CN116127477A - A system and method for program access control based on context awareness - Google Patents

Abstract

The invention discloses a program access control system and method based on context awareness, comprising the following steps: the access controller is used for controlling the resource access of the embedded equipment according to the execution result of the strategy executor and preventing unauthorized resource access requests; the policy executor is used for executing the policy returned by the policy interpreter; when the application program requests the resources of the embedded equipment, executing a corresponding strategy pre-configured in the current context information, and returning an execution result to the access controller to reject or grant the access request; the strategy interpreter is used for acquiring the strategy from the strategy database through the strategy engine and analyzing the strategy; and returning the strategy to a strategy executor; the policy engine is used for configuring the corresponding policies according to the context information and managing the policy database; a context engine for collecting context information by controlling sensors in the embedded device. The privacy data is protected, and the low-energy-consumption normal operation of the equipment is ensured.

Description

A system and method for program access control based on context awareness

technical field

The invention relates to the field of embedded operating systems, in particular to a context-aware-based program access control system and method.

Background technique

In recent years, embedded operating systems have gradually become more powerful and popular computing platforms. In embedded operating systems, there are many applications developed to provide new or enhanced services using resources on the operating system platform. Using permissions granted at installation, apps can access sensitive data and resources on the mobile device. Whether an application should gain privileges depends on a particular user context. Therefore, users need to consider the fine-grained resource usage control of context information, which is not supported by the inherent resource usage control mechanism of embedded operating systems. The permissions an application can access are determined at installation time and cannot be modified afterwards. Users can dynamically revoke or grant permissions to applications, but operating system platforms still do not support context-based adaptive access policies.

CareDroid et al. have done some research on context-aware computing for Android OS, mainly focusing on designing a context-aware adaptation engine for developers to facilitate their development. Furthermore, most work on OS context-aware usage control has focused on designing policy systems that do not restrict per-application permissions and are only valid system-wide. Others aim to enable users to configure access policies to applications contextually. However, these approaches have some limitations, such as not considering policy conflicts when multiple policies are available in a particular context. Furthermore, the above works require users to configure access policies, which ignores the premise that users traditionally have little domain knowledge about embedded operating system security and little knowledge about which application will bear what potential harm in a specific context. It can be difficult for users to identify suspicious or potentially malicious applications and configure policies appropriately without expert help.

Contents of the invention

In order to solve the above problems, the present invention provides a program access control system based on context awareness, including:

The access controller is used to control the resource access of the embedded device according to the execution result of the policy executor, and prevent unauthorized resource access requests;

The policy executor is used to execute the policy returned by the policy interpreter; when the application requests the resources of the embedded device, it executes the corresponding policy pre-configured in the current context information, and returns the execution result to the access controller to deny or grant access ask;

a policy interpreter, configured to obtain a policy from a policy database through a policy engine, and parse the policy; and return the policy to the policy executor;

Policy engine, used to configure corresponding policies according to the context information, and manage the policy database;

Context engine for gathering contextual information by controlling sensors in embedded devices.

Further, it also includes:

Fine-grained resource processor, used to process different types of resource access requests, and call different system services to obtain resources on the device according to authorized program requests;

Auxiliary tools are used to assist users to configure policies and guide users to manage policies.

Further, the policy executor, when executing multiple corresponding policies pre-configured in the current context, determines the policy to be executed among the multiple policies through the policy conflict arbiter according to the policy merging rules.

Further, the function of the policy interpreter further includes: when at least one policy is configured in the context, the policy interpreter returns available policies to the policy executor.

Further, the policy is used to limit the application program of the embedded device in a specific environment, including: policy constraints, location data and time data collection.

Further, the policy constraint is a group-free (s, o, a), s ∈ S, o ∈ O and a ∈ A, where S represents the subject set of the embedded device application, and O represents the embedded device A set of protected objects on resources, A means to authorize or request two operations.

Further, auxiliary tools are used to assist users in configuring policies and guide users in managing policies, including:

The user obtains the corresponding context environment information through the context manager in the auxiliary tool;

Users create policy constraints through the Constraint Manager in the Accessibility Tool.

Furthermore, the user obtains the corresponding context environment information through the context manager in the auxiliary tool, including:

Obtain the location and time data of the corresponding context, specifically, obtain the current time through the clock automatic synchronization function provided by the operating system of the embedded device, and obtain the latitude and longitude coordinates of the embedded device by using the satellite positioning in the energy controller.

