/** @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/BaseLib.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 = AllocateRuntimePool (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", | |
__func__, | |
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", | |
__func__, | |
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", __func__, 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 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. | |
**/ | |
EFI_STATUS | |
EFIAPI | |
GetVariablePolicyInfo ( | |
IN CONST CHAR16 *VariableName, | |
IN CONST EFI_GUID *VendorGuid, | |
IN OUT UINTN *VariablePolicyVariableNameBufferSize OPTIONAL, | |
OUT VARIABLE_POLICY_ENTRY *VariablePolicy, | |
OUT CHAR16 *VariablePolicyVariableName OPTIONAL | |
) | |
{ | |
EFI_STATUS Status; | |
UINT8 MatchPriority; | |
UINTN LocalVariablePolicyVariableNameBufferSize; | |
UINTN RequiredVariablePolicyVariableNameBufferSize; | |
VARIABLE_POLICY_ENTRY *MatchPolicy; | |
Status = EFI_SUCCESS; | |
if (!IsVariablePolicyLibInitialized ()) { | |
return EFI_NOT_READY; | |
} | |
if ((VariableName == NULL) || (VendorGuid == NULL) || (VariablePolicy == NULL)) { | |
return EFI_INVALID_PARAMETER; | |
} | |
MatchPolicy = GetBestPolicyMatch ( | |
VariableName, | |
VendorGuid, | |
&MatchPriority | |
); | |
if (MatchPolicy != NULL) { | |
CopyMem (VariablePolicy, MatchPolicy, sizeof (*VariablePolicy)); | |
if (VariablePolicyVariableNameBufferSize == NULL) { | |
if (VariablePolicyVariableName != NULL) { | |
return EFI_INVALID_PARAMETER; | |
} | |
return Status; | |
} | |
if (MatchPolicy->Size != MatchPolicy->OffsetToName) { | |
if (MatchPolicy->Size < MatchPolicy->OffsetToName) { | |
ASSERT (MatchPolicy->Size > MatchPolicy->OffsetToName); | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
RequiredVariablePolicyVariableNameBufferSize = (UINTN)(MatchPolicy->Size - MatchPolicy->OffsetToName); | |
ASSERT (RequiredVariablePolicyVariableNameBufferSize > 0); | |
if (*VariablePolicyVariableNameBufferSize < RequiredVariablePolicyVariableNameBufferSize) { | |
// Let the caller get the size needed to hold the policy variable name | |
*VariablePolicyVariableNameBufferSize = RequiredVariablePolicyVariableNameBufferSize; | |
return EFI_BUFFER_TOO_SMALL; | |
} | |
if (VariablePolicyVariableName == NULL) { | |
// If the policy variable name size given is valid, then a valid policy variable name buffer should be provided | |
*VariablePolicyVariableNameBufferSize = RequiredVariablePolicyVariableNameBufferSize; | |
return EFI_INVALID_PARAMETER; | |
} | |
LocalVariablePolicyVariableNameBufferSize = *VariablePolicyVariableNameBufferSize; | |
// Actual string size should match expected string size | |
if ( | |
((StrnLenS (GET_POLICY_NAME (MatchPolicy), RequiredVariablePolicyVariableNameBufferSize) + 1) * sizeof (CHAR16)) | |
!= RequiredVariablePolicyVariableNameBufferSize) | |
{ | |
ASSERT_EFI_ERROR (EFI_BAD_BUFFER_SIZE); | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
*VariablePolicyVariableNameBufferSize = RequiredVariablePolicyVariableNameBufferSize; | |
Status = StrnCpyS ( | |
VariablePolicyVariableName, | |
LocalVariablePolicyVariableNameBufferSize / sizeof (CHAR16), | |
GET_POLICY_NAME (MatchPolicy), | |
RequiredVariablePolicyVariableNameBufferSize / sizeof (CHAR16) | |
); | |
ASSERT_EFI_ERROR (Status); | |
} else { | |
// A variable policy variable name is not present. Return values according to interface. | |
*VariablePolicyVariableNameBufferSize = 0; | |
} | |
return Status; | |
} | |
return EFI_NOT_FOUND; | |
} | |
/** | |
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. | |
**/ | |
EFI_STATUS | |
EFIAPI | |
GetLockOnVariableStateVariablePolicyInfo ( | |
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 | |
) | |
{ | |
EFI_STATUS Status; | |
UINT8 MatchPriority; | |
UINTN RequiredVariablePolicyVariableNameBufferSize; | |
UINTN RequiredVariableLockPolicyVariableNameBufferSize; | |
UINTN LocalVariablePolicyLockVariableNameBufferSize; | |
