diff options
Diffstat (limited to 'MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c')
| -rw-r--r-- | MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c | 830 |
1 files changed, 830 insertions, 0 deletions
diff --git a/MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c b/MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c new file mode 100644 index 0000000000..5029ddb96a --- /dev/null +++ b/MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c @@ -0,0 +1,830 @@ +/** @file -- VariablePolicyLib.c
+Business logic for Variable Policy enforcement.
+
+Copyright (c) Microsoft Corporation.
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi.h>
+
+#include <Library/SafeIntLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
+
+#include <Protocol/VariablePolicy.h>
+#include <Library/VariablePolicyLib.h>
+
+
+// IMPORTANT NOTE: This library is currently rife with multiple return statements
+// for error handling. A refactor should remove these at some point.
+
+//
+// This library was designed with advanced unit-test features.
+// This define handles the configuration.
+#ifdef INTERNAL_UNIT_TEST
+#undef STATIC
+#define STATIC // Nothing...
+#endif
+
+// An abstracted GetVariable interface that enables configuration regardless of the environment.
+EFI_GET_VARIABLE mGetVariableHelper = NULL;
+
+// Master switch to lock this entire interface. Does not stop enforcement,
+// just prevents the configuration from being changed for the rest of the boot.
+STATIC BOOLEAN mInterfaceLocked = FALSE;
+
+// Master switch to disable the entire interface for a single boot.
+// This will disable all policy enforcement for the duration of the boot.
+STATIC BOOLEAN mProtectionDisabled = FALSE;
+
+// Table to hold all the current policies.
+UINT8 *mPolicyTable = NULL;
+STATIC UINT32 mCurrentTableSize = 0;
+STATIC UINT32 mCurrentTableUsage = 0;
+STATIC UINT32 mCurrentTableCount = 0;
+
+#define POLICY_TABLE_STEP_SIZE 0x1000
+
+// NOTE: DO NOT USE THESE MACROS on any structure that has not been validated.
+// Current table data has already been sanitized.
+#define GET_NEXT_POLICY(CurPolicy) (VARIABLE_POLICY_ENTRY*)((UINT8*)CurPolicy + CurPolicy->Size)
+#define GET_POLICY_NAME(CurPolicy) (CHAR16*)((UINTN)CurPolicy + CurPolicy->OffsetToName)
+
+#define MATCH_PRIORITY_EXACT 0
+#define MATCH_PRIORITY_MAX MATCH_PRIORITY_EXACT
+#define MATCH_PRIORITY_MIN MAX_UINT8
+
+
+/**
+ An extra init hook that enables the RuntimeDxe library instance to
+ register VirtualAddress change callbacks. Among other things.
+
+ @retval EFI_SUCCESS Everything is good. Continue with init.
+ @retval Others Uh... don't continue.
+
+**/
+EFI_STATUS
+VariablePolicyExtraInit (
+ VOID
+ );
+
+/**
+ An extra deinit hook that enables the RuntimeDxe library instance to
+ register VirtualAddress change callbacks. Among other things.
+
+ @retval EFI_SUCCESS Everything is good. Continue with deinit.
+ @retval Others Uh... don't continue.
+
+**/
+EFI_STATUS
+VariablePolicyExtraDeinit (
+ VOID
+ );
+
+
+/**
+ This helper function determines whether the structure of an incoming policy
+ is valid and internally consistent.
+
+ @param[in] NewPolicy Pointer to the incoming policy structure.
+
+ @retval TRUE
+ @retval FALSE Pointer is NULL, size is wrong, strings are empty, or
+ substructures overlap.
+
+**/
+STATIC
+BOOLEAN
+IsValidVariablePolicyStructure (
+ IN CONST VARIABLE_POLICY_ENTRY *NewPolicy
+ )
+{
+ EFI_STATUS Status;
+ UINTN EntryEnd;
+ CHAR16 *CheckChar;
+ UINTN WildcardCount;
+
+ // Sanitize some quick values.
+ if (NewPolicy == NULL || NewPolicy->Size == 0 ||
+ // Structure size should be at least as long as the minumum structure and a NULL string.
+ NewPolicy->Size < sizeof(VARIABLE_POLICY_ENTRY) ||
+ // Check for the known revision.