Further, the user creates policy constraints through the constraint manager in the auxiliary tool, including:

Detecting applications in the embedded device through the malicious software detection engine of the constraint manager, identifying potential malicious applications, and notifying the user of the results;

According to the detection results, the user configures the corresponding resource access policy for the application in a specific context.

The present invention also provides a context-aware program access control method, including:

Acquiring context information in the embedded device; configuring a corresponding strategy according to the context information;

When the application program requests the resources of the embedded device, execute the corresponding policy pre-configured in the current context information, and obtain the execution result of denying or granting the access request;

The resource access request of the embedded device is received, and the resource access of the embedded device is controlled according to the execution result, so as to prevent unauthorized resource access requests.

Further, the policy is used to limit the application program of the embedded device in a specific environment, including: policy constraints, location data and time data collection.

The present invention also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method described in any one of the preceding claims are realized.

Through the context-aware program access control system and method provided by the present invention, the user configures policies through auxiliary tools in advance according to the privacy issues that need to be protected, and uses the control system to intercept resource usage requests of applications and check if in the current situation There are available policies, and then execute the available policies, deny or allow resource access requests according to the results of policy execution, protect private data and ensure the normal operation of devices with low energy consumption.

Description of drawings

FIG. 1 is a structural diagram of a context-aware based program access control system provided by an embodiment of the present invention;

Fig. 2 is a working flow chart of the policy configuration assistant tool involved in the embodiment of the present invention;

Fig. 3 is a relationship diagram of model policies, policy contexts and policy constraints involved in the embodiment of the present invention

Fig. 4 is a diagram of the power consumption test results involved in the embodiment of the present invention

Fig. 5 is a schematic flowchart of a context-aware based program access control method provided by an embodiment of the present invention.

Detailed ways

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described here, and those skilled in the art can make similar extensions without violating the connotation of the present invention, so the present invention is not limited by the specific implementations disclosed below.

Aiming at the problem of the embedded operating system program access resource control mechanism, the invention proposes a context-aware-based implementation method of the program access control system. Users configure policies through auxiliary tools in advance according to the privacy issues that need to be protected, and the usage control system intercepts application resource usage requests and checks if there is an available policy in the current situation. Available policies are then enforced, denying or allowing resource access requests based on the results of policy enforcement. Finally, the practicability and advancement of the system proposed in the present invention are verified by setting the modified power consumption of the device and the time overhead of the operating system.

The present invention provides a context-aware program access control system, the structure diagram of which is shown in Figure 1, including:

The access controller is used to control the resource access of the embedded device according to the execution result of the policy executor, and prevent unauthorized resource access requests;

The policy executor is used to execute the policy returned by the policy interpreter; when the application requests the resources of the embedded device, it executes the corresponding policy pre-configured in the current context information, and returns the execution result to the access controller to deny or grant access ask;

a policy interpreter, configured to obtain a policy from a policy database through a policy engine, and parse the policy; and return the policy to the policy executor;

Policy engine, used to configure corresponding policies according to the context information, and manage the policy database;

Context engine for gathering contextual information by controlling sensors in embedded devices.

The system further includes: a fine-grained resource processor, configured to process different types of resource access requests, and call different system services to obtain resources on the device according to authorized program requests;

Auxiliary tools are used to assist users to configure policies and guide users to manage policies.

As shown on the right side of Figure 1, there is a resource usage control mechanism in the embedded operating system. It simply denies or grants resource access requests to the application based on the permissions system, setting aside contextual information. To complement the permission-based access mechanism, contextual information is introduced. Seven core components are designed to achieve fine-grained context-aware resource usage control. The main components are shown on the left side of Figure 1.

An access controller, which controls access to embedded device resources and prevents unauthorized requests. While an embedded operating system provides a permission-based resource usage control mechanism that checks whether an application has the right to access the resource in question, an access controller complements the system with finer-grained control and context awareness. Access Controller enhances the protection of device privacy and security.

The policy executor is responsible for executing the policy returned by the policy interpreter. When an application requests a device's resources, it will execute the corresponding policy pre-configured in the current context, and then return the result to the access controller to deny or grant the access request. If more than one policy can be selected in a particular situation, the policy conflict arbiter is responsible for resolving it according to the policy combination rules. Policy merging rules define a process for determining which policy from a set of policies should be enforced.

