HP OpenVMS Systems Documentation

HP OpenVMS Programming Concepts Manual

Auditing is the recording of security-relevant activity as it occurs on a system. See the HP OpenVMS Guide to System Security for a list of all types of security-relevant activity or classes of events that are audited. The following table describes the security services that provide security auditing:

The system service SYS$AUDIT_EVENT is used to report security events to the auditing system. It examines the settings of the DCL command SET AUDIT to determine if an event is enabled for auditing. If the event is enabled for alarms or audits, SYS$AUDIT_EVENT generates an audit record and appends it to the system audit log file (or sends an alarm to a security operator terminal) that identifies the process involved and lists information supplied by its caller.

32.8 Checking Access Protection

The operating system provides two system services that allow a process to check access to objects on the system: SYS$CHKPRO and SYS$CHECK_ACCESS. The SYS$CHKPRO service performs the system access protection check on a user attempting direct access to an object on the system; SYS$CHECK_ACCESS performs a similar check on a third party attempting access to an object. The following table describes the security services that provide access checking:

The SYS$CHKPRO and SYS$CHECK_ACCESS system services have been extended to support auditing. The HP OpenVMS Guide to System Security describes how to use the auditing function. The HP OpenVMS System Services Reference Manual: A--GETUAI describes how to use the two system services. These services are described in the following sections.

32.8.1 Creating a Security Profile

The SYS$CREATE_USER_PROFILE system service returns a user profile, using information in the rights database and the system authorization database to generate the profile. The system services SYS$CHECK_ACCESS or SYS$CHKPRO accept as input the profile from SYS$CREATE_USER_PROFILE.

32.8.2 SYS$CHKPRO System Sevice

The SYS$CHKPRO system service invokes the access protection check used by the system. The service does not grant or deny access; rather, it performs the protection check. Subsequently, an application might grant or deny access to the specified object.

To pass the input and output information to SYS$CHKPRO, use the itmlst argument, which is the address of an item list of descriptors. The SYS$CHKPRO service compares the item list of the rights and privileges of the accessor to a list of the protection attributes of the object to be accessed. If the accessor can access the object, SYS$CHKPRO returns the status SS$_NORMAL; if the accessor cannot access the object, SYS$CHKPRO returns the status SS$_NOPRIV. The SYS$CHKPRO service does not grant or deny access. The subsystem itself must grant or deny access based on the output (SS$_NORMAL or SS$_NOPRIV) from SYS$CHKPRO.

The SYS$CHKPRO service also returns an item list of the rights or privileges that allowed the accessor access to the object, as well as the names of security alarms raised by the access attempt. For information about the item codes defined for SYS$CHKPRO, see the description of SYS$CHKPRO in the HP OpenVMS System Services Reference Manual.

See the HP OpenVMS Guide to System Security for a flowchart describing how SYS$CHKPRO evaluates an access request attempt.

32.8.3 SYS$CHECK_ACCESS System Service

The SYS$CHECK_ACCESS service performs a protection check on a third-party accessor. An example of this is a file server program that uses SYS$CHECK_ACCESS to ensure that an accessor (the third party) requesting a file has the required privileges to do so.

You pass the input and output information to SYS$CHECK_ACCESS by using the itmlst argument, which is the address of an item list of descriptors. You also pass the name of the accessor and the name and type of the object being accessed by using the usrnam, objnam, and objtyp arguments, respectively. The SYS$CHECK_ACCESS service compares the rights and privileges of the accessor to a list of the protection attributes of the object to be accessed. If the accessor can access the object, SYS$CHECK_ACCESS returns the status SS$_NORMAL; if the accessor cannot access the object, SYS$CHECK_ACCESS returns the status SS$_NOPRIV.

The SYS$CHECK_ACCESS service does not grant or deny access. The subsystem itself must explicitly grant or deny access based on the output (SS$_NORMAL or SS$_NOPRIV) from SYS$CHECK_ACCESS.

The SYS$CHECK_ACCESS service also returns an item list of the rights or privileges that allowed the accessor to access the object, as well as the names of security alarms raised by the access attempt. For information about the item codes defined for SYS$CHECK_ACCESS, see the description of SYS$CHECK_ACCESS in the HP OpenVMS System Services Reference Manual.

32.9 SYS$CHECK_PRIVILEGE

The SYS$CHECK_PRIVILEGE system service determines whether the caller has the specified privileges or identifiers. The service performs the privilege check and looks at the SET AUDIT settings to determine whether the system administrator enabled privilege auditing. When privilege auditing is enabled, SYS$CHECK_PRIVILEGE generates an audit record. The audit record identifies the process (subject) and privilege involved, provides the result of the privilege check, and lists supplemental event information supplied by its caller. Privilege audit records usually contain either the DCL command line or the system service name associated with the privilege check.