+ NewPolicy->Version != VARIABLE_POLICY_ENTRY_REVISION) {
+ return FALSE;
+ }
+
+ // Calculate the theoretical end of the structure and make sure
+ // that the structure can fit in memory.
+ Status = SafeUintnAdd( (UINTN)NewPolicy, NewPolicy->Size, &EntryEnd );
+ if (EFI_ERROR( Status )) {
+ return FALSE;
+ }
+
+ // Check for a valid Max Size.
+ if (NewPolicy->MaxSize == 0) {
+ return FALSE;
+ }
+
+ // Check for the valid list of lock policies.
+ if (NewPolicy->LockPolicyType != VARIABLE_POLICY_TYPE_NO_LOCK &&
+ NewPolicy->LockPolicyType != VARIABLE_POLICY_TYPE_LOCK_NOW &&
+ NewPolicy->LockPolicyType != VARIABLE_POLICY_TYPE_LOCK_ON_CREATE &&
+ NewPolicy->LockPolicyType != VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE)
+ {
+ return FALSE;
+ }
+
+ // If the policy type is VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE, make sure that the matching state variable Name
+ // terminates before the OffsetToName for the matching policy variable Name.
+ if (NewPolicy->LockPolicyType == VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE) {
+ // Adjust CheckChar to the offset of the LockPolicy->Name.
+ Status = SafeUintnAdd( (UINTN)NewPolicy + sizeof(VARIABLE_POLICY_ENTRY),
+ sizeof(VARIABLE_LOCK_ON_VAR_STATE_POLICY),
+ (UINTN*)&CheckChar );
+ if (EFI_ERROR( Status ) || EntryEnd <= (UINTN)CheckChar) {
+ return FALSE;
+ }
+ while (*CheckChar != CHAR_NULL) {
+ if (EntryEnd <= (UINTN)CheckChar) {
+ return FALSE;
+ }
+ CheckChar++;
+ }
+ // At this point we should have either exeeded the structure or be pointing at the last char in LockPolicy->Name.
+ // We should check to make sure that the policy Name comes immediately after this charcter.
+ if ((UINTN)++CheckChar != (UINTN)NewPolicy + NewPolicy->OffsetToName) {
+ return FALSE;
+ }
+ // If the policy type is any other value, make sure that the LockPolicy structure has a zero length.
+ } else {
+ if (NewPolicy->OffsetToName != sizeof(VARIABLE_POLICY_ENTRY)) {
+ return FALSE;
+ }
+ }
+
+ // Check to make sure that the name has a terminating character
+ // before the end of the structure.
+ // We've already checked that the name is within the bounds of the structure.
+ if (NewPolicy->Size != NewPolicy->OffsetToName) {
+ CheckChar = (CHAR16*)((UINTN)NewPolicy + NewPolicy->OffsetToName);
+ WildcardCount = 0;
+ while (*CheckChar != CHAR_NULL) {
+ // Make sure there aren't excessive wildcards.
+ if (*CheckChar == '#') {
+ WildcardCount++;
+ if (WildcardCount > MATCH_PRIORITY_MIN) {
+ return FALSE;
+ }
+ }
+ // Make sure you're still within the bounds of the policy structure.
+ if (EntryEnd <= (UINTN)CheckChar) {
+ return FALSE;
+ }
+ CheckChar++;
+ }
+
+ // Finally, we should be pointed at the very last character in Name, so we should be right
+ // up against the end of the structure.
+ if ((UINTN)++CheckChar != EntryEnd) {
+ return FALSE;
+ }
+ }
+
+ return TRUE;
+}
+
+
+/**
+ This helper function evaluates a policy and determines whether it matches the target
+ variable. If matched, will also return a value corresponding to the priority of the match.
+
+ The rules for "best match" are listed in the Variable Policy Spec.
+ Perfect name matches will return 0.
+ Single wildcard characters will return the number of wildcard characters.
+ Full namespaces will return MAX_UINT8.
+
+ @param[in] EvalEntry Pointer to the policy entry being evaluated.
+ @param[in] VariableName Same as EFI_SET_VARIABLE.
+ @param[in] VendorGuid Same as EFI_SET_VARIABLE.
