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MdeModulePkg/VariablePolicy: Add more granular variable policy querying

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Introduces two new APIs to EDKII_VARIABLE_POLICY_PROTOCOL:
  1. GetVariablePolicyInfo()
  2. GetLockOnVariableStateVariablePolicyInfo()

These allow a caller to retrieve policy information associated with
a UEFI variable given the variable name and vendor GUID.

GetVariablePolicyInfo() - Returns the variable policy applied to the
UEFI variable. If the variable policy is applied toward an individual
UEFI variable, that name can optionally be returned.

GetLockOnVariableStateVariablePolicyInfo() - Returns the Lock on
Variable State policy applied to the UEFI variable. If the Lock on
Variable State policy is applied to a specific variable name, that
name can optionally be returned.

These functions can be useful for a variety of purposes such as
auditing, testing, and functional flows.

Also fixed some variable name typos in code touched by the changes.

Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Message-Id: <20231030203112.736-2-mikuback@linux.microsoft.com>
This commit is contained in:
Michael Kubacki
2023-10-30 16:31:09 -04:00
committed by mergify[bot]
parent 8e74629070
commit f3b2187d55
8 changed files with 1062 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

304
MdeModulePkg/Library/VariablePolicyLib/VariablePolicyLib.c
View File

@@ -8,6 +8,7 @@ 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>
@@ -684,6 +685,309 @@ DumpVariablePolicy (
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.