Method for executing an application in a restricted operating environment

A user is presented with one or more user-level permissions in a human understandable language, where the one or more user-level permissions represent one or more application-level permissions requested from an application for accessing one or more resources. A security profile is generated having one or more operating system (OS)-level permissions based on at least one of the user-level permissions authorized by the user. The security profile is enforced to restrict the application to accessing the one or more resources based on the OS-level permissions.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to the field of secure computing. More particularly, embodiments of the invention relate to configuring an application to be executed in a restricted operating environment.

BACKGROUND

Security concerns for all types of processor-based electronic devices, and particularly for computing devices, have become a significant concern. While some concerns may relate to detrimental actions which may be undertaken by defective code implemented by such devices, the greater concerns relate to the ramifications of various types of attacks made upon such devices through malicious code, including code conventionally known in the field by a number of names, including “viruses”, “worms”, “Trojan horses”, “spyware”, “adware”, and others. Such malicious code can have effects ranging from relatively benign, such as displaying messages on a screen, or taking control of limited functions of a device; to highly destructive, such as taking complete control of a device, running processes, transmitting and/or deleting files, etc. Virtually any type of imaginable action on a processor-based device has been the subject of attacks by malicious code.

Many of these attacks are directed at computing devices, such as workstations, servers, desktop computers, notebook and handheld computers, and other similar devices. Many of these computing devices can run one or more application programs which a user may operate to perform a set of desired functions. However, such attacks are not limited to such computing devices. A broader group of various types of devices, such as cell phones; personal digital assistants (“PDA's”); music and video players; network routers, switches or bridges; and other devices utilizing a microprocessor, microcontroller, or a digital signal processor, to execute coded instructions have been the subjects of attacks by malicious code.

A number of methodologies have been used in an attempt to reduce or eliminate both the attacks and influence of malicious or defective code. Generally, these methodologies include detection, prevention, and mitigation. Specifically, these methodologies range from attempts to scan, identify, isolate, and possibly delete malicious code before it is introduced to the system or before it does harm (such as is the objective of anti-virus software, and the like), to restricting or containing the actions which may be taken by processes affected by malicious or defective code.

When an application is to be executed, a user may be prompted whether the execution of the application should be allowed or denied entirely. There is a lack of efficient way to configure in a finer-grained fashion whether a particular action to be performed by the application is allowed. In addition, a permission to allow an application to perform a particular action is typically configured at a low level such as an operating system (OS) level that is not human understandable. There has been a lack of mechanism to convey permission information to a user at a higher level that is human understandable.

DETAILED DESCRIPTION

According to some embodiments, a mechanism is provided to help a user to conveniently select what permissions the user wishes to grant to executable code such as an application, an applet, or an application plugin. Permissions requested by an application (also referred to as application-level permissions) are translated into higher level human understandable user-level permissions. The user-level permissions are presented to the user as one or more permission blocks, where a permission block is a high level concept which enables a user-comprehensible function, such as the ability to print a document, open a document, etc. Permission blocks are made up of OS-level permissions that are needed to provide the user functionality (e.g., read access on a directory, on a file, etc.)

When the application is to be launched, or a plug-in is to be loaded, a request for permissions is made by the appropriate loader, and the user is notified of user-level permissions representing the requested application-level permissions. In response to user inputs representing authorization to grant or deny some or all of the presented user-level permissions, OS-level permissions are generated based on the granted user-level permissions. A security profile is generated based on the granted OS-level permissions and the security profile is enforced during execution of the application to restrict the application accessing resources permitted by the OS-level permissions of the security profile. As a result, the user is presented with useful and understandable information concerning what permissions have been granted to the application without having to understand the application-level and/or OS-level permissions.

FIG. 1is a block diagram illustrating a system for restricting an application in a restricted operating environment according to one embodiment of the invention. System100can represent any of computing device or system, such as a desktop, laptop, server, tablet, personal digital assistant (PDA), mobile phone, set-top box, media player, or gaming device, etc. Referring toFIG. 1, system100includes application101communicatively coupled to security framework103via application programming interface (API)102. Note that although one application as a client is shown, for illustration purpose only, more clients may also be coupled to security framework103. In one embodiment, security framework103may be implemented as a system component of an operating system, which may be any kind of operating systems, such as iOS™ or Mac OS X™ from Apple Inc. of Cupertino, Calif., a Windows™ operating system from Microsoft Corporation of Redmond, Wash., or alternatively a LINUX or UNIX operating system. For example, security framework103may be implemented as part of a sandbox management unit running within a kernel of the operating system, where the sandbox management unit is configured to restrict an application to be executed within a restricted operating environment, for example, based on a security profile associated with the application. An application is only entitled to access a resource that is implicitly allowed, explicitly granted, or otherwise specified in the security profile of the application.

