This article aims to deeply explore the technical details of the Huawei HarmonyOS Next system (up to API 12 as of now), and is summarized based on actual development practices. It mainly serves as a vehicle for technical sharing and communication. Mistakes and omissions are inevitable. Colleagues are welcome to put forward valuable opinions and questions so that we can make progress together. This article is original content, and any form of reprint must indicate the source and the original author.
1. Basics of Kernel Security
(1) Basic Principles
The kernel security of HarmonyOS Next is like a carefully designed fortress, and its basic principles are constructed around several key aspects. Firstly, in terms of access control, it implements strict permission management. Just like different areas in a castle have different levels of access control, it ensures that only authorized processes or threads can access specific kernel resources. For example, the key system call interfaces in the system kernel can only be called by core system processes with corresponding permissions, preventing ordinary applications from randomly modifying the key configurations of the system.
From the perspective of kernel architecture design, it adopts the concept of a microkernel architecture, minimizing and modularizing the kernel functions. This is similar to dividing the different functional areas in a castle into independent small castles. Each small castle (module) has its own defense system, and if one small castle has a problem, it will not easily affect other areas, effectively reducing the spread range of security risks.(2) Comparison of Common Kernel Security Vulnerabilities and Countermeasures
Common kernel security vulnerabilities, such as buffer overflow vulnerabilities, are like cracks in the city wall. Attackers can use these cracks to inject malicious code and gain control of the system. When traditional operating systems face such vulnerabilities, they usually need a long time to release patches for repair, and due to the complexity of the system architecture, there may also be problems with patch compatibility.
However, HarmonyOS Next has adopted a variety of proactive countermeasures. For buffer overflow issues, it strictly follows security coding standards during the code writing stage and conducts boundary checks. It's like ensuring that every brick fits tightly when building the city wall to prevent cracks from appearing. At the same time, it utilizes memory protection mechanisms, such as memory layout randomization, making it difficult for attackers to predict memory addresses. It's like the room numbers in the castle change randomly every day, confusing the enemies.
For example, to address kernel information leakage vulnerabilities, HarmonyOS Next implements strict access control and encryption processing for kernel data. Only authorized processes can obtain necessary kernel information, and the information is encrypted during transmission to prevent it from being stolen. This is like storing confidential documents in encrypted safes in the castle. Only specific personnel with the correct passwords can view them, and when passing the documents, sealed envelopes are used to ensure information security.2. Memory Security Management
(1) Security Mechanisms for Memory Allocation and Reclamation
The memory security management mechanism of HarmonyOS Next is like a meticulous butler, carefully managing the "storage space" of memory. In terms of memory allocation, it adopts a secure allocation algorithm to ensure that the memory space obtained by each process or thread is independent and secure. For example, when a new application program starts and requests memory, the system will allocate a suitable-sized space in the memory that is isolated from other applications according to the application's needs, just like assigning independent rooms to each guest in a hotel, and guests cannot freely enter each other's rooms.
In terms of memory reclamation, there is a sound garbage collection mechanism. When a process ends or no longer uses certain memory spaces, the system will promptly reclaim these memories to prevent memory leaks. This is like hotel staff immediately cleaning the room after a guest checks out, preparing for the next guest. Meanwhile, during the memory reclamation process, the data in the memory will be securely cleared to ensure that sensitive information will not remain in the memory and be obtained by other processes, just like thoroughly cleaning personal items in the room when checking out to prevent the remaining information from being used by others.(2) Code Example Demonstrating Memory Security Operations
The following is a simple ARKTS code example demonstrating how to perform secure memory allocation and release in HarmonyOS Next:
import memory from '@ohos.memory';
// Secure memory allocation
async function allocateMemory(): Promise<void> {
try {
const size: number = 1024; // Allocate 1024 bytes of memory
const memoryOptions: memory.AllocatorOptions = {
type: memory.MemoryType.HEAP,
flags: memory.MemoryFlag.PROT_READ | memory.MemoryFlag.PROT_WRITE
};
const allocatedMemory: Uint8Array = await memory.allocator.allocate(size, memoryOptions);
// Operations can be performed on the allocated memory here
console.log('Memory allocated successfully.');
} catch (err) {
console.error('Error allocating memory:', err);
}
}
// Secure memory release
async function freeMemory(): Promise<void> {
try {
const memoryAddress: number = 0x12345678; // Assume this is the memory address to be released
await memory.allocator.free(memoryAddress);
console.log('Memory freed successfully.');
} catch (err) {
console.error('Error freeing memory:', err);
}
}
In practical applications, memory is first securely allocated through the allocateMemory function according to the specified size and attributes. After using the memory, it is promptly released through the freeMemory function to ensure the security and efficiency of memory management.
3. Process and Thread Security
(1) Security Measures for Process Isolation and Thread Synchronization
Process isolation is one of the important means for HarmonyOS Next to ensure system security, just like creating an independent "sandbox" for each process. Each process runs within its own "sandbox" and cannot directly access the memory space and resources of other processes. For example, the process of a malicious application cannot peek at the user data in the processes of other normal applications, which effectively prevents malicious attacks and data theft between processes.
For thread synchronization, HarmonyOS Next provides multiple synchronization mechanisms, such as mutex locks and semaphores. Taking the mutex lock as an example, when multiple threads need to access shared resources, the mutex lock is like the lock on a toilet door (a bit funny but vivid). Only one thread is allowed to enter and access the shared resources at the same time, and other threads must wait. This ensures the consistency and correctness of shared resources in a multi-thread environment, preventing data races and errors.
(2) Practical Case Demonstrating the Importance of Process and Thread Security
Suppose we have an online payment system, including a user interface process, a payment processing process, and a database management process. The user interface process is responsible for receiving users' payment information, such as bank card numbers and passwords, and then passing this information to the payment processing process. The payment processing process needs to encrypt this information and interact with the database management process to verify user account information and complete the payment operation.
If there is no process isolation, malicious programs may invade the user interface process, steal users' payment information, or modify the encryption logic in the payment processing process, resulting in losses of users' funds. The process isolation mechanism of HarmonyOS Next ensures the independence of each process. Even if the user interface process is attacked, attackers cannot easily obtain the sensitive information in the payment processing process.
Inside the payment processing process, there may be multiple threads simultaneously processing payment requests from different users. If there is no thread synchronization mechanism, multiple threads may simultaneously write to the database, resulting in data chaos, such as duplicate deductions or incorrect recording of payment amounts. By using thread synchronization mechanisms such as mutex locks, the atomicity and orderliness of each payment request during the processing process are ensured, guaranteeing the safe and stable operation of the online payment system.
The kernel security enhancement strategies of HarmonyOS Next, from the basics of kernel security, memory security management to process and thread security, have comprehensively built a solid security defense line. These strategies not only improve the security of the system itself but also provide a reliable foundation for us developers, enabling applications developed on the HarmonyOS Next platform to better safeguard users' data security and system stability. In the future technological development, HarmonyOS Next will continue to innovate and optimize in the security field, bringing users a safer and more reliable intelligent experience.
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