Mandatory access control and protection method and system for network transmission file

Abstract

The invention discloses a mandatory access control and protection method and system for a network transmission file, and the method comprises the steps: a sender and a receiver carry out a series of access authority checks through a mandatory access mechanism before transmitting the file; the sender is allowed to transmit the target file to the receiver only when a series of access permission checks are passed; the series of access permission checking comprises file access permission checking of a sender process based on a BLP security model and a BIBA security model rule, file access permission checking for checking whether an intermediate service process transfers data and detecting the intermediate service process, and permission level checking of a receiver process; and the receiver stores part or all of the directory permission and the target file level check. The invention aims to solve the problem that file data is easily transmitted to a network link and a system environment which do not meet the authority in an existing file encryption transmission mode, and the confidentiality and the integrity of network transmission files are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of file transmission information security, and in particular to a mandatory access control and protection method and system for network transmission files. Background Art

[0002] In the field of information security, the core of data protection focuses on three basic characteristics: availability, integrity and confidentiality. Availability means that data can be accessed by authorized users at any time when needed, without being affected by hardware failures or other interruptions. Integrity ensures that data is not maliciously tampered with or unauthorizedly modified during the transaction process, and maintains the original state of the data. Confidentiality involves encryption protection of data to prevent unauthorized access and eavesdropping, and ensure data security. The goal of information security is to maintain these three characteristics to ensure data security.

[0003] In the network data transmission scenario, data transmission methods can be divided into two categories: network data packet transmission with high real-time requirements and large data flow transmission with high transmission efficiency. In the scenario of network file transmission, some files have high access permission requirements. For unauthorized access users or external entities, it is required that these files cannot be accessed to ensure the confidentiality and integrity of the files after transmission. The leakage of files is often caused by the file sender mistakenly sending the file to an unauthorized recipient, or to an unauthorized intermediate service process. In order to ensure the confidentiality of file transmission, the existing file transmission control method often adopts an encrypted transmission method. The file sender sends the key and the file to the recipient together. After receiving the file, the recipient decrypts the file through the corresponding password string to obtain the permission to access the file. For example, a file encryption transmission method and device disclosed in announcement number CN112311865B. However, after receiving the file, the unauthorized file recipient will have the risk of cracking the file encryption, and the confidentiality is poor. If the integrity level of the recipient is higher than that of the sender, the integrity of the recipient's information may be destroyed. In summary, the encrypted transmission method of the file is easy to transmit the file data to the network link and system environment that do not meet the authority, and the confidentiality and integrity are poor. Summary of the invention

[0004] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a mandatory access control and protection method for network transmitted files is provided. The present invention aims to solve the problem that the existing file encryption transmission method easily transmits file data to network links and system environments that do not meet the authority, thereby improving the confidentiality and integrity of network transmitted files.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A mandatory access control and protection method for network transmission files, comprising the following steps: a sender and a receiver use a mandatory access mechanism to perform a series of access rights checks before transmitting files, and the sender is allowed to transmit the target file to the receiver only when a series of access rights checks are passed, the series of access rights checks include a sender process access file rights check based on BLP security model and BIBA security model rules, a file access rights check of whether there is an intermediate service process transferring data and detecting the intermediate service process, a receiver process permission level check, a receiver storage directory permission check and a target file level check.

[0006] Optionally, the sending process access file permission check includes: S101, the sending process obtains the confidentiality level and integrity level of itself and the target file respectively; S102, using the security rules of the BLP security model to determine whether the sending process can read the target file according to the confidentiality level of the sending process and the target file, and using the security rules of the BIBA security model to determine whether the sending process can read the target file according to the integrity level of the sending process and the target file. If any of the above two judgments determines that the sending process cannot read the target file, then it is determined that the sending process access file permission check has failed; otherwise, it is determined that the sending process access file permission check has passed.

