#ifndef _NTRTL_H

/**
 * The RtlSetOwnerSecurityDescriptor routine sets the owner information of an absolute-format security descriptor. It replaces any owner information that is already present in the security descriptor.
 *
 * \param SecurityDescriptor Pointer to the SECURITY_DESCRIPTOR structure whose owner is to be set. RtlSetOwnerSecurityDescriptor replaces any existing owner with the new owner.
 * \param Owner Pointer to a security identifier (SID) structure for the security descriptor's new primary owner.
 * \li \c This pointer, not the SID structure itself, is copied into the security descriptor.
 * \li \c If this parameter is NULL, RtlSetOwnerSecurityDescriptor clears the security descriptor's owner information. This marks the security descriptor as having no owner.
 * \param OwnerDefaulted Set to TRUE if the owner information is derived from a default mechanism.
 * \li \c If this value is TRUE, it is default information. RtlSetOwnerSecurityDescriptor sets the SE_OWNER_DEFAULTED flag in the security descriptor's SECURITY_DESCRIPTOR_CONTROL field.
 * \li \c If this parameter is FALSE, the SE_OWNER_DEFAULTED flag is cleared.
 * \return NTSTATUS Successful or errant status.
 * \see https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntifs/nf-ntifs-rtlsetownersecuritydescriptor
 */
NTSYSAPI
NTSTATUS
NTAPI
RtlSetOwnerSecurityDescriptor(
    _Inout_ PSECURITY_DESCRIPTOR SecurityDescriptor,
    _In_opt_ PSID Owner,
    _In_ BOOLEAN OwnerDefaulted
    );

#endif
View code on GitHub

// ntifs.h

NTSYSAPI NTSTATUS RtlSetOwnerSecurityDescriptor(
  [in, out]      PSECURITY_DESCRIPTOR SecurityDescriptor,
  [in, optional] PSID                 Owner,
  [in, optional] BOOLEAN              OwnerDefaulted
);
View the official Windows Driver Kit DDI reference