1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
|
/** @file -- VariablePolicySmmDxe.c
This protocol allows communication with Variable Policy Engine.
Copyright (c) Microsoft Corporation.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Library/UefiLib.h>
#include <Library/DebugLib.h>
#include <Library/SafeIntLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Protocol/VariablePolicy.h>
#include <Protocol/MmCommunication2.h>
#include <Guid/VarCheckPolicyMmi.h>
#include "Variable.h"
EDKII_VARIABLE_POLICY_PROTOCOL mVariablePolicyProtocol;
EFI_MM_COMMUNICATION2_PROTOCOL *mMmCommunication;
VOID *mMmCommunicationBuffer;
UINTN mMmCommunicationBufferSize;
EFI_LOCK mMmCommunicationLock;
/**
Internal helper function to consolidate communication method.
@param[in,out] CommBuffer
@param[in,out] CommSize Size of the CommBuffer.
@retval EFI_STATUS Result from communication method.
**/
STATIC
EFI_STATUS
InternalMmCommunicate (
IN OUT VOID *CommBuffer,
IN OUT UINTN *CommSize
)
{
EFI_STATUS Status;
if ((CommBuffer == NULL) || (CommSize == NULL)) {
return EFI_INVALID_PARAMETER;
}
Status = mMmCommunication->Communicate (mMmCommunication, CommBuffer, CommBuffer, CommSize);
return Status;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolDisableVariablePolicy (
VOID
)
{
EFI_STATUS Status;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
UINTN BufferSize;
// Check the PCD for convenience.
// This would also be rejected by the lib, but why go to MM if we don't have to?
if (!PcdGetBool (PcdAllowVariablePolicyEnforcementDisable)) {
return EFI_WRITE_PROTECTED;
}
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
// Set up the MM communication.
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = VAR_CHECK_POLICY_COMMAND_DISABLE;
Status = InternalMmCommunicate (CommHeader, &BufferSize);
DEBUG ((DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __func__, Status));
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
return (EFI_ERROR (Status)) ? Status : PolicyHeader->Result;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolIsVariablePolicyEnabled (
OUT BOOLEAN *State
)
{
EFI_STATUS Status;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
VAR_CHECK_POLICY_COMM_IS_ENABLED_PARAMS *CommandParams;
UINTN BufferSize;
if (State == NULL) {
return EFI_INVALID_PARAMETER;
}
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
// Set up the MM communication.
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
CommandParams = (VAR_CHECK_POLICY_COMM_IS_ENABLED_PARAMS *)(PolicyHeader + 1);
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = VAR_CHECK_POLICY_COMMAND_IS_ENABLED;
Status = InternalMmCommunicate (CommHeader, &BufferSize);
DEBUG ((DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __func__, Status));
if (!EFI_ERROR (Status)) {
Status = PolicyHeader->Result;
*State = CommandParams->State;
}
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
return Status;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolRegisterVariablePolicy (
IN CONST VARIABLE_POLICY_ENTRY *NewPolicy
)
{
EFI_STATUS Status;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
VOID *PolicyBuffer;
UINTN BufferSize;
UINTN RequiredSize;
if (NewPolicy == NULL) {
return EFI_INVALID_PARAMETER;
}
// First, make sure that the required size does not exceed the capabilities
// of the MmCommunication buffer.
RequiredSize = OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data) + sizeof (VAR_CHECK_POLICY_COMM_HEADER);
Status = SafeUintnAdd (RequiredSize, NewPolicy->Size, &RequiredSize);
if (EFI_ERROR (Status) || (RequiredSize > mMmCommunicationBufferSize)) {
DEBUG ((
DEBUG_ERROR,
"%a - Policy too large for buffer! %r, %d > %d \n",
__func__,
Status,
RequiredSize,
mMmCommunicationBufferSize
));
return EFI_OUT_OF_RESOURCES;
}
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
// Set up the MM communication.
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
PolicyBuffer = (VOID *)(PolicyHeader + 1);
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = VAR_CHECK_POLICY_COMMAND_REGISTER;
// Copy the policy into place. This copy is safe because we've already tested above.
CopyMem (PolicyBuffer, NewPolicy, NewPolicy->Size);
Status = InternalMmCommunicate (CommHeader, &BufferSize);
DEBUG ((DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __func__, Status));
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
return (EFI_ERROR (Status)) ? Status : PolicyHeader->Result;
}
/**
This helper function takes care of the overhead of formatting, sending, and interpreting
the results for a single DumpVariablePolicy request.