API102may be implemented as a system API to allow any of client applications such as application101to communicate with security framework103. Application101can be any kind of application such as a standalone application. Alternatively, application101may be a plug-in application or applet that is hosted within another application. For example, application101may be a Java™ applet embedded within a Web page hosted or processed by a browser application, where the Web page may be downloaded from a variety of information or service provider servers such as Web servers. In this example, a Java applet communicates with the browser application via a corresponding agent or plug-in (e.g., Java plug-in), where the browser application communicates with security framework103via a system API (e.g., API102). Some applets may include photo uploaders and picture takers, interactive maps that show a user's real-time location, or collaborative document editors.

In one embodiment, application101includes information describing one or more permissions requested and/or required by application101, referred to herein as application-level permissions107. Application-level permissions107refer to the permissions requested by application101for accessing one or more resources of system100during execution of application101. Application-level permissions107may be specified by a developer or administrator of application101. Application-level permissions107are typically specified in a format that is compatible with the API102in a programming language of application101. Application-level permissions107may or may not be described in a human understandable manner.

In one embodiment, application-level permissions107include a first portion of one or more permissions that are required by application101and a second portion of one or more permissions that are optionally required by application101during execution of application101. That is, the required permissions represent the permissions an application needs in order to perform its basic functions. An example of such a required permission for an application such as a photo editor application includes a permission to access files in the user's home directory on the file system. The optional permissions represent those permissions the application would benefit from having, but whose absence will still allow the application to perform its basic functions. An example of such an optional permission is a permission to print a picture. As another example, an instant messaging application would require access to connect over a network to an instant messaging server, but would optionally request access to the system's microphone and camera.

In one embodiment, application-level permissions107may be embedded within the source code of an application or as metadata of the application.FIG. 3is an example of a hypertext mark-up language (HTML) script representing a Web-based application such as a Java applet. Script300includes a security tab301having zero or more required permissions302and zero or more optional permissions303requested by application303. Permissions302-303may be specified or programmed by a developer of application300. Note that the format as shown inFIG. 3is described in view of an HTML application. The formats may be different for other types of programming languages.

Referring back toFIG. 1, according to one embodiment, when application101is to be loaded, an application loader that is responsible for loading application101(not shown) is configured to extract metadata representing application-level permissions107from application101, including determining the required application-level permissions and optional application-level permissions requested by application101. As described above, application101can be a standalone application which may be loaded by an application loader of an operating system. Alternatively, application101can be an applet (e.g., Java applet) hosted by a hosting application (e.g., browser). In this situation, a plug-in of the hosting application is responsible for loading application101.

In one embodiment, prior to loading application101, the application loader is configured to determine whether the requested permissions are to be granted by the system. Application101may only be loaded if at least the required application-level permissions are granted. In one embodiment, in response to a request to load application101, the application loader is configured to extract and transmit application-level permissions107to security framework103via API102. Based on application-level permissions107, permission mapping module110is configured to map the application-level permissions to user-level permissions using permission mapping table105. The mapped user-level permissions are then presented to a user via user interface111, including zero or more required user-level permissions112and zero or more optional user-level permissions113. In one embodiment, the user-level permissions are described in human or user understandable language, images, iconography, or other representation such that when presented to a user, the user can easily understand what permissions are being sought by the application, without having to understand the low level application-level permissions and/or OS-level permissions used by the application developers or the operating system.

FIG. 2is a diagram illustrating an example of a permission mapping data structure according to one embodiment of the invention. Referring toFIG. 2, permission mapping data structure105includes user-level permissions201, application-level permissions202, and OS-level permission203, which may be defined according to a set of rules or definitions. The mapping of different permissions201-203can be implemented in a variety of ways. According to one embodiment, for each of application-level permissions202, data structure105is maintained in a manner that one can search and find one or more corresponding user-level permissions from user-level permissions201and one or more corresponding OS-level permissions from OS-level permissions203, or vice versa.

As can be shown, user-level permissions201are described using certain user understandable terms, language, or other expression, while OS-level permissions203may be described in lower level terms (e.g., machine or OS understandable terms) that an ordinary user would have a hard time understanding. Application-level permissions202may be specified in a manner dependent upon the specific API and application programming languages. Thus, the formats or terms used in application-level permissions may be different for different APIs and programming languages. In one embodiment, different APIs or programming languages may use different permission mapping tables or data structures.

