$GET SECURITY

$GET_SECURITY is a system service that retrieves the security characteristics of an object: protection code, the owner, and the access control list (ACL). The security management services, $GET_SECURITY and $SET_SECURITY, maintain a single master copy of a profile for every security object in an OpenVMS Cluster environment. They also ensure that only one process at a time can modify an object’s security profile.

There are different ways of identifying which protected object $GET_SECURITY should process:

• Whenever the contxt argument has a nonzero value, $GET_SECURITY uses the context to select the object and ignores the class name, object name, and object handle.
• With some types of objects, such as a file or a device, it is possible to select an object on the basis of its objhan and clsnam values.
• If neither a nonzero contxt argument nor an objhan argument is provided, $GET_SECURITY uses an object’s class name (clsnam) and object name (objnam) to select the object.

When you call $GET_SECURITY, the service selects the specified protected object and fetches a local copy of the object’s security profile. The context for a security management operation can be established through either $GET_SECURITY or $SET_SECURITY. Whenever the context is set by one service, the other service can use it, provided the necessary locks are being held. If you intend to modify the profile, you must set the write lock flag (OSS$M_WLOCK) when you establish the context. There are many situations in which the contxt argument is essential. By establishing a context for an ACL operation, for example, a caller can retain an ACL position across calls to $GET_SECURITY so that a set of ACEs can be read and modified sequentially. A security context is released by a call to $SET_SECURITY or $GET_SECURITY that sets the OSS$M_RELCTX flag. Once the context is released, the user-supplied context longword is set to 0.

Format

SYS$GET_SECURITY [clsnam],[objnam],[objhan],[flags],[itmlst],[contxt],[acmode]

C prototype:

int sys$get_security (void *clsnam, void *objnam, unsigned int *objhan, unsigned int
                      flags, void *itmlst, unsigned int *contxt, unsigned int *acmode);

Arguments

clsnam

OpenVMS usage:	char_string
Type:	character-coded text string
Access:	read only
Mechanism:	by descriptor

Name of the object class. The clsnam argument is the address of a descriptor pointing to a string containing the name of the object class. The following is a list of protected object class names:

• CAPABILITY
• COMMON_EVENT_CLUSTER
• DEVICE
• FILE
• GLXSYS_GLOBAL_SECTION
• GLXGRP_GLOBAL_SECTION
• GROUP_GLOBAL_SECTION
• ICC_ASSOCIATION
• LOGICAL_NAME_TABLE
• QUEUE
• RESOURCE_DOMAIN
• SECURITY_CLASS
• SYSTEM_GLOBAL_SECTION
• VOLUME

objnam

OpenVMS usage:	char_string
Type:	character-coded text string
Access:	read only
Mechanism:	by descriptor

Name of the protected object whose associated security profile is going to be retrieved. The objnam argument is the address of a descriptor pointing to a string containing the name of the protected object. The format of an object name is class specific. The following table lists object names and describes their formats:

Object Class	Object Name Format
CAPABILITY	A character string. Currently, the only capability object is VECTOR.
COMMON_EVENT_CLUSTER	Name of the event flag cluster, as defined in the Associate Common Event Flag Cluster ($ASCEFC) system service.
DEVICE	Standard device name
FILE	Standard file specification
GROUP_GLOBAL_SECTION	Section name, as defined in the Create and Map Section ($CRMPSC) system service
ICC_ASSOCIATION	ICC security object name node::association_name. The special node name, ICC$::, refers to entries in the clusterwide registry. For registry entries, the Access Access Type does not apply.
LOGICAL_NAME_TABLE	Table name, as defined in the Create Logical Name Table ($CRELNT) system service.
QUEUE	Standard queue name, as described in the Send to Job Controller ($SNDJBC) system service.
RESOURCE_DOMAIN	An identifier or octal string enclosed in brackets
SECURITY_CLASS	Any class name shown in column 1, or a class name followed by a period (.) and the template name. Use the DCL command SHOW SECURITY to display possible template names.
SYSTEM_GLOBAL_SECTION	Section name, as defined in the Create and Map Section ($CRMPSC) system service.
VOLUME	Volume name or name of the device on which the volume is mounted.

objhan

OpenVMS usage:	object_handle
Type:	longword(unsigned)
Access:	read only
Mechanism:	by reference

Data structure identifying the object whose associated characteristics are going to be retrieved. The objhan argument is an address of a longword containing the object handle. You can use the objhan argument as an alternative to the objnam argument; for example, channel number clearly specifies the file open on the channel and can serve as an object handle. The following table shows the format of the object classes:

Object Class	Object Handle Format
COMMON_EVENT_CLUSTER	Event flag number
DEVICE	Channel number
FILE	Channel number
RESOURCE_DOMAIN	Resource domain identifier
VOLUME	Channel number

flags

OpenVMS usage:	flags
Type:	mask_longword
Access:	read only
Mechanism:	by value

Mask specifying processing options. The flags argument is a longword bit vector wherein a bit, when set, specifies the processing option. The flags argument requires the contxt argument. The following table describes each flag:

Symbolic Name	Description
OSS$M_RELCTX	Release the context structure at the completion of this request
OSS$M_WLOCK	Maintain a write lock on the security profile at the completion of this request. $GET_SECURITY ignores the flag if the context has already been established.

These symbolic names are defined in the $OSSDEF macro. You construct the flags argument by specifying the symbolic names of each flag.

itmlst

OpenVMS usage:	item_list_3
Type:	longword (unsigned)
Access:	read only
Mechanism:	by reference

Item list specifying which information about the process or processes is to be returned. The itmlst argument is the address of a list of item descriptors, each of which describes an item of information. The list of item descriptors is terminated by a longword of 0.