+ @param[out] MatchPriority [Optional] On finding a match, this value contains the priority of the match.
+ Lower number == higher priority. Only valid if a match found.
+
+ @retval TRUE Current entry matches the target variable.
+ @retval FALSE Current entry does not match at all.
+
+**/
+STATIC
+BOOLEAN
+EvaluatePolicyMatch (
+ IN CONST VARIABLE_POLICY_ENTRY *EvalEntry,
+ IN CONST CHAR16 *VariableName,
+ IN CONST EFI_GUID *VendorGuid,
+ OUT UINT8 *MatchPriority OPTIONAL
+ )
+{
+ BOOLEAN Result;
+ CHAR16 *PolicyName;
+ UINT8 CalculatedPriority;
+ UINTN Index;
+
+ Result = FALSE;
+ CalculatedPriority = MATCH_PRIORITY_EXACT;
+
+ // Step 1: If the GUID doesn't match, we're done. No need to evaluate anything else.
+ if (!CompareGuid( &EvalEntry->Namespace, VendorGuid )) {
+ goto Exit;
+ }
+
+ // If the GUID matches, check to see whether there is a Name associated
+ // with the policy. If not, this policy matches the entire namespace.
+ // Missing Name is indicated by size being equal to name.
+ if (EvalEntry->Size == EvalEntry->OffsetToName) {
+ CalculatedPriority = MATCH_PRIORITY_MIN;
+ Result = TRUE;
+ goto Exit;
+ }
+
+ // Now that we know the name exists, get it.
+ PolicyName = GET_POLICY_NAME( EvalEntry );
+
+ // Evaluate the name against the policy name and check for a match.
+ // Account for any wildcards.
+ Index = 0;
+ Result = TRUE;
+ // Keep going until the end of both strings.
+ while (PolicyName[Index] != CHAR_NULL || VariableName[Index] != CHAR_NULL) {
+ // If we don't have a match...
+ if (PolicyName[Index] != VariableName[Index] || PolicyName[Index] == '#') {
+ // If this is a numerical wildcard, we can consider
+ // it a match if we alter the priority.
+ if (PolicyName[Index] == L'#' &&
+ ((L'0' <= VariableName[Index] && VariableName[Index] <= L'9') ||
+ (L'A' <= VariableName[Index] && VariableName[Index] <= L'F') ||
+ (L'a' <= VariableName[Index] && VariableName[Index] <= L'f'))) {
+ if (CalculatedPriority < MATCH_PRIORITY_MIN) {
+ CalculatedPriority++;
+ }
+ // Otherwise, not a match.
+ } else {
+ Result = FALSE;
+ goto Exit;
+ }
+ }
+ Index++;
+ }
+
+Exit:
+ if (Result && MatchPriority != NULL) {
+ *MatchPriority = CalculatedPriority;
+ }
+ return Result;
+}
+
+
+/**
+ This helper function walks the current policy table and returns a pointer
+ to the best match, if any are found. Leverages EvaluatePolicyMatch() to
+ determine "best".
+
+ @param[in] VariableName Same as EFI_SET_VARIABLE.
+ @param[in] VendorGuid Same as EFI_SET_VARIABLE.
+ @param[out] ReturnPriority [Optional] If pointer is provided, return the
+ priority of the match. Same as EvaluatePolicyMatch().
+ Only valid if a match is returned.
+
+ @retval VARIABLE_POLICY_ENTRY* Best match that was found.
+ @retval NULL No match was found.
+
+**/
+STATIC
+VARIABLE_POLICY_ENTRY*
+GetBestPolicyMatch (
+ IN CONST CHAR16 *VariableName,
+ IN CONST EFI_GUID *VendorGuid,
+ OUT UINT8 *ReturnPriority OPTIONAL
+ )
+{
+ VARIABLE_POLICY_ENTRY *BestResult;
+ VARIABLE_POLICY_ENTRY *CurrentEntry;
+ UINT8 MatchPriority;
+ UINT8 CurrentPriority;
+ UINTN Index;
+
+ BestResult = NULL;
+ MatchPriority = MATCH_PRIORITY_EXACT;
+
+ // Walk all entries in the table, looking for matches.