[0007] Optionally, the checking of whether there is an intermediate service process transferring data and detecting the access file permission of the intermediate service process includes: S201, the sender process determines whether the sender has an intermediate service process to transfer data. If there is no intermediate service process to transfer data, it is determined that the access file permission check of the intermediate service process has passed and exits; otherwise, jump to step S202; S202, the sending process obtains the confidentiality level and integrity level of the intermediate service process; S203, the sender uses the security rules of the BLP security model to determine whether the intermediate service process can read the target file based on the confidentiality level of the intermediate service process and the target file, and uses the security rules of the BIBA security model to determine whether the intermediate service process can read the target file based on the integrity level of the intermediate service process and the target file. If any of the above two judgments determines that the intermediate service process cannot read the target file, then the access file permission check of the intermediate service process is determined to have failed; otherwise, the access file permission check of the intermediate service process is determined to have passed.

[0008] Optionally, the receiving process permission level check includes: S301, the sending process packages a level request for obtaining the confidentiality level and integrity level of the receiving party into a data packet and sends it to the receiving party; S302, after the receiving party obtains the data packet of the confidentiality level and integrity level request sent by the sending party process, it obtains the confidentiality level and integrity level composition request reply packet data of the receiving party process for receiving the target file and returns it to the sending party process; S303, after the sending process obtains the request reply package data, it parses and obtains the confidentiality level and integrity level of the receiving process, and uses the security rules of the BLP security model to determine whether the receiving process can read the target file based on the confidentiality level of the receiving process and the target file, and uses the security rules of the BIBA security model to determine whether the receiving process can read the target file based on the integrity level of the receiving process and the target file. If any of the above two judgments determines that the receiving process cannot read the target file, the receiving process permission check is determined to have failed; otherwise, the receiving process permission check is determined to have passed.

[0009] Optionally, the receiving party storage directory permission and target file level check includes: S401, the sender sends the file name of the target file, the corresponding storage directory in the system, and the confidentiality level and integrity level of the target file to the receiver; S402, after receiving the information sent by the sender, the receiver obtains the confidentiality level and integrity level of the receiver process and the storage directory; uses the security rules of the BLP security model to determine whether the receiver process can access the storage directory according to the confidentiality level of the receiver process and the storage directory, and uses the security rules of the BIBA security model to determine whether the receiver process can access the storage directory according to the integrity level of the receiver process and the target file; if any of the above two judgments determines that the receiver process cannot access the storage directory, then it is finally determined that the receiver process cannot access the storage directory, otherwise it is finally determined that the receiver process can access the storage directory; S403, the receiving party packages the final determination result into a data packet and sends it to the sending party; S404, the sender determines the receiver's storage directory permission and target file level check based on the permission determination result of whether the receiver process in the data packet packaged and sent by the receiver can access the storage directory. If the receiver process can access the storage directory, then it is determined that the receiver's storage directory permission and target file level check have passed; otherwise, it is determined that the receiver's storage directory permission and target file level check have failed.

[0010] Optionally, the mandatory access control and protection method for network transmission files also includes, when the sender and the receiver are interacting with each other, using the HMAC mechanism to verify the validity of the message for the data to be transmitted: the sender generates a random number, calculates the sender's HMAC value using the data to be transmitted, the preset key and the random number, and then packages the data to be transmitted, the random number and the sender's HMAC value together into a data packet and sends it to the receiver; after receiving the data packet, the receiver calculates the receiver's HMAC value using the received data, the preset key and the random number, and determines whether the sender's HMAC value and the receiver's HMAC value are consistent. If they are consistent, the received data is determined to be valid; otherwise, the received data is determined to be invalid.

[0011] Optionally, the mandatory access mechanism is an SELinux mandatory access mechanism. Before the sender uses the mandatory access mechanism to perform a series of access permission judgments before the recipient transmits the file, the recipient and the sender respectively enable the SELinux mandatory access mode, the BLP security model and the BIBA security model. If either party fails to enable, the execution ends and exits; otherwise, the execution continues. After allowing the sender to transfer the target file to the recipient, the sender transmits the target file to the recipient, and the recipient receives the target file. The recipient sets the confidentiality level and integrity level of the corresponding file in the local storage directory according to the confidentiality level and integrity level of the target file sent by the sender, thereby completing the file transfer process.