@param[in] PageRequested The page of the paginated results from MM. 0 for metadata.
@param[out] TotalSize The total size of the entire buffer. Returned as part of metadata.
@param[out] PageSize The size of the current page being returned. Not valid as part of metadata.
@param[out] HasMore A flag indicating whether there are more pages after this one.
@param[out] Buffer The start of the current page from MM.
@retval EFI_SUCCESS Output params have been updated (either metadata or dump page).
@retval EFI_INVALID_PARAMETER One of the output params is NULL.
@retval Others Response from MM handler.
**/
STATIC
EFI_STATUS
DumpVariablePolicyHelper (
IN UINT32 PageRequested,
OUT UINT32 *TotalSize,
OUT UINT32 *PageSize,
OUT BOOLEAN *HasMore,
OUT UINT8 **Buffer
)
{
EFI_STATUS Status;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
VAR_CHECK_POLICY_COMM_DUMP_PARAMS *CommandParams;
UINTN BufferSize;
if ((TotalSize == NULL) || (PageSize == NULL) || (HasMore == NULL) || (Buffer == NULL)) {
return EFI_INVALID_PARAMETER;
}
// Set up the MM communication.
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
CommandParams = (VAR_CHECK_POLICY_COMM_DUMP_PARAMS *)(PolicyHeader + 1);
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = VAR_CHECK_POLICY_COMMAND_DUMP;
CommandParams->PageRequested = PageRequested;
Status = InternalMmCommunicate (CommHeader, &BufferSize);
DEBUG ((DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __func__, Status));
if (!EFI_ERROR (Status)) {
Status = PolicyHeader->Result;
*TotalSize = CommandParams->TotalSize;
*PageSize = CommandParams->PageSize;
*HasMore = CommandParams->HasMore;
*Buffer = (UINT8 *)(CommandParams + 1);
}
return Status;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolDumpVariablePolicy (
OUT UINT8 *Policy OPTIONAL,
IN OUT UINT32 *Size
)
{
EFI_STATUS Status;
UINT8 *Source;
UINT8 *Destination;
UINT32 PolicySize;
UINT32 PageSize;
BOOLEAN HasMore;
UINT32 PageIndex;
if ((Size == NULL) || ((*Size > 0) && (Policy == NULL))) {
return EFI_INVALID_PARAMETER;
}
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
// Repeat this whole process until we either have a failure case or get the entire buffer.
do {
// First, we must check the zero page to determine the buffer size and
// reset the internal state.
PolicySize = 0;
PageSize = 0;
HasMore = FALSE;
Status = DumpVariablePolicyHelper (0, &PolicySize, &PageSize, &HasMore, &Source);
if (EFI_ERROR (Status)) {
break;
}
// If we're good, we can at least check the required size now.
if (*Size < PolicySize) {
*Size = PolicySize;
Status = EFI_BUFFER_TOO_SMALL;
break;
}
// On further thought, let's update the size either way.
*Size = PolicySize;
// And get ready to ROCK.
Destination = Policy;
// Keep looping and copying until we're either done or freak out.
for (PageIndex = 1; !EFI_ERROR (Status) && HasMore && PageIndex < MAX_UINT32; PageIndex++) {
Status = DumpVariablePolicyHelper (PageIndex, &PolicySize, &PageSize, &HasMore, &Source);
if (!EFI_ERROR (Status)) {
CopyMem (Destination, Source, PageSize);
Destination += PageSize;
}
}
// Next, we check to see whether
} while (Status == EFI_TIMEOUT);
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
// There's currently no use for this, but it shouldn't be hard to implement.
return Status;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolLockVariablePolicy (
VOID
)
{
EFI_STATUS Status;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
UINTN BufferSize;
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
// Set up the MM communication.
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = VAR_CHECK_POLICY_COMMAND_LOCK;
Status = InternalMmCommunicate (CommHeader, &BufferSize);
DEBUG ((DEBUG_VERBOSE, "%a - MmCommunication returned %r.\n", __func__, Status));
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
return (EFI_ERROR (Status)) ? Status : PolicyHeader->Result;
}
/**
Internal implementation to retrieve variable information for a given UEFI variable that is shared
between different policy types.
Currently, the two policy structure types supported (and all that is defined) are VARIABLE_POLICY_ENTRY
and VARIABLE_LOCK_ON_VAR_STATE_POLICY.
@param[in] Command The command value to use in the communicate call.
@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. It can also be returned if the Command value provided is invalid.
