RtlSelfRelativeToAbsoluteSD function (ntifs.h)

Article
11/04/2022

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

Syntax

NTSYSAPI NTSTATUS RtlSelfRelativeToAbsoluteSD(
  [in]      PSECURITY_DESCRIPTOR SelfRelativeSecurityDescriptor,
  [out]     PSECURITY_DESCRIPTOR AbsoluteSecurityDescriptor,
  [in, out] PULONG               AbsoluteSecurityDescriptorSize,
  [out]     PACL                 Dacl,
  [in, out] PULONG               DaclSize,
  [out]     PACL                 Sacl,
  [in, out] PULONG               SaclSize,
  [out]     PSID                 Owner,
  [in, out] PULONG               OwnerSize,
  [out]     PSID                 PrimaryGroup,
  [in, out] PULONG               PrimaryGroupSize
);

Parameters

[in] SelfRelativeSecurityDescriptor

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

[out] AbsoluteSecurityDescriptor

Pointer to a caller-allocated buffer that receives the main body of an absolute-format security descriptor. This information is formatted as a SECURITY_DESCRIPTOR structure.

[in, out] AbsoluteSecurityDescriptorSize

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

[out] Dacl

Pointer to a caller-allocated buffer that receives the DACL of the absolute-format security descriptor. The main body of the absolute-format security descriptor references this pointer.

[in, out] DaclSize

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

[out] Sacl

Pointer to a caller-allocated buffer that receives the SACL of the absolute-format security descriptor. The main body of the absolute-format security descriptor references this pointer.

[in, out] SaclSize

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

[out] Owner

Pointer to a caller-allocated buffer that receives the SID of the owner of the absolute-format security descriptor. The main body of the absolute-format security descriptor references this pointer.

[in, out] OwnerSize

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

[out] PrimaryGroup

Pointer to a caller-allocated buffer that receives the SID of the primary group of the absolute-format security descriptor. The main body of the absolute-format security descriptor references this pointer.

[in, out] PrimaryGroupSize

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

Return value

RtlSelfRelativeToAbsoluteSD 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 AbsoluteSecurityDescriptor , Dacl, Sacl, Owner, or PrimaryGroup parameter was too small. STATUS_BUFFER_TOO_SMALL is an error code.

Remarks

A security descriptor in absolute format contains pointers to the information, 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 floppy disk or transmitted by means of a communications protocol.

Note that the AbsoluteSecurityDescriptor parameter receives only the main body of the absolute security descriptor. The entire absolute security descriptor consists of this main body, plus all of the security descriptor components returned in the Dacl, Sacl, Owner, and PrimaryGroup buffers. Thus, the caller cannot free these buffers after calling RtlSelfRelativeToAbsoluteSD, because doing so would invalidate the absolute security descriptor.

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

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
IRQL	<= APC_LEVEL