[0012] In addition, the present invention also provides a mandatory access control and protection system for network transmission files, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the mandatory access control and protection method for network transmission files.

[0013] In addition, the present invention also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the mandatory access control and protection method for network transmission files through a processor.

[0014] In addition, the present invention also provides a computer program product, including a computer program or instructions, wherein the computer program or instructions are programmed or configured to execute the mandatory access control and protection method for network transmission files through a processor.

[0015] Compared with the prior art, the present invention mainly has the following advantages: The mandatory access control and protection method disclosed in the present invention utilizes a mandatory access mechanism to perform a series of access permission checks on the sender and the receiver before transmitting files, and the sender is allowed to transmit the target file to the receiver only when a series of access permission checks are passed. The series of access permission checks are based on the BLP security model and the BIBA security model rules. The BLP security model rules can ensure the confidentiality of the file, and the BIBA security model rules can protect the integrity of the information. The two security model rules are applied to the scenario of network transmission of files, which is conducive to preventing the file data from being transmitted to the network links and system environments that do not meet the permissions, thereby improving the confidentiality and integrity of the network transmission files. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a mandatory access control and protection method for network transmission files according to an embodiment of the present invention.

[0017] Figure 2 It is a schematic block diagram of using the HMAC mechanism to verify the validity of a message in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0019] In the process of network file transmission, the sender and the receiver are both determined according to the file sending flow direction. Therefore, when describing this embodiment, the sender is the file sending end and the receiver is the file acquiring end.

[0020] The BLP security model has a read-from-bottom and write-from-top security rule, which means that the subject can read objects with a lower or equal security level than him, but cannot read objects with a higher security level than him, and can write objects with a higher or equal security level than him, but cannot write objects with a lower security level than him. The BIBA security model has a read-from-top and write-from-bottom security rule, which means that the subject can read objects with a higher or equal integrity level than him, but cannot read objects with a lower integrity level than him, and can write objects with a lower integrity level than him, but cannot write objects with a higher integrity level than him.

[0021] like Figure 1 As shown, the mandatory access control and protection method for network transmission files of this embodiment includes the following steps: the sender and the receiver use the mandatory access mechanism to perform a series of access permission checks before transmitting the file, and the sender is allowed to transfer the target file to the receiver only when a series of access permission checks are passed. The series of access permission checks include a sender process access file permission check based on the BLP security model and BIBA security model rules, a file access permission check of whether there is an intermediate service process transferring data and detecting the intermediate service process, a receiver process permission level check, a receiver storage directory permission check and a target file level check.

[0022] In the mandatory access control and protection method for network transmission files of this embodiment, the sender and the receiver use a mandatory access mechanism to perform a series of access permission checks before transmitting files, and the sender is allowed to transmit the target file to the receiver only when a series of access permission checks are passed. The series of access permission checks are based on the BLP security model and the BIBA security model rules. The BLP security model rules can ensure the confidentiality of the file, and the BIBA security model rules can protect the integrity of the information. The two security model rules are applied to the scenario of network transmission files, which is conducive to preventing the file data from being transmitted to the network links and system environments that do not meet the permissions, thereby improving the confidentiality and integrity of the network transmission files.

[0023] Of course, in other embodiments, a series of access permission checks may also include a sender process access file permission check based on the BLP security model and BIBA security model rules, a check on whether there is an intermediate service process transferring data and detecting the intermediate service process's access file permission check, a receiver process permission level check, a receiver storage directory permission check, and a target file level check. The more checks there are, the more conducive it is to preventing file data from being transferred to network links and system environments that do not meet the permissions, and the better the confidentiality and integrity will be.

[0024] As an optional implementation mode, the file access permission check of the sending process in this embodiment includes: S101, the sending process obtains the confidentiality level and integrity level of itself and the target file respectively; S102, using the security rules of the BLP security model to determine whether the sending process can read the target file according to the confidentiality level of the sending process and the target file, and using the security rules of the BIBA security model to determine whether the sending process can read the target file according to the integrity level of the sending process and the target file. If any of the above two judgments determines that the sending process cannot read the target file, then it is determined that the sending process access file permission check has failed; otherwise, it is determined that the sending process access file permission check has passed.