@retval EFI_NOT_FOUND A variable policy was not found for the given UEFI variable name and vendor GUID.
**/
STATIC
EFI_STATUS
InternalProtocolGetVariablePolicyInfo (
IN UINT32 Command,
IN CONST CHAR16 *VariableName,
IN CONST EFI_GUID *VendorGuid,
IN OUT UINTN *VariablePolicyVariableNameBufferSize, OPTIONAL
OUT VOID *VariablePolicy,
OUT CHAR16 *VariablePolicyVariableName OPTIONAL
)
{
EFI_STATUS Status;
CHAR16 *OutputVariableName;
EFI_MM_COMMUNICATE_HEADER *CommHeader;
VAR_CHECK_POLICY_COMM_HEADER *PolicyHeader;
VAR_CHECK_POLICY_COMM_GET_INFO_PARAMS *CommandParams;
UINTN AllowedOutputVariableNameSize;
UINTN BufferSize;
UINTN VariableNameSize;
if ((VariableName == NULL) || (VendorGuid == NULL) || (VariablePolicy == NULL)) {
return EFI_INVALID_PARAMETER;
}
switch (Command) {
case VAR_CHECK_POLICY_COMMAND_GET_INFO:
case VAR_CHECK_POLICY_COMMAND_GET_LOCK_VAR_STATE_INFO:
break;
default:
return EFI_INVALID_PARAMETER;
}
AcquireLockOnlyAtBootTime (&mMmCommunicationLock);
VariableNameSize = StrnSizeS (
VariableName,
(VAR_CHECK_POLICY_MM_GET_INFO_BUFFER_SIZE - VAR_CHECK_POLICY_COMM_GET_INFO_PARAMS_END)
);
if (VariableNameSize >= (VAR_CHECK_POLICY_MM_GET_INFO_BUFFER_SIZE - VAR_CHECK_POLICY_COMM_GET_INFO_PARAMS_END)) {
Status = EFI_INVALID_PARAMETER;
goto Done;
}
if ((VariablePolicyVariableName != NULL) && (VariablePolicyVariableNameBufferSize == NULL)) {
return EFI_INVALID_PARAMETER;
goto Done;
}
BufferSize = mMmCommunicationBufferSize;
CommHeader = mMmCommunicationBuffer;
Status = SafeUintnSub (
VAR_CHECK_POLICY_MM_GET_INFO_BUFFER_SIZE,
VariableNameSize,
&AllowedOutputVariableNameSize
);
if (EFI_ERROR (Status)) {
Status = EFI_INVALID_PARAMETER;
goto Done;
}
if (VariablePolicyVariableNameBufferSize != NULL) {
AllowedOutputVariableNameSize = MIN (AllowedOutputVariableNameSize, *VariablePolicyVariableNameBufferSize);
} else {
AllowedOutputVariableNameSize = 0;
}
PolicyHeader = (VAR_CHECK_POLICY_COMM_HEADER *)&CommHeader->Data;
CommandParams = (VAR_CHECK_POLICY_COMM_GET_INFO_PARAMS *)(PolicyHeader + 1);
CopyGuid (&CommHeader->HeaderGuid, &gVarCheckPolicyLibMmiHandlerGuid);
CommHeader->MessageLength = BufferSize - OFFSET_OF (EFI_MM_COMMUNICATE_HEADER, Data);
PolicyHeader->Signature = VAR_CHECK_POLICY_COMM_SIG;
PolicyHeader->Revision = VAR_CHECK_POLICY_COMM_REVISION;
PolicyHeader->Command = Command;
ZeroMem ((VOID *)&CommandParams->OutputPolicyEntry, sizeof (CommandParams->OutputPolicyEntry));
CopyGuid (&CommandParams->InputVendorGuid, VendorGuid);
Status = SafeUintnToUint32 (VariableNameSize, &CommandParams->InputVariableNameSize);
if (EFI_ERROR (Status)) {
Status = EFI_INVALID_PARAMETER;
goto Done;
}
Status = SafeUintnToUint32 (AllowedOutputVariableNameSize, &CommandParams->OutputVariableNameSize);
if (EFI_ERROR (Status)) {
Status = EFI_INVALID_PARAMETER;
goto Done;
}
if (AllowedOutputVariableNameSize > 0) {
Status = StrnCpyS (
CommandParams->InputVariableName,
AllowedOutputVariableNameSize / sizeof (CHAR16),
VariableName,
(UINTN)CommandParams->InputVariableNameSize / sizeof (CHAR16)
);
ASSERT_EFI_ERROR (Status);
}
Status = InternalMmCommunicate (CommHeader, &BufferSize);
if (Status == EFI_SUCCESS) {
CopyMem (
VariablePolicy,
(VOID *)&CommandParams->OutputPolicyEntry,
(Command == VAR_CHECK_POLICY_COMMAND_GET_INFO) ?