+ CurrentEntry = (VARIABLE_POLICY_ENTRY*)mPolicyTable;
+ for (Index = 0; Index < mCurrentTableCount; Index++) {
+ // Check for a match.
+ if (EvaluatePolicyMatch( CurrentEntry, VariableName, VendorGuid, &CurrentPriority )) {
+ // If match is better, take it.
+ if (BestResult == NULL || CurrentPriority < MatchPriority) {
+ BestResult = CurrentEntry;
+ MatchPriority = CurrentPriority;
+ }
+
+ // If you've hit the highest-priority match, can exit now.
+ if (MatchPriority == 0) {
+ break;
+ }
+ }
+
+ // If we're still in the loop, move to the next entry.
+ CurrentEntry = GET_NEXT_POLICY( CurrentEntry );
+ }
+
+ // If a return priority was requested, return it.
+ if (ReturnPriority != NULL) {
+ *ReturnPriority = MatchPriority;
+ }
+
+ return BestResult;
+}
+
+
+/**
+ 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_UNSUPPORTED Policy enforcement has been disabled. No reason to add more policies.
+ @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.
+ @retval EFI_NOT_READY Library has not yet been initialized.
+
+**/
+EFI_STATUS
+EFIAPI
+RegisterVariablePolicy (
+ IN CONST VARIABLE_POLICY_ENTRY *NewPolicy
+ )
+{
+ EFI_STATUS Status;
+ VARIABLE_POLICY_ENTRY *MatchPolicy;
+ UINT8 MatchPriority;
+ UINT32 NewSize;
+ UINT8 *NewTable;
+
+ if (!IsVariablePolicyLibInitialized()) {
+ return EFI_NOT_READY;
+ }
+ if (mInterfaceLocked) {
+ return EFI_WRITE_PROTECTED;
+ }
+
+ if (!IsValidVariablePolicyStructure( NewPolicy )) {
+ return EFI_INVALID_PARAMETER;
+ }
+
+ // Check to see whether an exact matching policy already exists.
+ MatchPolicy = GetBestPolicyMatch( GET_POLICY_NAME( NewPolicy ),
+ &NewPolicy->Namespace,
+ &MatchPriority );
+ if (MatchPolicy != NULL && MatchPriority == MATCH_PRIORITY_EXACT) {
+ return EFI_ALREADY_STARTED;
+ }
+
+ // If none exists, create it.
+ // If we need more space, allocate that now.
+ Status = SafeUint32Add( mCurrentTableUsage, NewPolicy->Size, &NewSize );
+ if (EFI_ERROR( Status )) {
+ return EFI_ABORTED;
+ }
+ if (NewSize > mCurrentTableSize) {
+ // Use NewSize to calculate the new table size in units of POLICY_TABLE_STEP_SIZE.
+ NewSize = (NewSize % POLICY_TABLE_STEP_SIZE) > 0 ?
+ (NewSize / POLICY_TABLE_STEP_SIZE) + 1 :
+ (NewSize / POLICY_TABLE_STEP_SIZE);
+ // Calculate the new table size in absolute bytes.
+ Status = SafeUint32Mult( NewSize, POLICY_TABLE_STEP_SIZE, &NewSize );
+ if (EFI_ERROR( Status )) {
+ return EFI_ABORTED;
+ }
+
+ // Reallocate and copy the table.
+ NewTable = AllocatePool( NewSize );
+ if (NewTable == NULL) {
+ return EFI_OUT_OF_RESOURCES;
+ }
+ CopyMem( NewTable, mPolicyTable, mCurrentTableUsage );
+ mCurrentTableSize = NewSize;
+ if (mPolicyTable != NULL) {
+ FreePool( mPolicyTable );
+ }
+ mPolicyTable = NewTable;
+ }
+ // Copy the policy into the table.
+ CopyMem( mPolicyTable + mCurrentTableUsage, NewPolicy, NewPolicy->Size );
+ mCurrentTableUsage += NewPolicy->Size;
+ mCurrentTableCount += 1;
+
+ // We're done here.
+
+ return EFI_SUCCESS;
+}
+
+
+/**
+ This API function checks to see whether the parameters to SetVariable would
+ be allowed according to the current variable policies.