[0025] As an optional implementation mode, in this embodiment, whether there is an intermediate service process transferring data and detecting the access file permission check of the intermediate service process includes: S201, the sender process determines whether the sender has an intermediate service process to transfer data. If there is no intermediate service process to transfer data, it is determined that the access file permission check of the intermediate service process has passed and exits; otherwise, jump to step S202; S202, the sending process obtains the confidentiality level and integrity level of the intermediate service process; S203, the sender uses the security rules of the BLP security model to determine whether the intermediate service process can read the target file based on the confidentiality level of the intermediate service process and the target file, and uses the security rules of the BIBA security model to determine whether the intermediate service process can read the target file based on the integrity level of the intermediate service process and the target file. If any of the above two judgments determines that the intermediate service process cannot read the target file, then the access file permission check of the intermediate service process is determined to have failed; otherwise, the access file permission check of the intermediate service process is determined to have passed.

[0026] As an optional implementation mode, the receiving process permission level check in this embodiment includes: S301, the sending process packages a level request for obtaining the confidentiality level and integrity level of the receiving party into a data packet and sends it to the receiving party; S302, after the receiving party obtains the data packet of the confidentiality level and integrity level request sent by the sending party process, it obtains the confidentiality level and integrity level composition request reply packet data of the receiving party process for receiving the target file and returns it to the sending party process; S303, after the sending process obtains the request reply package data, it parses and obtains the confidentiality level and integrity level of the receiving process, and uses the security rules of the BLP security model to determine whether the receiving process can read the target file based on the confidentiality level of the receiving process and the target file, and uses the security rules of the BIBA security model to determine whether the receiving process can read the target file based on the integrity level of the receiving process and the target file. If any of the above two judgments determines that the receiving process cannot read the target file, the receiving process permission check is determined to have failed; otherwise, the receiving process permission check is determined to have passed.

[0027] As an optional implementation method, the receiving party storage directory permission and target file level check in this embodiment include: S401, the sender sends the file name of the target file, the corresponding storage directory in the system, and the confidentiality level and integrity level of the target file to the receiver; S402, after receiving the information sent by the sender, the receiver obtains the confidentiality level and integrity level of the receiver process and the storage directory; uses the security rules of the BLP security model to determine whether the receiver process can access the storage directory according to the confidentiality level of the receiver process and the storage directory, and uses the security rules of the BIBA security model to determine whether the receiver process can access the storage directory according to the integrity level of the receiver process and the target file; if any of the above two judgments determines that the receiver process cannot access the storage directory, then it is finally determined that the receiver process cannot access the storage directory, otherwise it is finally determined that the receiver process can access the storage directory; S403, the receiving party packages the final determination result into a data packet and sends it to the sending party; S404, the sender determines the receiver's storage directory permission and target file level check based on the permission determination result of whether the receiver process in the data packet packaged and sent by the receiver can access the storage directory. If the receiver process can access the storage directory, then it is determined that the receiver's storage directory permission and target file level check have passed; otherwise, it is determined that the receiver's storage directory permission and target file level check have failed.

[0028] As an optional implementation method, when the sender sends the file data of the target file to the receiver, the confidentiality level and integrity level data of the target file will be sent synchronously. After the receiver receives the corresponding data, the target file will be written to the target directory, and the corresponding confidentiality level and integrity level of the target file in the target directory will be set, which is conducive to ensuring the confidentiality and integrity of the subsequent target file when it is transmitted again.