SYS$CHECK_PRIVILEGE completes asynchronously; that is, it does not wait for final status. For synchronous completion, use the SYS$CHECK_PRIVILEGEW service.

32.10 Implementing Site-Specific Security Policies

Occasionally, you may need to write routines that implement site-specific policies or special algorithms. The routines that you write can either replace or augment built-in operating system policies. This section contains instructions for replacing key operating system security routines with routines that are specific to your site. Two types of routines are discussed: loadable system services and shareable images.

32.10.1 Creating Loadable Security Services

This section describes how to create a system service image and how to update the SYS$LOADABLE_IMAGES:VMS$SYSTEM_IMAGES.DATA file, which controls site-specific loading of system images. These procedures update the loading of system images for all nodes of a cluster.

Currently, you can replace the following three system services with services specific to your site:

When you create the system service, you code the source module and define the vector offsets, the entry point, and the program sections for the system service. Then, you can assemble and link the module to create a loadable image.

Once you have created the loadable image, you install it. First, you copy the image into the SYS$LOADABLE_IMAGES directory and add an entry for it in the operating system's images file using the System Management utility (SYSMAN). Next, you invoke the system images command procedure to generate a new system image data file. Finally, you reboot the system to load your service.

The following sections describe how to create and load the the Get Security Erase Pattern (SYS$ERAPAT) system service.

You can find an example of the SYS$ERAPAT system service in SYS$EXAMPLES:DOD_ERAPAT.MAR on a VAX system. The description here also applies to the Hash Password (SYS$HASH_PASSWORD) and Magnetic Tape Accessibility (SYS$MTACCESS) system services. You can find an example of how to prepare and load the SYS$HASH_PASSWORD service in SYS$EXAMPLES:HASH_PASSWORD.MAR on a VAX system.

32.10.1.1 Preparing and Loading a System Service

With the following example, use this procedure to prepare and load a system service, in this case SYS$ERAPAT:

1. Create the source module.
   1. Include the following macro to define system service vector offsets:

      $SYSVECTORDEF ; Define system service vector offsets

   2. Use the following macro to define the system service entry point:

      SYSTEM_SERVICE ERAPAT, - ; Entry point name <R4>, - ; Register to save MODE=KERNEL,- ; Mode of system service NARG=3 ; Number of arguments

      
      (The code immediately following this macro is the first instruction of the SYS$ERAPAT system service.)
   3. Use the following macros to declare the desired program sections:

      DECLARE_PSECT EXEC$PAGED_CODE ; Pageable code PSCET DECLARE_PSECT EXEC$PAGED_DATA ; Pageable data PSECT DECLARE_PSECT EXEC$NONPAGED_DATA ; Nonpageable data PSECT DECLARE_PSECT EXEC$NONPAGED_CODE ; Nonpageable code PSCET

2. Assemble the source module by using the following command:

   $ MACRO DOD_ERAPAT+SYS$LIBRARY:LIB.MLB/LIB

3. Link the module to create a SYS$ERAPAT.EXE executive loaded image. You can link the module using the command procedure DOD_ERAPAT_LNK.COM in SYS$EXAMPLES on a VAX system. (A command procedure is also available to link the SYS$HASH_PASSWORD example.) To link the SYS$ERAPAT module, enter the following command:

   $ @SYS$EXAMPLES:DOD_ERAPAT_LNK.COM

4. Prepare the operating system image to be loaded.
   1. Copy the SYS$ERAPAT.EXE image produced by the link command into the SYS$COMMON:[SYS$LDR] directory. Note that privilege is required to put files into this directory.
   2. Add an entry for the SYS$ERAPAT.EXE image in the SYS$UPDATE:VMS$SYSTEM_IMAGES.IDX data file.
      You add an entry by using the SYSMAN command SYS_LOADABLE ADD. (See the HP OpenVMS System Management Utilities Reference Manual for a description of this command.) For example, the following commands add an entry in VMS$SYSTEM_IMAGES.IDX for SYS$ERAPAT.EXE:

      $ RUN SYS$SYSTEM:SYSMAN SYSMAN> SYS_LOADABLE ADD _LOCAL_ SYS$ERAPAT - _SYSMAN> /LOAD_STEP = SYSINIT - _SYSMAN> /SEVERITY = WARNING - _SYSMAN> /MESSAGE = "failure to load SYS$ERAPAT.EXE"

      
      This entry specifies that the SYS$ERAPAT.EXE image is to be loaded by the SYSINIT process during the bootstrap. If there is an error loading the image, the following messages are printed on the console terminal:

      %SYSINIT-E-failure to load SYS$ERAPAT.EXE -SYSINIT-E-error loading <SYS$LDR>SYS$ERAPAT.EXE, status = "status"

      
      The following table shows other error messages that may be returned:

      Message	Meaning	User Action
      NO_PHYSICAL_MEMORY	Physical memory is not available.	Check SYSGEN parameters.
      NO_POOL	Amount of nonpaged pool is insufficient.	Check SYSGEN parameters.
      MULTIPLE_ISDS	Encountered more than one image section of a given type.	Check link options.
      BAD_GSD	An inconsistency was detected.	Verify that the image was linked properly.
      NO_SUCH_IMAGE	The requested image cannot be located.	Check image name against images in SYS$LOADABLE_IMAGES.

   3. Invoke the SYS$UPDATE:VMS$SYSTEM_IMAGES.COM command procedure to generate a new system image data file (VMS$SYSTEM_IMAGES.DATA). The system bootstrap uses this image data file to load the appropriate images into the system.
   4. Reboot the system, which loads the original SYS$ERAPAT.EXE image into the system. Subsequent calls to the SYS$ERAPAT system service use the normal operating system routine.
      As the default, the system bootstrap loads all images described in VMS$SYSTEM_IMAGES.DATA. You can disable this feature by setting the special system parameter LOAD_SYS_IMAGES to 0.

With the following example, use this procedure to remove an executive loaded image; in this case, SYS$ERAPAT.EXE:

1. Enter the following SYSMAN command:

   SYSMAN> SYS_LOADABLE REMOVE _LOCAL_ SYS$ERAPAT

2. Invoke the SYS$UPDATE:VMS$SYSTEM_IMAGES.COM command procedure to generate a new system image data file (VMS$SYSTEM_IMAGES.DATA). The system bootstrap uses this image data file to load the appropriate images into the system.
3. Reboot the system, which loads the installation-specific SYS$ERAPAT.EXE image into the system. Subsequent calls to the SYS$ERAPAT system service use the installation-specific routine.
   As the default, the system bootstrap loads all images described in the system image data file (VMS$SYSTEM_IMAGES.DATA). You can disable this functionality by setting the special system parameter LOAD_SYS_IMAGES to 0.

A site security administrator can screen new passwords to make sure they comply with a site-specific password policy. (See the HP OpenVMS Guide to System Security for more information.) This section describes how a security administrator can encode the policy, create a shareable image and install it in SYS$LIBRARY, and enable the policy by setting a SYSGEN parameter.

Installing and enabling a site-specific password policy image requires both SYSPRV and CMKRNL privileges.

32.10.2.1 Creating a Shareable Image

To compile and link a shareable image that filters passwords for words that are sensitive to your site, perform the following steps:

1. Create the source module VMS$PASSWORD_POLICY.*.
   Bliss and Ada examples of the policy module's interface, called VMS$PASSWORD_POLICY.*, are located in SYS$EXAMPLES.
   Define two routine names in the source module: POLICY_PLAINTEXT and POLICY_HASH. These routines must be global (see your language reference for instructions on defining a global routine). The Set Password utility looks for these routine names and displays the message SYMNOTFOU either if the names are missing or if the routines are not defined as global.
2. Link the source file.
   For examples, use the VMS$PASSWORD_POLICY_LNK.COM command procedure, located in SYS$EXAMPLES on a VAX system.

To install a shareable image, perform the following steps:

1. Copy the file to SYS$LIBRARY and install it using the following commands:

   $ COPY VMS$PASSWORD_POLICY.EXE SYS$COMMON:[SYSLIB]/PROTECTION=(W:RE) $ INSTALL ADD SYS$LIBRARY:VMS$PASSWORD_POLICY/OPEN/HEAD/SHARE

2. Set the system parameter LOAD_PWD_POLICY to 1 as follows:

   $ RUN SYS$SYSTEM:SYSGEN SYSGEN> USE ACTIVE SYSGEN> SET LOAD_PWD_POLICY 1 SYSGEN> WRITE ACTIVE SYSGEN> WRITE CURRENT

3. To make the changes permanent, add the INSTALL command from step 1 to the SYS$SYSTEM:SYSTARTUP_VMS.COM file and modify the system parameter file, MODPARAMS.DAT, so that the LOAD_PWD_POLICY parameter is set to 1.
4. Run AUTOGEN as follows to ensure that the system parameters are set correctly on subsequent system startups:

   $ @SYS$UPDATE:AUTOGEN SAVPARAMS SETPARAMS

This chapter describes how to write a new Authentication and Credential Management (ACM) client program. An ACM client program uses the SYS$ACM[W] system service to do one or more of the following:

• Determine whether users are actually the individuals they claim to be.
• Acquire credentials¹ for a new user security context (persona).
• Change a user account password.

