RtlAbsoluteToSelfRelativeSD function (ntifs.h)

Article
11/04/2022

The RtlAbsoluteToSelfRelativeSD routine creates a new security descriptor in self-relative format by using a security descriptor in absolute format as a template.

Syntax

NTSYSAPI NTSTATUS RtlAbsoluteToSelfRelativeSD(
  [in]      PSECURITY_DESCRIPTOR AbsoluteSecurityDescriptor,
  [out]     PSECURITY_DESCRIPTOR SelfRelativeSecurityDescriptor,
  [in, out] PULONG               BufferLength
);

Parameters

[in] AbsoluteSecurityDescriptor

Pointer to a caller-allocated buffer that contains a SECURITY_DESCRIPTOR structure in absolute format. RtlAbsoluteToSelfRelativeSD creates a version of this security descriptor in self-relative format without modifying the original.

[out] SelfRelativeSecurityDescriptor

Pointer to a caller-allocated buffer that receives a security descriptor in self-relative format.

[in, out] BufferLength

Pointer to a caller-allocated variable that specifies the size, in bytes, of the buffer pointed to by the SelfRelativeSecurityDescriptor parameter. If the buffer is not large enough to hold the security descriptor, RtlAbsoluteToSelfRelativeSD returns STATUS_BUFFER_TOO_SMALL and sets this variable to the minimum required size.

Return value

RtlAbsoluteToSelfRelativeSD returns STATUS_SUCCESS or an appropriate NTSTATUS value such as one of the following:

Return code	Description
STATUS_BAD_DESCRIPTOR_FORMAT	The buffer pointed to by the AbsoluteSecurityDescriptor parameter did not contain a SECURITY_DESCRIPTOR structure in absolute format. STATUS_BAD_DESCRIPTOR_FORMAT is an error code.
STATUS_BUFFER_TOO_SMALL	The buffer pointed to by the SelfRelativeSecurityDescriptor parameter was too small to contain the security descriptor in self-relative format. STATUS_BUFFER_TOO_SMALL is an error code.

Remarks

A security descriptor in absolute format contains pointers to the information it contains, rather than containing the information itself. A security descriptor in self-relative format contains the information in a contiguous block of memory. In a self-relative security descriptor, a SECURITY_DESCRIPTOR structure always starts the information, but the security descriptor's other components can follow the SECURITY_DESCRIPTOR structure in any order. Instead of using memory addresses, the components of the security descriptor are identified by offsets from the beginning of the security descriptor. This format is useful when a security descriptor must be stored on a disk or transmitted by means of a communications protocol.

To create a new security descriptor in absolute format by using a security descriptor in self-relative format as a template, use RtlSelfRelativeToAbsoluteSD.

For more information about security and access control, see the Microsoft Windows SDK documentation.

Requirements

Requirement	Value
Minimum supported client	Windows Server 2003 SP1
Target Platform	Universal
Header	ntifs.h (include Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe (kernel mode); Ntdll.dll (user mode)
IRQL	<= APC_LEVEL