),
                      "Error reading public native library list from \"%s\": %s",
                      config_file.c_str(), error_msg.c_str());

  std::string additional_libs = additional_public_libraries();
  if (!additional_libs.empty()) {
    auto vec = base::Split(additional_libs, ":");
    std::copy(vec.begin(), vec.end(), std::back_inserter(sonames));
  }

  // Remove the public libs in the runtime namespace.
  // These libs are listed in public.android.txt, but we don't want the rest of android
  // in default namespace to dlopen the libs.
  // For example, libicuuc.so is exposed to classloader namespace from runtime namespace.
  // Unfortunately, it does not have stable C symbols, and default namespace should only use
  // stable symbols in libandroidicu.so. http://b/120786417
  for (const std::string& lib_name : kRuntimePublicLibraries) {
    std::string path(kRuntimeApexLibPath);
    path.append("/").append(lib_name);

    struct stat s;
    // Do nothing if the path in /apex does not exist.
    // Runtime APEX must be mounted since libnativeloader is in the same APEX
    if (stat(path.c_str(), &s) != 0) {
      continue;
    }

    auto it = std::find(sonames.begin(), sonames.end(), lib_name);
    if (it != sonames.end()) {
      sonames.erase(it);
    }
  }
  return android::base::Join(sonames, ':');
}

static std::string InitRuntimePublicLibraries() {
  CHECK(sizeof(kRuntimePublicLibraries) > 0);
  std::string list = android::base::Join(kRuntimePublicLibraries, ":");

  std::string additional_libs = additional_public_libraries();
  if (!additional_libs.empty()) {
    list = list + ':' + additional_libs;
  }
  return list;
}

static std::string InitVendorPublicLibraries() {
  // This file is optional, quietly ignore if the file does not exist.
  std::vector<std::string> sonames;
  ReadConfig(kVendorPublicLibrariesFile, &sonames, always_true, nullptr);
  return android::base::Join(sonames, ':');
}

// read /system/etc/public.libraries-<companyname>.txt and
// /product/etc/public.libraries-<companyname>.txt which contain partner defined
// system libs that are exposed to apps. The libs in the txt files must be
// named as lib<name>.<companyname>.so.
static std::string InitExtendedPublicLibraries() {
  std::vector<std::string> sonames;
  ReadExtensionLibraries("/system/etc", &sonames);
  ReadExtensionLibraries("/product/etc", &sonames);
  return android::base::Join(sonames, ':');
}

static std::string InitLlndkLibraries() {
  std::string config_file = kLlndkLibrariesFile;
  InsertVndkVersionStr(&config_file);
  std::vector<std::string> sonames;
  ReadConfig(config_file, &sonames, always_true, nullptr);
  return android::base::Join(sonames, ':');
}

static std::string InitVndkspLibraries() {
  std::string config_file = kVndkLibrariesFile;
  InsertVndkVersionStr(&config_file);
  std::vector<std::string> sonames;
  ReadConfig(config_file, &sonames, always_true, nullptr);
  return android::base::Join(sonames, ':');
}

}  // namespace

const std::string& default_public_libraries() {
  static std::string list = InitDefaultPublicLibraries();
  return list;
}

const std::string& runtime_public_libraries() {
  static std::string list = InitRuntimePublicLibraries();
  return list;
}

const std::string& vendor_public_libraries() {
  static std::string list = InitVendorPublicLibraries();
  return list;
}

const std::string& extended_public_libraries() {
  static std::string list = InitExtendedPublicLibraries();
  return list;
}

const std::string& llndk_libraries() {
  static std::string list = InitLlndkLibraries();
  return list;
}

const std::string& vndksp_libraries() {
  static std::string list = InitVndkspLibraries();
  return list;
}

}  // namespace android::nativeloader