MdeModulePkg/Include/Protocol/VariablePolicy.h

/** @file -- VariablePolicy.h

This protocol allows communication with Variable Policy Engine.

Copyright (c) Microsoft Corporation.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/

#ifndef __EDKII_VARIABLE_POLICY_PROTOCOL__
#define __EDKII_VARIABLE_POLICY_PROTOCOL__

#define EDKII_VARIABLE_POLICY_PROTOCOL_REVISION  0x0000000000020000

/*
  Rev 0x0000000000010000:
    - Initial protocol definition

  Rev 0x0000000000020000:
    - Add GetVariablePolicyInfo() API
    - Add GetLockOnVariableStateVariablePolicyInfo() API

*/

#define EDKII_VARIABLE_POLICY_PROTOCOL_GUID \
  { \
    0x81D1675C, 0x86F6, 0x48DF, { 0xBD, 0x95, 0x9A, 0x6E, 0x4F, 0x09, 0x25, 0xC3 } \
  }

#define VARIABLE_POLICY_ENTRY_REVISION  0x00010000

#pragma pack(push, 1)
typedef struct {
  UINT32      Version;
  UINT16      Size;
  UINT16      OffsetToName;
  EFI_GUID    Namespace;
  UINT32      MinSize;
  UINT32      MaxSize;
  UINT32      AttributesMustHave;
  UINT32      AttributesCantHave;
  UINT8       LockPolicyType;
  UINT8       Padding[3];
  // UINT8    LockPolicy[];     // Variable Length Field
  // CHAR16   Name[]            // Variable Length Field
} VARIABLE_POLICY_ENTRY;

#define     VARIABLE_POLICY_NO_MIN_SIZE   0
#define     VARIABLE_POLICY_NO_MAX_SIZE   MAX_UINT32
#define     VARIABLE_POLICY_NO_MUST_ATTR  0
#define     VARIABLE_POLICY_NO_CANT_ATTR  0

#define     VARIABLE_POLICY_TYPE_NO_LOCK            0
#define     VARIABLE_POLICY_TYPE_LOCK_NOW           1
#define     VARIABLE_POLICY_TYPE_LOCK_ON_CREATE     2
#define     VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE  3

typedef struct {
  EFI_GUID    Namespace;
  UINT8       Value;
  UINT8       Padding;
  // CHAR16   Name[];           // Variable Length Field
} VARIABLE_LOCK_ON_VAR_STATE_POLICY;
#pragma pack(pop)

/**
  This API function disables the variable policy enforcement. If it's
  already been called once, will return EFI_ALREADY_STARTED.

  @retval     EFI_SUCCESS
  @retval     EFI_ALREADY_STARTED   Has already been called once this boot.
  @retval     EFI_WRITE_PROTECTED   Interface has been locked until reboot.
  @retval     EFI_WRITE_PROTECTED   Interface option is disabled by platform PCD.

**/
typedef
EFI_STATUS
(EFIAPI *DISABLE_VARIABLE_POLICY)(
  VOID
  );

/**
  This API function returns whether or not the policy engine is
  currently being enforced.

  @param[out]   State       Pointer to a return value for whether the policy enforcement
                            is currently enabled.

  @retval     EFI_SUCCESS
  @retval     Others        An error has prevented this command from completing.

**/
typedef
EFI_STATUS
(EFIAPI *IS_VARIABLE_POLICY_ENABLED)(
  OUT BOOLEAN *State
  );

/**
  This API function validates and registers a new policy with
  the policy enforcement engine.

  @param[in]  NewPolicy     Pointer to the incoming policy structure.

  @retval     EFI_SUCCESS
  @retval     EFI_INVALID_PARAMETER   NewPolicy is NULL or is internally inconsistent.
  @retval     EFI_ALREADY_STARTED     An identical matching policy already exists.
  @retval     EFI_WRITE_PROTECTED     The interface has been locked until the next reboot.
  @retval     EFI_ABORTED             A calculation error has prevented this function from completing.
  @retval     EFI_OUT_OF_RESOURCES    Cannot grow the table to hold any more policies.

