HarmonyOS Next Security Cornerstone: In-depth Analysis of Application Sandbox and Permission Mechanism

This article aims to deeply explore the technical details of the Huawei HarmonyOS Next system (as of API12 currently) in developing a multilingual e-commerce platform, and is summarized based on actual development practices. It mainly serves as a technical sharing and communication vehicle, and inevitably has omissions and errors. Colleagues are welcome to put forward valuable opinions and questions so that we can make progress together. This is original content, and any form of reproduction must indicate the source and the original author.

1. Overview of the HarmonyOS Next Security Architecture

In today's surging digital wave, smart phones carry all aspects of our lives. From daily communication to financial transactions, from personal privacy to corporate secrets, everything depends on the security of the mobile phone system. The HarmonyOS Next system stands out with its excellent security architecture, like an impregnable fortress, providing all-round protection for user data and system security. Its security architecture encompasses multiple key components, among which the application sandbox mechanism and the permission mechanism are the two most core pillars.

(1) Application Sandbox Mechanism: Building an Independent and Secure Operating Space

Imagine that each application in the HarmonyOS Next system is like living in an independent transparent bubble, and this bubble is the application sandbox. The application sandbox provides a completely independent operating environment for each application, just like assigning an independent and secure residence to each resident, and they cannot peek or interfere with each other at will.
From a technical implementation perspective, the kernel of HarmonyOS Next uses advanced isolation technology to strictly isolate key resources such as memory, file system, and network. This means that when application A runs in its own sandbox, it cannot directly access the files, data, or memory space of application B at all, effectively preventing the risks of data leakage and malicious tampering. For example, a social application cannot access the user data of another shopping application, even if they are running on the same device at the same time.

(2) Permission Mechanism: Fine-grained Management of Application Access Permissions

The permission mechanism is like the access control system of a castle, strictly controlling the access permissions of applications to system resources and user data. It accurately distributes corresponding permissions according to the different needs and trust levels of applications, ensuring that each application can only operate within the scope of its authorized permissions. This is like setting different levels of keys for each room in the castle, and only applications with the correct keys can enter the corresponding rooms to obtain the required resources.

2. Detailed Explanation of the Application Sandbox

(1) Sandbox Concept and Isolation Principle

The core concept of the application sandbox lies in isolation. Through the powerful functions of the operating system kernel, it creates an independent "territory" for each application. Within this territory, the application has its own independent process space, memory area, and file system. It is like each application is running on an independent island, and they can only see and use the resources on their own islands and cannot cross to other application islands.
For example, when you use a banking application and a game application simultaneously on your phone, the banking application cannot read the internal data of the game application, and vice versa. This isolation mechanism not only protects the data security of the application itself but also prevents malicious applications from attacking other applications or the system through vulnerabilities.

