Android7 对动态库访问的限制

从 Android 7.0 开始，系统将阻止应用动态链接非公开 NDK 库，这种库可能会导致您的应用崩溃。此行为变更旨在为跨平台更新和不同设备提供统一的应用体验。即使您的代码可能不会链接私有库，但您的应用中的第三方静态库可能会这么做。因此，所有开发者都应进行相应检查，确保他们的应用不会在运行 Android 7.0 的设备上崩溃。如果您的应用使用原生代码，则只能使用公开 NDK API。

动态库加载最终会调用这个函数，在这里会判断是否允许加载该动态库，最终就是logcat中显示的异常信息；

bionic\linker\linker.cpp

static bool load_library(android_namespace_t* ns,
                         LoadTask* task,
                         LoadTaskList* load_tasks,
                         int rtld_flags,
                         const std::string& realpath)
...
  if (!ns->is_accessible(realpath)) {
    // TODO(dimitry): workaround for http://b/26394120 - the grey-list
    const soinfo* needed_by = task->is_dt_needed() ? task->get_needed_by() : nullptr;
    if (is_greylisted(name, needed_by)) {
      // print warning only if needed by non-system library
      if (needed_by == nullptr || !is_system_library(needed_by->get_realpath())) {
        const soinfo* needed_or_dlopened_by = task->get_needed_by();
        const char* sopath = needed_or_dlopened_by == nullptr ? "(unknown)" :
                                                      needed_or_dlopened_by->get_realpath();
        DL_WARN("library \"%s\" (\"%s\") needed or dlopened by \"%s\" is not accessible for the namespace \"%s\""
                " - the access is temporarily granted as a workaround for http://b/26394120, note that the access"
                " will be removed in future releases of Android.",
                name, realpath.c_str(), sopath, ns->get_name());
        add_dlwarning(sopath, "unauthorized access to",  name);
      }
    } else {
      // do not load libraries if they are not accessible for the specified namespace.
      const char* needed_or_dlopened_by = task->get_needed_by() == nullptr ?
                                          "(unknown)" :
                                          task->get_needed_by()->get_realpath();

      DL_ERR("library \"%s\" needed or dlopened by \"%s\" is not accessible for the namespace \"%s\"",
             name, needed_or_dlopened_by, ns->get_name());

      PRINT("library \"%s\" (\"%s\") needed or dlopened by \"%s\" is not accessible for the"
            " namespace: [name=\"%s\", ld_library_paths=\"%s\", default_library_paths=\"%s\","
            " permitted_paths=\"%s\"]",
            name, realpath.c_str(),
            needed_or_dlopened_by,
            ns->get_name(),
            android::base::Join(ns->get_ld_library_paths(), ':').c_str(),
            android::base::Join(ns->get_default_library_paths(), ':').c_str(),
            android::base::Join(ns->get_permitted_paths(), ':').c_str());
      return false;
    }
  }
...
}