With the item list, the user retrieves the protected object’s characteristics. The user defines which security characteristics to retrieve. If this argument is not present, only the flags argument is processed. Without the itmlst argument, you can only manipulate the security profile lock or release contxt resources.

The following table describes the item descriptor fields:

Descriptor Field	Definition
Buffer length	A word containing an integer specifying the length (in bytes) of the buffer in which $GET_SECURITY is to write the information. The length of the buffer needed depends on the item code specified in the item code field of the item descriptor. If the value of buffer length is too small, $GET_SECURITY truncates the data.
Item code	A word containing a symbolic code specifying the item of information that $GET_SECURITY is to return. The $OSSDEF macro defines these codes. A description of each item code is given in the Item Codes section.
Buffer address	A longword containing the address of the buffer in which $GET_SECURITY is to write the information
Return length address	A longword containing the address of a word in which $GET_SECURITY writes the length (in bytes) of the information it actually returns.

Item Codes

The following table provides a summary of item codes that are valid in an item descriptor in the itmlst argument.

Item Identifier	Description
OSS$_ACCESS_NAMES	Returns the access name translation table in the buffer pointed to by the buffer address field of the item descriptor. The access name translation table is a 32-quadword vector followed by a variable section containing the access names. Each bit in the vector represents a single access type. The contents of the quadword is a string descriptor that corresponds to the ASCII bitname string. Undefined access types have zero-length names. The return length, if present, returns the length of the table.
OSS$_ACCESS_NAMES_LENGTH	Returns the size (in bytes) of the access bitname translation table.
OSS$_ACL_FIND_ENTRY	Locates an ACE pointed to by the buffer address. OSS$_ACL_FIND_ENTRY sets the position within the ACL for succeeding ACL operations; for example, for a deletion or modification of the ACE. If the buffer address is 0, it returns SS$_ACCVIO.
OSS$_ACL_FIND_NEXT	Advances the current position to the next ACE in the ACL.
OSS$_ACL_FIND_TYPE	Returns an ACE of a particular type if there is one in the buffer pointed to by the buffer address. OSS$_ACL_FIND_TYPE sets the position within the ACL for succeeding ACL operations. If the buffer address is 0, it returns SS$_ACCVIO.
OSS$_ACL_GRANT_ACE	Returns the ACE in the object’s ACL that grants or denies the user access to that object. OSS$_ACL_GRANT_ACE returns the ACE found in the buffer pointed to by the buffer address.
OSS$_ACL_LENGTH	Returns the size (in bytes) of the object’s ACL. The buffer address field points to a longword that receives the size.
OSS$_ACL_POSITION_BOTTOM	Sets the ACL position to point to the bottom of the ACL.
OSS$_ACL_POSITION_TOP	Sets the ACL position to point to the top of the ACL.
OSS$_ACL_READ	Returns the portion of the object’s ACL to the buffer pointed to by the buffer address.
OSS$_ACL_READ_ENTRY	Reads the ACE pointed to by the buffer address.
OSS$_CLASS_NAME	Returns the full object class name.
OSS$_FIRST_TEMPLATE	Returns the name of the first template profile for the object named in the objnam argument. This item code is valid only for security class objects. If the clsnam is not Security_Class, SS$_INVCLSITM is returned.
OSS$_NEXT_OBJECT	Returns the name of the next object. A return length of 0 indicates the end of the list. This item code is valid only for security class objects. If the clsnam is not Security_Class, SS$_INVCLSITM is returned.
OSS$_NEXT_TEMPLATE	Returns the name of the next template. This item code allows you to step through a list of an object’s templates. A return length of 0 indicates the end of the list. This item code is valid only for security class objects. If the clsnam is not Security_Class, SS$_INVCLSITM is returned.
OSS$_OBJECT_NAME	Returns the name of the object. The FILE class does not return an object name.
OSS$_OWNER	Returns the UIC or general identifier of the object’s owner.
OSS$_PROTECTION	Returns the protection code of the object.

contxt

OpenVMS usage:	context
Type:	longword (unsigned)
Access:	modify
Mechanism:	by reference

Value used to maintain the processing context when dealing with a single protected object across multiple $GET_SECURITY/$SET_SECURITY calls.

Whenever the context value is nonzero, the class name, object name, or object handle arguments are disregarded. An input value of 0 indicates that a new context should be established.

Because an active context block consumes process memory, be sure to release the context block by setting the RELCTX flag when the profile processing is complete. $GET_SECURITY sets the context argument to 0 once the context is released.

acmode

OpenVMS usage:	access_mode
Type:	longword (unsigned)
Access:	read_only
Mechanism:	by reference

Access mode to be used in the object protection check. The acmode argument is the address of a longword containing the access mode. The acmode argument defaults to kernel mode; however, the system compares acmode with the caller’s access mode and uses the least privileged mode. The access modes are defined in the system macro $PSLDEF library. VSI recommends that this argument be omitted (passed as zero).

Required Access or Privileges

Read or control access to the object is required.

Required Quota

None

Condition Values Returned

Value	Description	SS$_NORMAL	The service completed successfully
SS$_ACCVIO	The parameter cannot be read and the buffer cannot be written.
SS$_BADPARAM	You specified an invalid object, attribute code, or item size.
SS$_INSFARG	The clsnam and objnam arguments are not specified, the clsnam and objhan arguments are not specified, or the contxt argument is not specified.
SS$_INVCLSITM	The item code that you specified is not supported for the class.
SS$_NOCLASS	The named security class does not exist.
SS$_OBJLOCKED	The selected object is currently write locked.

See also

• $SET_SECURITY
• Example by James Duff