The policy interpreter is designed to parse the policy obtained from the policy engine, and then compare the current context information obtained through the context engine with the pre-stored context in the policy. If at least one policy is configured in the current context, the interpreter returns the available policies to the policy executor.

The policy engine focuses on the management of the policy database. The policy engine provides users with an interface for creating policies, mainly referring to the policies corresponding to the context, and storing them in the policy database.

The context engine collects and provides context information through sensors in the device, and then assigns a logical name to each context so that the context information can be reused.

Fine-grained resource handlers are mainly focused on handling different kinds of resource access requests. It invokes different system services to obtain resources on the device based on specific authorized program requests.

Auxiliary tool is an application that helps users with little expertise to configure their strategies rationally. Assistive tools guide users step-by-step in managing (adding, updating, and deleting) policies. It also scans the apps installed on the device and finds potentially malicious apps, which makes it easy for users to find out which apps should be restricted in a particular context.

If users need to protect their privacy and device security, they can configure policies through auxiliary tools in advance, and the control system will intercept application resource usage requests and check if there is an available policy under the current situation. Available policies are then enforced, denying or allowing resource access requests based on the results of policy enforcement.

The policy is used to limit the application program of the embedded device in a specific environment, including: policy constraints, location data and time data collection. Policy restrictions represent constraints on application permissions when accessing protected resources and services. The context indicates when the restriction should be enforced. In order to obtain a structured description and a formatted representation, several definitions are introduced.

Define three basic sets: (1) S, which represents the subject set of the device application. (2) O, a set of protected objects representing resources on the device. (3) A, means to authorize or request two operations.

Since the package name and identity of each application must be unique in the operating system according to the permission protection mechanism, they are used to represent each specific application. The set S is composed of package names and identities of programs installed on the operating system, and "*" represents all installed applications. As shown in Table 1, for each resource object O in the collection, there is an associated action in the collection to protect these target objects in a specific context.

Table 1 Relationship between various resources of equipment and constraint actions

Definition 1 (policy constraints): s ∈ S, o ∈ O and a ∈ A. A policy constraint is defined as a tuple (s,o,a).

Two basic sets are defined: (1) LOC, which represents a set of location data for a specific location. (2) TIME, which represents a set of time data at a specific point in time. The set LOC is composed of satellite positioning coordinates (latitude and longitude). A point in time in the TIME collection is represented as:

TP=yy-MM-dd_HH:mm:ss, where yy∈{2021,2022,...}ΛMM∈{1,2,...,12}Λdd∈{1,2,...,31} ΛHH∈{0,1,...,23}Λmm, ss∈{0,1,...,59}

Definition 2 (policy context): It consists of location and time, c=(l, st, et), l∈LOC, st∈TIME, et∈TIME, st represents the start time point, and et represents the event end time point.

Definition 3 (Strategy): r is the policy constraint in Definition 1. c as the policy context in Definition 2. A policy is defined as a tuple (r,c). Figure 3 visually presents the strategy and the relationship between each component.

Policies are divided into two categories based on the type of resource being protected.

(1) Energy-based strategies

This category deals with strategies to limit the power wasted by applications.

(2) Privacy-based policies

This category pertains to policies that restrict an application's access to resources that could lead to privacy breaches. Privacy-based policies are further classified according to the type of objects in the restriction, as follows.

Permission-based policies: This category corresponds to the permissions of the embedded system itself, mainly restricting applications from accessing certain resources, such as collectors and meters.

Data-based policies: This category deals with user data stored on the device, such as active electrical energy, remaining power, etc.

Peripheral-based policies: This category pertains to the state of peripherals on the device, especially in the Settings application on the device.

Program Installation Based Policies: This category deals with policies that restrict the installation of applications.

Policy conflicts may exist when there are multiple policy alternatives in a certain context and these policies have different actions, such as some mutually exclusive or inclusive policies.

In order to resolve policy conflicts, four rules are used to allow users to choose when configuring policies in the access control mechanism system.

Deny takes precedence: If any restriction is a "deny" of more than one available policy, the result is "deny".

Authorize takes precedence: If any restriction is "authorize" for more than one available policy, the result is "authorize".

Majority first: The result depends on which limit gets more than half of the votes.