sizeof (CommandParams->OutputPolicyEntry.VariablePolicy) :
sizeof (CommandParams->OutputPolicyEntry.LockOnVarStatePolicy)
);
if (VariablePolicyVariableNameBufferSize == NULL) {
if (VariablePolicyVariableName != NULL) {
Status = EFI_INVALID_PARAMETER;
}
goto Done;
}
if (PolicyHeader->Result == EFI_BUFFER_TOO_SMALL) {
*VariablePolicyVariableNameBufferSize = (UINTN)CommandParams->OutputVariableNameSize;
goto Done;
}
if (PolicyHeader->Result == EFI_SUCCESS) {
if (CommandParams->OutputVariableNameSize > 0) {
Status = SafeUintnAdd (
((UINTN)CommandParams + VAR_CHECK_POLICY_COMM_GET_INFO_PARAMS_END),
(UINTN)CommandParams->InputVariableNameSize,
(UINTN *)&OutputVariableName
);
if (EFI_ERROR (Status)) {
Status = EFI_BAD_BUFFER_SIZE;
goto Done;
}
Status = StrnCpyS (
VariablePolicyVariableName,
*VariablePolicyVariableNameBufferSize / sizeof (CHAR16),
OutputVariableName,
(UINTN)CommandParams->OutputVariableNameSize
);
ASSERT_EFI_ERROR (Status);
*VariablePolicyVariableNameBufferSize = (UINTN)CommandParams->OutputVariableNameSize;
} else {
// A variable policy variable name is not present. Return values according to interface.
*VariablePolicyVariableNameBufferSize = 0;
}
}
}
Done:
ReleaseLockOnlyAtBootTime (&mMmCommunicationLock);
return (EFI_ERROR (Status)) ? Status : PolicyHeader->Result;
}
/**
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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolGetVariablePolicyInfo (
IN CONST CHAR16 *VariableName,
IN CONST EFI_GUID *VendorGuid,
IN OUT UINTN *VariablePolicyVariableNameBufferSize, OPTIONAL
OUT VARIABLE_POLICY_ENTRY *VariablePolicy,
OUT CHAR16 *VariablePolicyVariableName OPTIONAL
)
{
return InternalProtocolGetVariablePolicyInfo (
VAR_CHECK_POLICY_COMMAND_GET_INFO,
VariableName,
VendorGuid,
VariablePolicyVariableNameBufferSize,
VariablePolicy,
VariablePolicyVariableName
);
}
/**
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
P 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.
**/
STATIC
EFI_STATUS
EFIAPI
ProtocolGetLockOnVariableStateVariablePolicyInfo (
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
)
{
return InternalProtocolGetVariablePolicyInfo (
VAR_CHECK_POLICY_COMMAND_GET_LOCK_VAR_STATE_INFO,
VariableName,
VendorGuid,
VariableLockPolicyVariableNameBufferSize,
VariablePolicy,
VariableLockPolicyVariableName
);
}
/**
This helper function locates the shared comm buffer and assigns it to input pointers.
@param[in,out] BufferSize On input, the minimum buffer size required INCLUDING the MM communicate header.
On output, the size of the matching buffer found.
@param[out] LocatedBuffer A pointer to the matching buffer.
@retval EFI_SUCCESS
@retval EFI_INVALID_PARAMETER One of the output pointers was NULL.
@retval EFI_OUT_OF_RESOURCES Not enough memory to allocate a comm buffer.
**/
STATIC
EFI_STATUS
InitMmCommonCommBuffer (
IN OUT UINTN *BufferSize,
OUT VOID **LocatedBuffer
)
{
EFI_STATUS Status;
Status = EFI_SUCCESS;
// Make sure that we're working with good pointers.
if ((BufferSize == NULL) || (LocatedBuffer == NULL)) {
return EFI_INVALID_PARAMETER;
}
// Allocate the runtime memory for the comm buffer.