**/
typedef
EFI_STATUS
(EFIAPI *REGISTER_VARIABLE_POLICY)(
  IN CONST VARIABLE_POLICY_ENTRY  *PolicyEntry
  );

/**
  This API function will dump the entire contents of the variable policy table.

  Similar to GetVariable, the first call can be made with a 0 size and it will return
  the size of the buffer required to hold the entire table.

  @param[out]     Policy  Pointer to the policy buffer. Can be NULL if Size is 0.
  @param[in,out]  Size    On input, the size of the output buffer. On output, the size
                          of the data returned.

  @retval     EFI_SUCCESS             Policy data is in the output buffer and Size has been updated.
  @retval     EFI_INVALID_PARAMETER   Size is NULL, or Size is non-zero and Policy is NULL.
  @retval     EFI_BUFFER_TOO_SMALL    Size is insufficient to hold policy. Size updated with required size.

**/
typedef
EFI_STATUS
(EFIAPI *DUMP_VARIABLE_POLICY)(
  IN OUT UINT8  *Policy,
  IN OUT UINT32 *Size
  );

/**
  This API function locks the interface so that no more policy updates
  can be performed or changes made to the enforcement until the next boot.

  @retval     EFI_SUCCESS
  @retval     Others        An error has prevented this command from completing.

**/
typedef
EFI_STATUS
(EFIAPI *LOCK_VARIABLE_POLICY)(
  VOID
  );

/**
  This function will return variable policy information for a UEFI variable with a
  registered variable policy.

  @param[in]      VariableName                          The name of the variable to use for the policy search.
  @param[in]      VendorGuid                            The vendor GUID of the variable to use for the policy search.
  @param[in,out]  VariablePolicyVariableNameBufferSize  On input, the size, in bytes, of the VariablePolicyVariableName
                                                        buffer.

                                                        On output, the size, in bytes, needed to store the variable
                                                        policy variable name.

                                                        If testing for the VariablePolicyVariableName buffer size
                                                        needed, set this value to zero so EFI_BUFFER_TOO_SMALL is
                                                        guaranteed to be returned if the variable policy variable name
                                                        is found.
  @param[out]     VariablePolicy                        Pointer to a buffer where the policy entry will be written
                                                        if found.
  @param[out]     VariablePolicyVariableName            Pointer to a buffer where the variable name used for the
                                                        variable policy will be written if a variable name is
                                                        registered.

                                                        If the variable policy is not associated with a variable name
                                                        (e.g. applied to variable vendor namespace) and this parameter
                                                        is given, this parameter will not be modified and
                                                        VariablePolicyVariableNameBufferSize will be set to zero to
                                                        indicate a name was not present.

                                                        If the pointer given is not NULL,
                                                        VariablePolicyVariableNameBufferSize must be non-NULL.

  @retval     EFI_SUCCESS             A variable policy entry was found and returned successfully.
  @retval     EFI_BAD_BUFFER_SIZE     An internal buffer size caused a calculation error.
  @retval     EFI_BUFFER_TOO_SMALL    The VariablePolicyVariableName buffer value is too small for the size needed.
                                      The buffer should now point to the size needed.
  @retval     EFI_NOT_READY           Variable policy has not yet been initialized.
  @retval     EFI_INVALID_PARAMETER   A required pointer argument passed is NULL. This will be returned if
                                      VariablePolicyVariableName is non-NULL and VariablePolicyVariableNameBufferSize
                                      is NULL.
  @retval     EFI_NOT_FOUND           A variable policy was not found for the given UEFI variable name and vendor GUID.

**/
typedef
EFI_STATUS
(EFIAPI *GET_VARIABLE_POLICY_INFO)(
  IN      CONST CHAR16                *VariableName,
  IN      CONST EFI_GUID              *VendorGuid,
  IN OUT  UINTN                       *VariablePolicyVariableNameBufferSize OPTIONAL,
  OUT     VARIABLE_POLICY_ENTRY       *VariablePolicy,
  OUT     CHAR16                      *VariablePolicyVariableName OPTIONAL
  );

/**
  This function will return the Lock on Variable State policy information for the policy
  associated with the given UEFI variable.