The Authentication and Credential Management (SYS$ACM[W]) service provides a standard programming interface for authentication, and can return credentials needed to enforce security policies of OpenVMS system logins. The SYS$ACM system service also provides a standard programming interface for user password management.

The SYS$ACM service might require the user, depending on the user name, to furnish two, one, or zero passwords. Other requirements might exist, such as supplying a code number from a "see-through" hardware token, or inserting a smart card into a reader. It is important that the program that calls SYS$ACM be relieved of the need to know all of these requirements, particularly because such a program might be used at multiple sites having different sets of rules.

Along with user authentication, the ACM service provides integrated credentials through normal and extended persona support. Normal persona support allows code to obtain native, that is, OpenVMS, process credentials, which contain username, UIC, and rights identifiers. Extended persona support also enables a process to obtain non-native credentials. As an example, this support would use both Windows NT credentials and OpenVMS credentials.

Use this chapter together with the description of the SYS$ACM[W] system service from the HP OpenVMS System Services Reference Manual: A--GETUAI. While this chapter presents a conceptual view, that manual contains the detailed formats and rules.

33.1 Identification, Authentication, and Authorization

When a user logs in to a system or runs an application that requires authentication, a dialogue takes place between that user and the system (or application). Policies may differ in some respects, but each requires the following basic functions of user identification, authentication, and authorization:

• Request user's user name.
• Request user's password.
• Verify user name and password.
• Check for expired passwords.
• Apply account restrictions.
• Issue credentials.
• Display system messages (optional).

An authentication policy is defined by a particular combination of user identification, authentication, and authorization attributes.

Policy attributes include the following:

• Identification syntax (simple user name, combination of domain/realm/principal-name)
• Authentication token mechanism (re-useable password, one-time password, system-generated password, single or dual password, challenge-response, hardware)
• Token re-use filters (password dictionary, password history, password legal character set, password minimum/maximum lengths, forced change schedule, expiration)
• Intrusion detection
• Case sensitivity
• Access restrictions (time-of-day, day-of-week, type of access)
• User account controls, such as account lock (disable) and account expiration
• Credential information (user and group identifiers, privileges, and so on)

Two authentication policies are presently supported: standard OpenVMS policy and external authentication with Microsoft distributed authentication policy.

33.2 ACME Subsystem Components

The Authentication and Credential Management Extensions (ACME) subsystem provides authentication and persona-based credential services. Applications can use these services to interact with the user to perform one or more of the following functions: user authentication, password change, and persona creation and modification. Both standard OpenVMS authentication and external authentication policies are supported, so applications use the same mechanisms as used by the system's LOGINOUT and SET PASSWORD components.

The ACME subsystem consists of the SYS$ACM system service, the ACME_SERVER process, one or more ACME (policy-provider) agents, and SET [SHOW] SERVER ACME configuration and management commands:

• SYS$ACM is a context-driven system service. The service is designed in such a way so that applications transparently adapt themselves to various authentication dialogues without requiring changes to the application. Applications call SYS$ACM to perform functions such as authenticate principal and change password. The service can return a complete security profile of the user in the form of a persona upon successful authentication.
• The ACME_SERVER process is a multithreaded server supporting one or more authentication policies. Each authentication policy is installed by configuring an ACME agent shareable image that "plugs in" to the ACME_SERVER process using a standard interface. The server manages the authentication sequence in an orderly fashion by calling each ACME agent in turn according to a defined sequence of phases. ACME agents are also responsible for adhering to certain rules regarding how agents can interact during an authentication sequence.
• ACME agents each define a single authentication policy that augments or replaces portions of the standard OpenVMS authentication policy. OpenVMS currently supports two ACME agents: an OpenVMS ACME agent (VMS) that provides the standard OpenVMS authentication policy, and a Microsoft ACME agent (MSV1_0) that provides external authentication using Microsoft distributed authentication protocol.
• The ACME subsystem is configured and managed using the DCL commands SET [SHOW] SERVER ACME.

With the introduction of the SYS$ACM[W] system service, operations that were formerly handled entirely within the LOGINOUT and SET PASSWORD programs are now distributed across multiple processes. The user interface activities remain in the original programs, as shown on the left side of Figure 33-1. Actual authentication calculations, however, have been moved to the ACME server process, as shown on the right side of that figure. The VMS ACME supports traditional authentication interactions for the VMS domain of interpretation (DOI). Other ACME agents may support additional DOIs or assist the VMS ACME, for example by providing stronger authentication.

Figure 33-1 SYS$ACM [W] Overview