+
+ @param[in] VariableName Same as EFI_SET_VARIABLE.
+ @param[in] VendorGuid Same as EFI_SET_VARIABLE.
+ @param[in] Attributes Same as EFI_SET_VARIABLE.
+ @param[in] DataSize Same as EFI_SET_VARIABLE.
+ @param[in] Data Same as EFI_SET_VARIABLE.
+
+ @retval EFI_SUCCESS A matching policy allows this update.
+ @retval EFI_SUCCESS There are currently no policies that restrict this update.
+ @retval EFI_SUCCESS The protections have been disable until the next reboot.
+ @retval EFI_WRITE_PROTECTED Variable is currently locked.
+ @retval EFI_INVALID_PARAMETER Attributes or size are invalid.
+ @retval EFI_ABORTED A lock policy exists, but an error prevented evaluation.
+ @retval EFI_NOT_READY Library has not been initialized.
+
+**/
+EFI_STATUS
+EFIAPI
+ValidateSetVariable (
+ IN CHAR16 *VariableName,
+ IN EFI_GUID *VendorGuid,
+ IN UINT32 Attributes,
+ IN UINTN DataSize,
+ IN VOID *Data
+ )
+{
+ BOOLEAN IsDel;
+ VARIABLE_POLICY_ENTRY *ActivePolicy;
+ EFI_STATUS Status;
+ EFI_STATUS ReturnStatus;
+ VARIABLE_LOCK_ON_VAR_STATE_POLICY *StateVarPolicy;
+ CHAR16 *StateVarName;
+ UINTN StateVarSize;
+ UINT8 StateVar;
+
+ ReturnStatus = EFI_SUCCESS;
+
+ if (!IsVariablePolicyLibInitialized()) {
+ ReturnStatus = EFI_NOT_READY;
+ goto Exit;
+ }
+
+ // Bail if the protections are currently disabled.
+ if (mProtectionDisabled) {
+ ReturnStatus = EFI_SUCCESS;
+ goto Exit;
+ }
+
+ // Determine whether this is a delete operation.
+ // If so, it will affect which tests are applied.
+ if ((DataSize == 0) && ((Attributes & EFI_VARIABLE_APPEND_WRITE) == 0)) {
+ IsDel = TRUE;
+ } else {
+ IsDel = FALSE;
+ }
+
+ // Find an active policy if one exists.
+ ActivePolicy = GetBestPolicyMatch( VariableName, VendorGuid, NULL );
+
+ // If we have an active policy, check it against the incoming data.
+ if (ActivePolicy != NULL) {
+ //
+ // Only enforce size and attribute constraints when updating data, not deleting.
+ if (!IsDel) {
+ // Check for size constraints.
+ if ((ActivePolicy->MinSize > 0 && DataSize < ActivePolicy->MinSize) ||
+ (ActivePolicy->MaxSize > 0 && DataSize > ActivePolicy->MaxSize)) {
+ ReturnStatus = EFI_INVALID_PARAMETER;
+ DEBUG(( DEBUG_VERBOSE, "%a - Bad Size. 0x%X <> 0x%X-0x%X\n", __FUNCTION__,
+ DataSize, ActivePolicy->MinSize, ActivePolicy->MaxSize ));
+ goto Exit;
+ }
+
+ // Check for attribute constraints.
+ if ((ActivePolicy->AttributesMustHave & Attributes) != ActivePolicy->AttributesMustHave ||
+ (ActivePolicy->AttributesCantHave & Attributes) != 0) {
+ ReturnStatus = EFI_INVALID_PARAMETER;
+ DEBUG(( DEBUG_VERBOSE, "%a - Bad Attributes. 0x%X <> 0x%X:0x%X\n", __FUNCTION__,
+ Attributes, ActivePolicy->AttributesMustHave, ActivePolicy->AttributesCantHave ));
+ goto Exit;
+ }
+ }
+
+ //
+ // Lock policy check.
+ //
+ // Check for immediate lock.
+ if (ActivePolicy->LockPolicyType == VARIABLE_POLICY_TYPE_LOCK_NOW) {
+ ReturnStatus = EFI_WRITE_PROTECTED;
+ goto Exit;
+ // Check for lock on create.