[0029] like Figure 2 As shown, as an optional implementation method, in order to ensure the authenticity and integrity of the data, in this embodiment, when the sender and the receiver are interacting with each other, the data to be transmitted uses the HMAC mechanism to verify the validity of the message: the sender generates a random number, calculates the sender's HMAC value with the data to be transmitted, the preset key and the random number, and then packages the data to be transmitted, the random number and the sender's HMAC value into a data packet and sends it to the receiver; after receiving the data packet, the receiver calculates the receiver's HMAC value with the received data, the preset key and the random number, and determines whether the sender's HMAC value and the receiver's HMAC value are consistent. If they are consistent, the received data is determined to be valid, otherwise the received data is determined to be invalid. The preset key can be preset through file storage, can be stored in the persistent area of ​​secure hardware, can also be preset through an external encryption card or preset through a built-in encryption card. It should be noted that if the sender and the receiver have a shared key, there is no need to pre-make the key.

[0030] As an optional implementation method, the mandatory access mechanism of this embodiment is the selinux mandatory access mechanism. Before the sender uses the mandatory access mechanism to perform a series of access rights judgments before the receiver transfers the file, the receiver and the sender respectively enable the selinux mandatory access mode, the BLP security model and the BIBA security model. If either party fails to enable, the process ends and exits; otherwise, the process continues; after the sender is allowed to transfer the target file to the receiver, the sender transmits the target file to the receiver, and the receiver receives the target file. The receiver sets the confidentiality level and integrity level of the corresponding file in the local storage directory according to the confidentiality level and integrity level of the target file sent by the sender, and completes the file transfer process. selinux is a mechanism that provides access control security policies for the linux kernel. It enhances the security of the operating system through mandatory access control, which is conducive to preventing malicious software and attackers from illegally accessing system resources. selinux divides system resources into different security contexts based on the domain-type mandatory access control model, and defines access rules between subjects and objects. By enforcing these rules, selinux can limit the access of processes to resources such as files, network ports, and processes, thereby helping to prevent potential security threats.

[0031] In addition, this embodiment also provides a mandatory access control and protection system for network transmission files, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute a mandatory access control and protection method for network transmission files.

[0032] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute a mandatory access control and protection method for network transmission files through a processor.

[0033] In addition, this embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute a mandatory access control and protection method for network transmission files through a processor.

[0034] Those skilled in the art should understand that the technical solutions provided by the embodiments of the present application may be in the form of methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0035] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A mandatory access control and protection method for network transmission files, characterized in that: The method comprises the following steps: the sender and the receiver use a mandatory access mechanism to perform a series of access permission checks before transmitting files, and the sender is allowed to transmit the target file to the receiver only when a series of access permission checks are passed, wherein the series of access permission checks include a sender process access file permission check based on the BLP security model and the BIBA security model rules, a file permission check to determine whether there is an intermediate service process transferring data and detecting the access file permission of the intermediate service process, a receiver process permission level check, a receiver storage directory permission check, and a target file level check, in part or all of these.

2. The mandatory access control and protection method for network transmission files according to claim 1 is characterized in that: The sending process access file permission check includes: S101, the sending process obtains the confidentiality level and integrity level of itself and the target file respectively; S102, using the security rules of the BLP security model to determine whether the sending process can read the target file according to the confidentiality level of the sending process and the target file, and using the security rules of the BIBA security model to determine whether the sending process can read the target file according to the integrity level of the sending process and the target file. If any of the above two judgments determines that the sending process cannot read the target file, then it is determined that the sending process access file permission check has failed; otherwise, it is determined that the sending process access file permission check has passed.

3. The mandatory access control and protection method for network transmission files according to claim 1 is characterized in that: The checking of whether there is an intermediate service process transferring data and detecting the access file authority of the intermediate service process includes: S201, the sender process determines whether the sender has an intermediate service process to transfer data. If there is no intermediate service process to transfer data, it is determined that the access file permission check of the intermediate service process has passed and exits; otherwise, jump to step S202; S202, the sending process obtains the confidentiality level and integrity level of the intermediate service process; S203, the sender uses the security rules of the BLP security model to determine whether the intermediate service process can read the target file based on the confidentiality level of the intermediate service process and the target file, and uses the security rules of the BIBA security model to determine whether the intermediate service process can read the target file based on the integrity level of the intermediate service process and the target file. If any of the above two judgments determines that the intermediate service process cannot read the target file, then the access file permission check of the intermediate service process is determined to have failed; otherwise, the access file permission check of the intermediate service process is determined to have passed.

