Virtual memory endpoint

This endpoint is intended for managing virtual memory.

Information about methods of the endpoint is provided in the table below.

Methods of the vmm.VMM endpoint (kl.core.VMM interface)

Method

Method purpose and parameters

Potential danger of the method

Allocate

Purpose

Allocates (reserves and optionally commits) a virtual memory region.

Parameters

  • [in] addr – preferred base address of the virtual memory region, or 0 for the base address to be selected automatically.
  • [in] size – size of the virtual memory region in bytes.
  • [in] flags – flags defining the parameters of the virtual memory region.
  • [out] va – base address of the allocated virtual memory region.
  • [out] rc – return code.

Allows the following:

  • Exhaust the kernel memory by creating a multitude of objects within it.
  • Exhaust the RAM.

Commit

Purpose

Commits a virtual memory region that was reserved by the Allocate method.

Parameters

  • [in] va – base address of the virtual memory region.
  • [in] size – size of the virtual memory region in bytes.
  • [in] flags – fictitious parameter.
  • [out] rc – return code.

Exhausts RAM.

Decommit

Purpose

Decommits a virtual memory region.

Parameters

  • [in] va – base address of the virtual memory region.
  • [in] size – size of the virtual memory region in bytes.
  • [out] rc – return code.

N/A

Protect

Purpose

Modifies the access rights to the virtual memory region.

Parameters

  • [in] va – base address of the virtual memory region.
  • [in] size – size of the virtual memory region in bytes.
  • [in] flags – flags defining the access rights to the virtual memory region.
  • [out] rc – return code.

N/A

Free

Purpose

Frees up the virtual memory region.

Parameters

  • [in] va – base address of the virtual memory region.
  • [in] size – size of the virtual memory region in bytes.
  • [out] rc – return code.

N/A

Query

Purpose

Gets information about a virtual memory page.

Parameters

  • [in] va – address included in the virtual memory page.
  • [out] info – sequence containing information about a virtual memory page.
  • [out] rc – return code.

N/A

MdlCreate

Purpose

Creates an MDL buffer.

Parameters

  • [in] size – size of the MDL buffer in bytes.
  • [in] prot – flags defining the access rights to the MDL buffer.
  • [out] handle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the MDL buffer.
  • [out] rc – return code.

Allows the following:

  • Exhaust the kernel memory by creating a multitude of objects within it.
  • Exhaust the RAM.

MdlCreateFromVm

Purpose

Creates an MDL buffer from physical memory that is mapped to the defined virtual memory region and maps the created MDL buffer to this region.

Parameters

  • [in] va – base address of the virtual memory region.
  • [in] size – size of the virtual memory region in bytes.
  • [in] flags – flags defining the access rights to the MDL buffer.
  • [out] handle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the MDL buffer.
  • [out] rc – return code.

Allows the following:

  • Exhaust the kernel memory by creating a multitude of objects within it.
  • Exhaust the RAM.

MdlGetSize

Purpose

Gets the size of the MDL buffer.

Parameters

  • [in] handle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the MDL buffer.
  • [out] size – size of the MDL buffer in bytes.
  • [out] rc – return code.

N/A

MdlMap

Purpose

Reserves a virtual memory region and maps the MDL buffer to it.

Parameters

  • [in] handle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the MDL buffer.
  • [in] offset – offset (in bytes) in the MDL buffer where mapping should start.
  • [in] length – size (in bytes) of the part of the MDL buffer that needs to be mapped.
  • [in] hint – preferred base address of the virtual memory region, or 0 for the base address to be selected automatically.
  • [in] prot – flags defining the parameters of the virtual memory region.
  • [out] address – base address of the virtual memory region.
  • [out] rc – return code.

Allows the following:

  • Create shared memory for interprocess communication concealed from the security module if multiple processes own the handles of one MDL buffer (the handle permissions masks must allow mapping of the MDL buffer).
  • Exhaust the kernel memory by creating a multitude of objects within it.

MdlClone

Purpose

Creates an MDL buffer based on an existing one.

The MDL buffer is created from the same regions of physical memory as the original buffer.

Parameters

  • [in] originHandle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the original MDL buffer.
  • [in] offset – offset (in bytes) in the original MDL buffer where duplication should start.
  • [in] length – size (in bytes) of the part of the original MDL buffer that needs to be duplicated.
  • [out] cloneHandle – value whose binary representation consists of multiple fields, including a handle field and a handle permissions mask field. The handle identifies the created MDL buffer.
  • [out] rc – return code.

Allows the kernel memory to be used up by creating a multitude of objects within it.

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