(2) Ways to Limit Data Access between Applications

1. Independent File System Each application has its own exclusive file storage area, just like each family has its own independent safe. The application can only perform read and write operations in its own file system and cannot directly access the files of other applications. This ensures that even if an application is compromised, an attacker cannot easily obtain the data of other applications.
2. Communication Restrictions Communication between applications is strictly managed. Only through specific interfaces and secure channels provided by the system can applications exchange data. For example, the distributed communication framework of HarmonyOS Next allows applications to communicate across devices under the premise of security. However, during the communication process, the data will be encrypted and undergo strict permission verification to ensure the confidentiality and integrity of the communication content. ## 3. Interpretation of Application Permissions ### (1) Permission Classification and Characteristics
3. system_grant (System-authorized) Permissions This type of permission mainly involves system-level operations and access to non-sensitive information. For example, permissions such as querying application basic information, configuring Bluetooth, and obtaining network information all belong to the system_grant type. These permissions are usually automatically granted by the system during application installation, and developers do not need to pop up a window to request additional authorization from users, which greatly simplifies the application initialization process and also ensures the reasonable allocation and orderly management of system resources.
4. user_grant (User-authorized) Permissions Permissions closely related to user privacy and sensitive operations belong to the user_grant type. For example, operations such as accessing the camera, microphone, reading the user's address book, and obtaining accurate location information all require explicit user authorization. When an application needs to use these permissions, it must pop up a window to request authorization from the user and clearly explain the reason and purpose of applying for the permission. This fully reflects the respect and protection of user privacy by HarmonyOS Next, allowing users to always have control over their private data. ### (2) Association between Permission Levels and Application APL Levels
5. Overview of APL Levels HarmonyOS Next introduces the APL (Ability Privilege Level) level to measure the permission application priority and capability range of an application. The APL level of an application is divided into three levels: normal, system_basic, and system_core, with the level increasing in sequence, representing that the permissions and access depth to system resources that the application can obtain also gradually increase.
6. Table Display of Corresponding Relationships | Application APL Level | Permission APL Level | Permission Description | |---|---|---| | normal | normal | Allows the application to access ordinary system resources outside the default rules, such as configuring Wi-Fi information and using the camera to take pictures. The opening of these system resources has a low risk to user privacy and other applications. | | system_basic | system_basic | Allows the application to access resources related to system basic services (basic functions provided or pre-installed by the system), such as system hardware and identity authentication. The opening of these system resources has a high risk to user privacy and other applications. Some permissions are restrictedly open to normal-level applications. | | system_core | system_core | Permissions to access the core resources of the operating system. This part of the system resources is the core service of the system, and if damaged, the operating system will not be able to operate normally. Only open to system applications. | For example, an ordinary game application may only have a normal APL level, and it can only apply for and use normal-level permissions, such as basic permissions such as network access and storage reading, and cannot obtain permissions related to system core functions. System-level applications, such as the settings application, may have a system_core APL level and can access and manage the core settings and resources of the system. ## 4. Analysis of the Access Control List (ACL) ### (1) The Important Role of ACL The access control list (ACL) plays the role of a "special pass" in the permission management system of HarmonyOS Next. It provides a legitimate way for applications that need to break through the常规权限限制, ensuring that under specific circumstances, applications can access higher-level permissions under strict security control. It is like opening a dedicated channel for some vehicles with special needs, but this channel also has strict traffic rules and approval processes. ### (2) The Process of Applying for Advanced Permissions through ACL Suppose an application with a normal APL level needs to access system_basic-level permissions (for example, access specific system hardware information) due to business expansion. First, the developer needs to carefully evaluate the application usage scenarios to ensure that the application for advanced permissions is reasonable and necessary. Then, submit detailed application materials to the application market (AppGallery Connect, AGC), including the reason for applying for the permission, usage scenario description, expected function implementation, etc. AGC will conduct a strict review based on the submitted materials. If the review is passed, the application will obtain the corresponding permission certificate. The developer declares and configures the permission in the code project according to the prescribed process. At runtime, the application requests permission from the system through the ACL mechanism, and the system will verify the legality of the application and the permission usage scenario again. Only when everything complies with the regulations will the application be granted temporary advanced permissions. ## 5. Summary and Outlook The application sandbox and permission mechanism of HarmonyOS Next jointly build a solid and reliable security foundation. The application sandbox fundamentally isolates the mutual interference and data leakage risks between applications, and the permission mechanism ensures the reasonable access of applications to system resources and user data through fine-grained permission classification, level management, and user authorization processes. The existence of ACL further enhances the flexibility of permission management and provides a feasible solution for permission requirements in special scenarios. Looking to the future, with the continuous development of technology and the increasing demand for security from users, the security mechanism of HarmonyOS Next will continue to evolve. We expect to see more intelligent and adaptive security strategies in future versions, further enhancing the security of user data and the level of privacy protection. At the same time, we also hope that developers can fully understand and utilize these security mechanisms to create more secure, reliable, and high-quality application experiences for users. In this digital age full of challenges and opportunities, HarmonyOS Next will continue to lead the development trend in the field of smart device security and escort the digital lives of users.