4. The mandatory access control and protection method for network transmission files according to claim 1 is characterized in that: The receiver process permission level check includes: S301, the sending process packages a level request for obtaining the confidentiality level and integrity level of the receiving party into a data packet and sends it to the receiving party; S302, after the receiving party obtains the data packet of the confidentiality level and integrity level request sent by the sending party process, it obtains the confidentiality level and integrity level composition request reply packet data of the receiving party process for receiving the target file and returns it to the sending party process; S303, after the sending process obtains the request reply package data, it parses and obtains the confidentiality level and integrity level of the receiving process, and uses the security rules of the BLP security model to determine whether the receiving process can read the target file based on the confidentiality level of the receiving process and the target file, and uses the security rules of the BIBA security model to determine whether the receiving process can read the target file based on the integrity level of the receiving process and the target file. If any of the above two judgments determines that the receiving process cannot read the target file, the receiving process permission check is determined to have failed; otherwise, the receiving process permission check is determined to have passed.

5. The mandatory access control and protection method for network transmission files according to claim 1 is characterized in that: The receiving party storage directory permission and target file level check include: S401, the sender sends the file name of the target file, the corresponding storage directory in the system, and the confidentiality level and integrity level of the target file to the receiver; S402, after receiving the information sent by the sender, the receiver obtains the confidentiality level and integrity level of the receiver process and the storage directory; uses the security rules of the BLP security model to determine whether the receiver process can access the storage directory according to the confidentiality level of the receiver process and the storage directory, and uses the security rules of the BIBA security model to determine whether the receiver process can access the storage directory according to the integrity level of the receiver process and the target file; if any of the above two judgments determines that the receiver process cannot access the storage directory, then it is finally determined that the receiver process cannot access the storage directory, otherwise it is finally determined that the receiver process can access the storage directory; S403, the receiving party packages the final determination result into a data packet and sends it to the sending party; S404, the sender determines the receiver's storage directory permission and target file level check based on the permission determination result of whether the receiver process in the data packet packaged and sent by the receiver can access the storage directory. If the receiver process can access the storage directory, then it is determined that the receiver's storage directory permission and target file level check have passed; otherwise, it is determined that the receiver's storage directory permission and target file level check have failed.

6. The mandatory access control and protection method for network transmission files according to any one of claims 1 to 5, characterized in that: It also includes that when the sender and the receiver are interacting with each other, the validity of the message is verified by using the HMAC mechanism for the data to be transmitted: the sender generates a random number, calculates the sender's HMAC value by using the data to be transmitted, the preset key and the random number, and then packages the data to be transmitted, the random number and the sender's HMAC value into a data packet and sends it to the receiver; after receiving the data packet, the receiver calculates the receiver's HMAC value by using the received data, the preset key and the random number, and determines whether the sender's HMAC value and the receiver's HMAC value are consistent. If they are consistent, the received data is determined to be valid, otherwise the received data is determined to be invalid.

7. The mandatory access control and protection method for network transmission files according to claim 1 is characterized in that: The mandatory access mechanism is the selinux mandatory access mechanism. The sender uses the mandatory access mechanism to perform a series of access rights judgments before the recipient transfers the file. The receiver and the sender respectively enable the selinux mandatory access mode, the BLP security model and the BIBA security model. If any one fails to enable, the process ends and exits. Otherwise, continue to execute; after allowing the sender to transfer the target file to the receiver, the sender transmits the target file to the receiver, and the receiver receives the target file. The receiver sets the confidentiality level and integrity level of the corresponding file in the local storage directory according to the confidentiality level and integrity level of the target file sent by the sender, and completes the file transfer process.

8. A mandatory access control and protection system for network transmission files, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the mandatory access control and protection method for network transmission files as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the mandatory access control and protection method for network transmission files as described in any one of claims 1 to 7 through a processor.

10. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the mandatory access control and protection method for network transmission files as described in any one of claims 1 to 7 through a processor.

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