Referring back toFIG. 1, according to one embodiment, based on application-level permissions107requested by application101, permission mapping module110is configured to convert the application-level permissions to user-level permissions using permission mapping table105and present the user-level permissions to a user via user interface111for user authorization. The presented user-level permissions include required user-level permissions112and optional user-level permissions113. From user interface111, a user can grant or deny some or all of the requested permissions.

FIG. 4is a block diagram illustrating an example of a graphical user interface (GUI) according to one embodiment of the invention. For example, GUI400may be presented as part of user interface111ofFIG. 1. Referring toFIG. 4, GUI400presented to a user includes zero or more required user-level permissions401and zero or more optional user-level permissions402-403. User-level permissions401-403may be converted or mapped from application-level permissions specified by an application to be loaded (e.g., application-level permissions302-303ofFIG. 3based on mapping table105ofFIG. 2). In this example, the user-level permission of “read your pictures” may be converted from an application-level permission of “r˜/pictures” based on mapping table105ofFIG. 2. Similarly, the user-level permission of “use your camera” may be converted from an application-level permission of “r/w camera” based on mapping table105ofFIG. 2. As a result, an ordinary user can easily understand the permissions of “read your pictures” and “use your camera” rather than “r˜/pictures” and “r/w camera.”

Note that permissions402-403are optional permissions and that without them, the application can still perform its basic functions. A user can optionally grant or deny any of permissions402-403via the associated checkboxes, and the application can still function with or without the optional features or functions permitted by optional permissions402-403. However, if the user denies required permission401, for example, by clicking the “cancel” button, the application may not function and may be prevented from loading.

According to one embodiment, once the permissions401-403have been configured and the user positively confirms the granting of the permissions, for example, by clicking the “OK” button, a security profile is dynamically generated. The security profile includes at least the granted permissions listed in OS-level permissions, which are translated or converted from user-level permissions401-403. The security profile may also include permissions implicitly granted by the operating system or security manager. The security profile is then used by the OS or a security manager (e.g., sandbox manager) to enforce the permissions set forth in the security profile to limit the associated application operating in a restricted operating environment.

The security profile may be loaded in a system memory (e.g., random-access memory or RAM) and used by the OS. Thus, the security is generated and temporarily loaded for the current instance of the application. Once the application is unloaded, the security profile may be unloaded or erased from the memory. When the same application is loaded again at a future time, the above processes may be performed again and a new profile may be generated for the new instance of the application.

According to one embodiment, an option404is provided to allow a user to specify whether the security profile should be saved to a persistent storage location such as a hard drive of the system. The security profile may be stored in an encrypted form or be invisible to the user. If the user enables the option404, the security profile is stored in a persistent storage location. In this situation, the security framework also maintains a database or table indicating which profile is associated with each application. An application may be identified based on a variety of identifiers or indicators.

Subsequently, when an application is about to be loaded an identifier of the application is used to determine whether a security profile has been previously created and stored in a persistent storage. Several mechanisms can be used to identify the application, including its name, a programmatic identifier inside it's binary or bundle, a code-signing certificate chain used to sign the application, or other criteria. If a previous security profile has been identified, permissions currently requested by the application and the permissions previously granted are compared to determine whether the same or greater requested permissions have been previously granted to the same application. Note that a security profile may include information identifying the permissions previously requested and permissions previously granted.

If the currently requested permissions are different than the previously requested permissions, according to one embodiment, a GUI page such as the one as shown inFIG. 4may be displayed requesting a user to confirm the authorization of the new permissions requested. In addition, according to one embodiment, if certain optional permissions were previously requested, the GUI page may still be displayed to confirm whether the user wishes to grant the optional permissions this time around. In some situations, a user may have granted an optional permission during a previous execution of the application, but the user may not want to grant the same optional permission in a subsequent execution of the application. The new settings may be updated in the security profile dependent upon whether the user indicates that the new settings should be saved in a persistent security profile. Furthermore, the security profile may be removed or erased from the persistent storage if the user denies all the permissions requested.

FIG. 5is a flow diagram illustrating a method for granting permissions of an application according to one embodiment of the invention. Method500may be performed by security framework103ofFIG. 1. Referring toFIG. 5, at block501, one or more application-level permissions are received which are requested by an application for accessing one or more resources. At block502, user-level permissions corresponding to the application-level permissions are presented to a user, where the user-level permissions are presented in a user understandable language or manner. For example, the user-level permissions may be presented using a GUI page similar to the one as shown inFIG. 4. The user-level permissions may be converted from the application-level permissions using a permission mapping table that maps application-level permissions to user-level permissions and OS-level permissions. At block503, a security profile is generated based on the user inputs, where the security profile includes zero or more OS-level permissions generated from zero or more user-level permissions granted by the user. Similarly, the OS-level permissions may be converted from the user-level permissions using the permission mapping table. At block504, the security profile is enforced to restrict the application accessing the resources. The security profile may also be cached in a persistent storage.