User First: Lists all available strategies and reminds the user to make a final decision.

Suppose there are two policies pi and pj, that is, p _i/j =(r _i/j ,c _/i ) _j , where ri _/j =(s _i/j ,o _/i,j a _/i ), c _i/j = (l _i/j , st _i/j , et _i/j ), r _i and r _j represent the policy constraints of policies pi and pj respectively, and ci and cj represent the policy contexts of policies pi and pj respectively. There are mainly four cases for the relationship between policies pi and pj, as shown in Table 2. Take the last scenario in the table as an example, if the policy contexts of policies pi and pj overlap, and the two have different policy constraint actions (one is to deny the use of resources by the application, and the other is to grant the use of resources) , then there is a conflict between strategies pi and pj at this time, and corresponding rules need to be designed to solve such problems.

Table 2 Interrelationships between device policies

Since users have little or no expertise in embedded system security, it is difficult to distinguish which applications are in a particular environment. Therefore, without the help of any professional, it is difficult for the user to configure a reasonable resource access policy to protect the resources in the device from being abused. In addition, it is also difficult for ordinary users to obtain context information and describe the context in a formal manner. The present invention designs and develops a policy configuration assistant tool to assist users in configuring policies. The workflow of the auxiliary tool is shown in Figure 2. The context manager in the auxiliary tool helps the user to obtain the corresponding context information (location and time) to indicate when and where the strategy will be executed in the future. At the same time, the user can also create policy constraints through the constraint manager component of the auxiliary tool to indicate the constraint actions that the application program should perform when applying for the use of various resources of the device. The main composition consists of the following two parts.

(1) Context manager. It is mainly responsible for the acquisition of context information such as location and time data. The current real time is obtained through the clock automatic synchronization function provided by the embedded operating system, and the longitude and latitude coordinates of the equipment are obtained by using the satellite positioning in the system of the energy controller.

(2) Constraint manager. A core component of Constraint Manager is the Malware Detection Engine.

Auxiliary tools can guide users step by step to acquire context and configure policies. At the same time, when configuring policy constraints, it can scan the applications installed on the device, detect the possibility that these applications are malicious software, and inform the user of the result. In this way, users can easily identify potential malicious applications, and configure corresponding resource access policies for applications in specific contexts, so as to achieve the purpose of protecting various resources of the device.

Based on the same inventive concept, the present invention also provides a context-aware program access control method, the process of which is shown in Figure 5, including:

Step S501, acquiring context information in the embedded device; configuring a corresponding strategy according to the context information;

Step S502, when the application program requests the resources of the embedded device, execute the corresponding policy pre-configured in the current context information, and obtain the execution result of denying or granting the access request;

Step S503, receiving the resource access request of the embedded device, and controlling the resource access of the embedded device according to the execution result, so as to prevent unauthorized resource access requests.

Further, the policy is used to limit the application program of the embedded device in a specific environment, including: policy constraints, location data and time data collection.

Application examples are as follows:

(1) Apply the modified embedded operating system to the energy controller to realize the resource usage control system, and evaluate the function of the resource access control mechanism by detecting the system energy consumption.

(2) To enforce energy-based and privacy-based policies, the corresponding methods on the embedded operating system are modified so that the embedded operating system can control the use of these resources. Evaluate the time overhead introduced by modifications to an embedded operating system to implement a resource usage control system.

In order to verify the effectiveness of a context-aware-based program access control mechanism implementation method of the present invention. In order to get reliable results, the system was tested in a real environment, a custom operating system was ported, and auxiliary tools were installed on the energy controller embedded operating system.

In the first experiment, modifications were applied to the operating system to implement a resource usage control system. The functionality of the system was then evaluated by porting the modified operating system into the energy controller. The power consumption is evaluated through three comparison tests: the power consumption under the original system; the power consumption under the customized embedded operating system; the power consumption under the customized embedded operating system when the power saving strategy is executed. Set the usage control system to check for device location updates every 60 seconds. In order to ensure that the three tests are all in the same environment, some business apps that are pre-installed with embedded operating systems are forced to frequently request hardware resources to run in the background. Figure 4 shows that compared with the original embedded OS and the modified embedded OS, the device power consumption ratio drops by about 7% per hour. Compared with the power consumption under the original system, the power consumption under the embedded operating system with the power saving strategy of the present invention saves about 10% per hour.