  @param[in]      VariableName                              The name of the variable to use for the policy search.
  @param[in]      VendorGuid                                The vendor GUID of the variable to use for the policy
                                                            search.
  @param[in,out]  VariableLockPolicyVariableNameBufferSize  On input, the size, in bytes, of the
                                                            VariableLockPolicyVariableName buffer.

                                                            On output, the size, in bytes, needed to store the variable
                                                            policy variable name.

                                                            If testing for the VariableLockPolicyVariableName buffer
                                                            size needed, set this value to zero so EFI_BUFFER_TOO_SMALL
                                                            is guaranteed to be returned if the variable policy variable
                                                            name is found.
  @param[out]     VariablePolicy                            Pointer to a buffer where the policy entry will be written
                                                            if found.
  @param[out]     VariableLockPolicyVariableName            Pointer to a buffer where the variable name used for the
                                                            variable lock on variable state policy will be written if
                                                            a variable name is registered.

                                                            If the lock on variable policy is not associated with a
                                                            variable name (e.g. applied to variable vendor namespace)
                                                            and this parameter is given, this parameter will not be
                                                            modified and VariableLockPolicyVariableNameBufferSize will
                                                            be set to zero to indicate a name was not present.

                                                            If the pointer given is not NULL,
                                                            VariableLockPolicyVariableNameBufferSize must be non-NULL.

  @retval     EFI_SUCCESS             A Lock on Variable State variable policy entry was found and returned
                                      successfully.
  @retval     EFI_BAD_BUFFER_SIZE     An internal buffer size caused a calculation error.
  @retval     EFI_BUFFER_TOO_SMALL    The VariableLockPolicyVariableName buffer is too small for the size needed.
                                      The buffer should now point to the size needed.
  @retval     EFI_NOT_READY           Variable policy has not yet been initialized.
  @retval     EFI_INVALID_PARAMETER   A required pointer argument passed is NULL. This will be returned if
                                      VariableLockPolicyVariableName is non-NULL and
                                      VariableLockPolicyVariableNameBufferSize is NULL.
  @retval     EFI_NOT_FOUND           A Lock on Variable State variable policy was not found for the given UEFI
                                      variable name and vendor GUID.

**/
typedef
EFI_STATUS
(EFIAPI *GET_LOCK_ON_VARIABLE_STATE_VARIABLE_POLICY_INFO)(
  IN      CONST CHAR16                        *VariableName,
  IN      CONST EFI_GUID                      *VendorGuid,
  IN OUT  UINTN                               *VariableLockPolicyVariableNameBufferSize OPTIONAL,
  OUT     VARIABLE_LOCK_ON_VAR_STATE_POLICY   *VariablePolicy,
  OUT     CHAR16                              *VariableLockPolicyVariableName OPTIONAL
  );

typedef struct {
  UINT64                                             Revision;
  DISABLE_VARIABLE_POLICY                            DisableVariablePolicy;
  IS_VARIABLE_POLICY_ENABLED                         IsVariablePolicyEnabled;
  REGISTER_VARIABLE_POLICY                           RegisterVariablePolicy;
  DUMP_VARIABLE_POLICY                               DumpVariablePolicy;
  LOCK_VARIABLE_POLICY                               LockVariablePolicy;
  GET_VARIABLE_POLICY_INFO                           GetVariablePolicyInfo;
  GET_LOCK_ON_VARIABLE_STATE_VARIABLE_POLICY_INFO    GetLockOnVariableStateVariablePolicyInfo;
} _EDKII_VARIABLE_POLICY_PROTOCOL;

typedef _EDKII_VARIABLE_POLICY_PROTOCOL EDKII_VARIABLE_POLICY_PROTOCOL;

extern EFI_GUID  gEdkiiVariablePolicyProtocolGuid;

#endif