FIG. 6is a flow diagram illustrating a method for granting permissions of an application according to another embodiment of the invention. Method600may be performed by security framework103ofFIG. 1. Referring toFIG. 6, in response to a request to load an application, at block601, metadata is extracted from the application to determine zero or more permissions requested by the application for accessing zero or more resources. The metadata includes information identifying application-level permissions requested. At block602, the requested permissions are presented to a user, including a set of zero or more required permissions, and a second set of zero or more optional permissions. The requested permissions are presented to the user via a GUI page similar to the one as shown inFIG. 4. The permissions are presented as user-level permissions converted from the application-level permissions using a permission mapping table. The permission mapping table maps an application-level permission to one or more user-level permissions and one or more OS-level permissions, or vice versa. At block603, a security profile is generated based on the user's response granting all of the required permissions, as well as none, some, or all of the optional permissions. The security profile includes information identifying one or more OS-level permissions that are converted from the presented user-level permissions using the permission mapping table. At block604, the security profile is enforced to restrict the application accessing the one or more resources based on the granted permissions.

FIG. 7is a flow diagram illustrating a method for granting permissions of an application according to another embodiment of the invention. Method700may be performed by security framework103ofFIG. 1. Referring toFIG. 7, in response to a request to load an application, at block701, metadata is extracted from the application to determine zero or more permissions requested by the application for accessing zero or more resources. Resources may represent a file, a directory, an email, a network connection, a peripheral device, a GUI or window, an interface device, etc. At block702, it is determined whether the requested permissions have been previously granted during a previous execution of the application. Such a determination may be performed by comparing the requested permissions with permissions listed in a security profile associated with the application. The security profile may have been created and stored in a persistent storage during a previous execution of the application.

If the request permissions have been previously granted based on the security profile, at block705, the same permissions are enforced based on the security profile during execution of the current instance of the application, without a need to prompt a user for authorizing the requested permissions. If the requested permissions have not been previously granted (e.g., the currently requested permission(s) are not listed in the security profile or listed but not granted in the security profile), at block703, the requested permissions are presented to a user for authorization, for example, using a permission mapping module such as that illustrated in block110inFIG. 1, and GUI similar to the one as shown inFIG. 4. At block704, a new security profile is generated based on the user input. Alternatively, an existing security profile may be updated based on the user input. At block705, the security profile is enforced.

FIG. 8is a block diagram of a data processing system, which may be used with one embodiment of the invention. For example, the system800may be used as part of system100as shown inFIG. 1. Note that whileFIG. 8illustrates various components of a computer system, it is not intended to represent any particular architecture or manner of interconnecting the components; as such details are not germane to the present invention. It will also be appreciated that network computers, handheld computers, cell phones and other data processing systems which have fewer components or perhaps more components may also be used with the present invention. The computer system ofFIG. 8may, for example, be an Apple Macintosh computer or MacBook, an IBM compatible PC, a device such as an iPhone or iPad, or a computer server.

As shown inFIG. 8, the computer system800, which is a form of a data processing system, includes a bus or interconnect802which is coupled to one or more microprocessors803and a ROM807, a volatile RAM805, and a non-volatile memory806. The microprocessor803is coupled to cache memory804. The bus802interconnects these various components together and also interconnects these components803,807,805, and806to a display controller and display device808, as well as to input/output (I/O) devices810, which may be mice, keyboards, modems, network interfaces, printers, and other devices which are well-known in the art.

Typically, the input/output devices810are coupled to the system through input/output controllers809. The volatile RAM805is typically implemented as dynamic RAM (DRAM) which requires power continuously in order to refresh or maintain the data in the memory. The non-volatile memory806is typically a magnetic hard drive, a magnetic optical drive, an optical drive, or a DVD RAM or other type of memory system which maintains data even after power is removed from the system. Typically, the non-volatile memory will also be a random access memory, although this is not required.

WhileFIG. 8shows that the non-volatile memory is a local device coupled directly to the rest of the components in the data processing system, the present invention may utilize a non-volatile memory which is remote from the system; such as, a network storage device which is coupled to the data processing system through a network interface such as a modem or Ethernet interface. The bus802may include one or more buses connected to each other through various bridges, controllers, and/or adapters, as is well-known in the art. In one embodiment, the I/O controller809includes a USB (Universal Serial Bus) adapter for controlling USB peripherals. Alternatively, I/O controller809may include an IEEE-1394 adapter, also known as FireWire adapter, for controlling FireWire devices.