+ } else if (ActivePolicy->LockPolicyType == VARIABLE_POLICY_TYPE_LOCK_ON_CREATE) {
+ StateVarSize = 0;
+ Status = mGetVariableHelper( VariableName,
+ VendorGuid,
+ NULL,
+ &StateVarSize,
+ NULL );
+ if (Status == EFI_BUFFER_TOO_SMALL) {
+ ReturnStatus = EFI_WRITE_PROTECTED;
+ goto Exit;
+ }
+ // Check for lock on state variable.
+ } else if (ActivePolicy->LockPolicyType == VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE) {
+ StateVarPolicy = (VARIABLE_LOCK_ON_VAR_STATE_POLICY*)((UINT8*)ActivePolicy + sizeof(VARIABLE_POLICY_ENTRY));
+ StateVarName = (CHAR16*)((UINT8*)StateVarPolicy + sizeof(VARIABLE_LOCK_ON_VAR_STATE_POLICY));
+ StateVarSize = sizeof(StateVar);
+ Status = mGetVariableHelper( StateVarName,
+ &StateVarPolicy->Namespace,
+ NULL,
+ &StateVarSize,
+ &StateVar );
+
+ // If the variable was found, check the state. If matched, this variable is locked.
+ if (!EFI_ERROR( Status )) {
+ if (StateVar == StateVarPolicy->Value) {
+ ReturnStatus = EFI_WRITE_PROTECTED;
+ goto Exit;
+ }
+ // EFI_NOT_FOUND and EFI_BUFFER_TOO_SMALL indicate that the state doesn't match.
+ } else if (Status != EFI_NOT_FOUND && Status != EFI_BUFFER_TOO_SMALL) {
+ // We don't know what happened, but it isn't good.
+ ReturnStatus = EFI_ABORTED;
+ goto Exit;
+ }
+ }
+ }
+
+Exit:
+ DEBUG(( DEBUG_VERBOSE, "%a - Variable (%g:%s) returning %r.\n", __FUNCTION__, VendorGuid, VariableName, ReturnStatus ));
+ return ReturnStatus;
+}
+
+
+/**
+ 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.
+ @retval EFI_NOT_READY Library has not yet been initialized.
+
+**/
+EFI_STATUS
+EFIAPI
+DisableVariablePolicy (
+ VOID
+ )
+{
+ if (!IsVariablePolicyLibInitialized()) {
+ return EFI_NOT_READY;
+ }
+ if (mProtectionDisabled) {
+ return EFI_ALREADY_STARTED;
+ }
+ if (mInterfaceLocked) {
+ return EFI_WRITE_PROTECTED;
+ }
+ if (!PcdGetBool (PcdAllowVariablePolicyEnforcementDisable)) {
+ return EFI_WRITE_PROTECTED;
+ }
+ mProtectionDisabled = TRUE;
+ return EFI_SUCCESS;
+}
+
+
+/**
+ 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.
+ @retval EFI_NOT_READY Library has not yet been initialized.
+
+**/
+EFI_STATUS
+EFIAPI
+DumpVariablePolicy (
+ OUT UINT8 *Policy,
+ IN OUT UINT32 *Size
+ )
+{
+ if (!IsVariablePolicyLibInitialized()) {
+ return EFI_NOT_READY;
+ }
+
+ // Check the parameters.
+ if (Size == NULL || (*Size > 0 && Policy == NULL)) {
+ return EFI_INVALID_PARAMETER;
+ }
+
+ // Make sure the size is sufficient to hold the policy table.
+ if (*Size < mCurrentTableUsage) {
+ *Size = mCurrentTableUsage;
+ return EFI_BUFFER_TOO_SMALL;
+ }
+
+ // If we're still here, copy the table and bounce.
+ CopyMem( Policy, mPolicyTable, mCurrentTableUsage );
+ *Size = mCurrentTableUsage;
+
+ return EFI_SUCCESS;
+}
+
+
+/**
+ This API function returns whether or not the policy engine is
+ currently being enforced.
+
+ @retval TRUE
+ @retval FALSE
+ @retval FALSE Library has not yet been initialized.