To enforce energy-based and privacy-based policies, the present invention modifies the corresponding methods on the embedded operating system to enable the embedded to control the use of these resources. Next, the time overhead introduced by modifications to the embedded operating system to implement a resource usage control system is evaluated. The time spent before and after the modification on the embedded was calculated to estimate the cost. Specifically, the overhead time required to control usage requests for permissions, data, system peripherals, application installations, and power was measured. As shown in the results in Table 3, the overall delay caused by the modification is imperceptible to the user.

Table 3 Time overhead caused by modification

Through the context-aware program access control system and method provided by the present invention, the user configures policies through auxiliary tools in advance according to the privacy issues that need to be protected, and uses the control system to intercept resource usage requests of applications and check if in the current situation There are available policies, and then execute the available policies, deny or allow resource access requests according to the results of policy execution, protect private data and ensure the normal operation of devices with low energy consumption.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be implemented. Modifications or equivalent replacements to the specific embodiments, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention, shall be covered by the scope of the claims of the present invention.

Claims (12)

1. A context-aware based program access control system, comprising:

the access controller is used for controlling the resource access of the embedded equipment according to the execution result of the strategy executor and preventing unauthorized resource access requests;

the policy executor is used for executing the policy returned by the policy interpreter; when the application program requests the resources of the embedded equipment, executing a corresponding strategy pre-configured in the current context information, and returning an execution result to the access controller to reject or grant the access request;

the strategy interpreter is used for acquiring strategies from the strategy database through the strategy engine and analyzing the strategies; and returning the strategy to a strategy executor;

the policy engine is used for configuring the corresponding policies according to the context information and managing the policy database;

a context engine for collecting context information by controlling sensors in the embedded device.

2. The system of claim 1, further comprising:

the fine-grained resource processor is used for processing different kinds of resource access requests, and calling different system services according to authorized program requests to acquire resources on the equipment;

and the auxiliary tool is used for assisting the user in configuring the strategy and guiding the user to manage the strategy.

3. The system of claim 1, wherein the policy enforcer, when enforcing the plurality of pre-configured corresponding policies in the current context, determines, by the policy conflict arbiter, the policy to be enforced among the plurality of policies based on the policy merge rule.

4. The system of claim 1, wherein the function of the policy interpreter further comprises: when at least one policy is configured in the context, the policy interpreter returns the available policies to the policy enforcer.

5. The system of claim 1, wherein the policy for limiting application to embedded device applications in a particular environment comprises: policy constraints, location data, and a set of time data.

6. The system of claim 5, wherein the policy constraint is a no group (S, O, a), S e S, O e O and a e a, where S represents a set of principals for the embedded device application, O represents a set of protected objects for a resource on the embedded device, and a represents authorizing or requesting two operations.

7. The system of claim 2, wherein the auxiliary tool for assisting the user in configuring the policy and guiding the user in managing the policy comprises:

the user obtains corresponding context environment information through a context manager in the auxiliary tool;

the user creates policy constraints through a constraint manager in the auxiliary tool.

8. The system of claim 7, wherein the user obtains the corresponding context environmental information via a context manager in the auxiliary tool, comprising:

the method comprises the steps of obtaining position and time data of corresponding contexts, specifically obtaining current time through a clock automatic synchronization function provided by an operating system of the embedded equipment, and obtaining longitude and latitude coordinates of the embedded equipment by utilizing satellite positioning in an energy controller.

9. The system of claim 7, wherein the user creates the policy constraint through a constraint manager in the auxiliary tool, comprising:

detecting an application program in the embedded equipment through a malicious software detection engine of the constraint manager, identifying a potential malicious application program, and informing a user of the result;

and the user configures a corresponding resource access strategy for the application program in the specific context according to the detection result.

10. A program access control method based on context awareness, comprising:

acquiring context information in the embedded equipment; configuring a corresponding strategy according to the context information;

when an application program requests the resources of the embedded equipment, executing a corresponding strategy pre-configured in the current context information, and acquiring an execution result of refusing or granting the access request;

and receiving a resource access request of the embedded equipment, and controlling the resource access of the embedded equipment according to the execution result to prevent unauthorized resource access requests.

11. The method of claim 10, wherein the policy for limiting application to embedded device applications in a particular environment comprises: policy constraints, location data, and a set of time data.

12. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 10 to 11.

Images