UINTN LockOnVarStatePolicyEndOffset; | |
CHAR16 *LocalVariableLockPolicyVariableName; | |
VARIABLE_LOCK_ON_VAR_STATE_POLICY *LocalLockOnVarStatePolicy; | |
VARIABLE_POLICY_ENTRY *MatchPolicy; | |
Status = EFI_SUCCESS; | |
if (!IsVariablePolicyLibInitialized ()) { | |
return EFI_NOT_READY; | |
} | |
if ((VariableName == NULL) || (VendorGuid == NULL) || (VariablePolicy == NULL)) { | |
return EFI_INVALID_PARAMETER; | |
} | |
MatchPolicy = GetBestPolicyMatch ( | |
VariableName, | |
VendorGuid, | |
&MatchPriority | |
); | |
if (MatchPolicy != NULL) { | |
if (MatchPolicy->LockPolicyType != VARIABLE_POLICY_TYPE_LOCK_ON_VAR_STATE) { | |
return EFI_NOT_FOUND; | |
} | |
Status = SafeUintnAdd ( | |
sizeof (VARIABLE_POLICY_ENTRY), | |
sizeof (VARIABLE_LOCK_ON_VAR_STATE_POLICY), | |
&LockOnVarStatePolicyEndOffset | |
); | |
if (EFI_ERROR (Status) || (LockOnVarStatePolicyEndOffset > (UINTN)MatchPolicy->Size)) { | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
LocalLockOnVarStatePolicy = (VARIABLE_LOCK_ON_VAR_STATE_POLICY *)(MatchPolicy + 1); | |
CopyMem (VariablePolicy, LocalLockOnVarStatePolicy, sizeof (*LocalLockOnVarStatePolicy)); | |
if ((VariableLockPolicyVariableNameBufferSize == NULL)) { | |
if (VariableLockPolicyVariableName != NULL) { | |
return EFI_INVALID_PARAMETER; | |
} | |
return Status; | |
} | |
// The name offset should be less than or equal to the total policy size. | |
if (MatchPolicy->Size < MatchPolicy->OffsetToName) { | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
RequiredVariablePolicyVariableNameBufferSize = (UINTN)(MatchPolicy->Size - MatchPolicy->OffsetToName); | |
RequiredVariableLockPolicyVariableNameBufferSize = MatchPolicy->Size - | |
(LockOnVarStatePolicyEndOffset + RequiredVariablePolicyVariableNameBufferSize); | |
LocalVariablePolicyLockVariableNameBufferSize = *VariableLockPolicyVariableNameBufferSize; | |
*VariableLockPolicyVariableNameBufferSize = RequiredVariableLockPolicyVariableNameBufferSize; | |
if (LocalVariablePolicyLockVariableNameBufferSize < RequiredVariableLockPolicyVariableNameBufferSize) { | |
// Let the caller get the size needed to hold the policy variable name | |
return EFI_BUFFER_TOO_SMALL; | |
} | |
if (VariableLockPolicyVariableName == NULL) { | |
// If the policy variable name size given is valid, then a valid policy variable name buffer should be provided | |
return EFI_INVALID_PARAMETER; | |
} | |
if (RequiredVariableLockPolicyVariableNameBufferSize == 0) { | |
return Status; | |
} | |
LocalVariableLockPolicyVariableName = (CHAR16 *)((UINT8 *)LocalLockOnVarStatePolicy + sizeof (*LocalLockOnVarStatePolicy)); | |
*VariableLockPolicyVariableNameBufferSize = RequiredVariableLockPolicyVariableNameBufferSize; | |
// Actual string size should match expected string size (if a variable name is present) | |
if ( | |
(RequiredVariablePolicyVariableNameBufferSize > 0) && | |
(((StrnLenS (GET_POLICY_NAME (MatchPolicy), RequiredVariablePolicyVariableNameBufferSize) + 1) * sizeof (CHAR16)) != | |
RequiredVariablePolicyVariableNameBufferSize)) | |
{ | |
ASSERT_EFI_ERROR (EFI_BAD_BUFFER_SIZE); | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
// Actual string size should match expected string size (if here, variable lock variable name is present) | |
if ( | |
((StrnLenS (LocalVariableLockPolicyVariableName, RequiredVariableLockPolicyVariableNameBufferSize) + 1) * sizeof (CHAR16)) != | |
RequiredVariableLockPolicyVariableNameBufferSize) | |
{ | |
ASSERT_EFI_ERROR (EFI_BAD_BUFFER_SIZE); | |
return EFI_BAD_BUFFER_SIZE; | |
} | |
Status = StrnCpyS ( | |
VariableLockPolicyVariableName, | |
LocalVariablePolicyLockVariableNameBufferSize / sizeof (CHAR16), | |
LocalVariableLockPolicyVariableName, | |
RequiredVariableLockPolicyVariableNameBufferSize / sizeof (CHAR16) | |
); | |
ASSERT_EFI_ERROR (Status); | |
return Status; | |
} | |
return EFI_NOT_FOUND; | |
} | |
/** | |
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; | |
} |