+
+**/
+BOOLEAN
+EFIAPI
+IsVariablePolicyEnabled (
+ VOID
+ )
+{
+ if (!IsVariablePolicyLibInitialized()) {
+ return FALSE;
+ }
+ return !mProtectionDisabled;
+}
+
+
+/**
+ 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 EFI_NOT_READY Library has not yet been initialized.
+
+**/
+EFI_STATUS
+EFIAPI
+LockVariablePolicy (
+ VOID
+ )
+{
+ if (!IsVariablePolicyLibInitialized()) {
+ return EFI_NOT_READY;
+ }
+ if (mInterfaceLocked) {
+ return EFI_WRITE_PROTECTED;
+ }
+ mInterfaceLocked = TRUE;
+ return EFI_SUCCESS;
+}
+
+
+/**
+ This API function returns whether or not the policy interface is locked
+ for the remainder of the boot.
+
+ @retval TRUE
+ @retval FALSE
+ @retval FALSE Library has not yet been initialized.
+
+**/
+BOOLEAN
+EFIAPI
+IsVariablePolicyInterfaceLocked (
+ VOID
+ )
+{
+ if (!IsVariablePolicyLibInitialized()) {
+ return FALSE;
+ }
+ return mInterfaceLocked;
+}
+
+
+/**
+ This helper function initializes the library and sets
+ up any required internal structures or handlers.
+
+ Also registers the internal pointer for the GetVariable helper.
+
+ @param[in] GetVariableHelper A function pointer matching the EFI_GET_VARIABLE prototype that will be used to
+ check policy criteria that involve the existence of other variables.
+
+ @retval EFI_SUCCESS
+ @retval EFI_ALREADY_STARTED The initialize function has been called more than once without a call to
+ deinitialize.
+
+**/
+EFI_STATUS
+EFIAPI
+InitVariablePolicyLib (
+ IN EFI_GET_VARIABLE GetVariableHelper
+ )
+{
+ EFI_STATUS Status;
+
+ Status = EFI_SUCCESS;
+
+ if (mGetVariableHelper != NULL) {
+ return EFI_ALREADY_STARTED;
+ }
+
+ if (!EFI_ERROR( Status )) {
+ Status = VariablePolicyExtraInit();
+ }
+
+ if (!EFI_ERROR( Status )) {
+ // Save an internal pointer to the GetVariableHelper.
+ mGetVariableHelper = GetVariableHelper;
+
+ // Initialize the global state.
+ mInterfaceLocked = FALSE;
+ mProtectionDisabled = FALSE;
+ mPolicyTable = NULL;
+ mCurrentTableSize = 0;
+ mCurrentTableUsage = 0;
+ mCurrentTableCount = 0;
+ }
+
+ return Status;
+}
+
+
+/**
+ This helper function returns whether or not the library is currently initialized.
+
+ @retval TRUE
+ @retval FALSE
+
+**/
+BOOLEAN
+EFIAPI
+IsVariablePolicyLibInitialized (
+ VOID
+ )
+{
+ return (mGetVariableHelper != NULL);
+}
+
+
+/**
+ This helper function tears down the library.
+
+ Should generally only be used for test harnesses.
+
+ @retval EFI_SUCCESS
+ @retval EFI_NOT_READY Deinitialize was called without first calling initialize.
+
+**/
+EFI_STATUS
+EFIAPI
+DeinitVariablePolicyLib (
+ VOID
+ )
+{
+ EFI_STATUS Status;
+
+ Status = EFI_SUCCESS;
+
+ if (mGetVariableHelper == NULL) {
+ return EFI_NOT_READY;
+ }
+
+ if (!EFI_ERROR( Status )) {
+ Status = VariablePolicyExtraDeinit();
+ }
+
+ if (!EFI_ERROR( Status )) {
+ mGetVariableHelper = NULL;
+ mInterfaceLocked = FALSE;
+ mProtectionDisabled = FALSE;
+ mCurrentTableSize = 0;
+ mCurrentTableUsage = 0;
+ mCurrentTableCount = 0;
+
+ if (mPolicyTable != NULL) {
+ FreePool( mPolicyTable );
+ mPolicyTable = NULL;
+ }
+ }
+
+ return Status;
+}
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