*LocatedBuffer = AllocateRuntimePool (*BufferSize);
if (*LocatedBuffer == NULL) {
Status = EFI_OUT_OF_RESOURCES;
*BufferSize = 0;
}
EfiInitializeLock (&mMmCommunicationLock, TPL_NOTIFY);
return Status;
}
/**
Convert internal pointer addresses to virtual addresses.
@param[in] Event Event whose notification function is being invoked.
@param[in] Context The pointer to the notification function's context, which
is implementation-dependent.
**/
STATIC
VOID
EFIAPI
VariablePolicyVirtualAddressCallback (
IN EFI_EVENT Event,
IN VOID *Context
)
{
EfiConvertPointer (0, (VOID **)&mMmCommunication);
EfiConvertPointer (0, (VOID **)&mMmCommunicationBuffer);
}
/**
The driver's entry point.
@param[in] ImageHandle The firmware allocated handle for the EFI image.
@param[in] SystemTable A pointer to the EFI System Table.
@retval EFI_SUCCESS The entry point executed successfully.
@retval other Some error occured when executing this entry point.
**/
EFI_STATUS
EFIAPI
VariablePolicySmmDxeMain (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
BOOLEAN ProtocolInstalled;
BOOLEAN VirtualAddressChangeRegistered;
EFI_EVENT VirtualAddressChangeEvent;
Status = EFI_SUCCESS;
ProtocolInstalled = FALSE;
VirtualAddressChangeRegistered = FALSE;
// Update the minimum buffer size.
mMmCommunicationBufferSize = VAR_CHECK_POLICY_MM_COMM_BUFFER_SIZE;
// Locate the shared comm buffer to use for sending MM commands.
Status = InitMmCommonCommBuffer (&mMmCommunicationBufferSize, &mMmCommunicationBuffer);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a - Failed to locate a viable MM comm buffer! %r\n", __func__, Status));
ASSERT_EFI_ERROR (Status);
return Status;
}
// Locate the MmCommunication protocol.
Status = gBS->LocateProtocol (&gEfiMmCommunication2ProtocolGuid, NULL, (VOID **)&mMmCommunication);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a - Failed to locate MmCommunication protocol! %r\n", __func__, Status));
ASSERT_EFI_ERROR (Status);
return Status;
}
// Configure the VariablePolicy protocol structure.
mVariablePolicyProtocol.Revision = EDKII_VARIABLE_POLICY_PROTOCOL_REVISION;
mVariablePolicyProtocol.DisableVariablePolicy = ProtocolDisableVariablePolicy;
mVariablePolicyProtocol.IsVariablePolicyEnabled = ProtocolIsVariablePolicyEnabled;
mVariablePolicyProtocol.RegisterVariablePolicy = ProtocolRegisterVariablePolicy;
mVariablePolicyProtocol.DumpVariablePolicy = ProtocolDumpVariablePolicy;
mVariablePolicyProtocol.LockVariablePolicy = ProtocolLockVariablePolicy;
mVariablePolicyProtocol.GetVariablePolicyInfo = ProtocolGetVariablePolicyInfo;
mVariablePolicyProtocol.GetLockOnVariableStateVariablePolicyInfo = ProtocolGetLockOnVariableStateVariablePolicyInfo;
// Register all the protocols and return the status.
Status = gBS->InstallMultipleProtocolInterfaces (
&ImageHandle,
&gEdkiiVariablePolicyProtocolGuid,
&mVariablePolicyProtocol,
NULL
);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a - Failed to install protocol! %r\n", __func__, Status));
goto Exit;
} else {
ProtocolInstalled = TRUE;
}
// Normally, we might want to register a callback
// to lock the interface, but this is integrated
// into the existing callbacks in VaraiableSmm.c
// and VariableDxe.c.
//
// Register a VirtualAddressChange callback for the MmComm protocol and Comm buffer.
Status = gBS->CreateEventEx (
EVT_NOTIFY_SIGNAL,
TPL_NOTIFY,
VariablePolicyVirtualAddressCallback,
NULL,
&gEfiEventVirtualAddressChangeGuid,
&VirtualAddressChangeEvent
);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_ERROR, "%a - Failed to create VirtualAddressChange event! %r\n", __func__, Status));
goto Exit;
} else {
VirtualAddressChangeRegistered = TRUE;
}
Exit:
//
// If we're about to return a failed status (and unload this driver), we must first undo anything that
// has been successfully done.
if (EFI_ERROR (Status)) {
if (ProtocolInstalled) {
gBS->UninstallProtocolInterface (&ImageHandle, &gEdkiiVariablePolicyProtocolGuid, &mVariablePolicyProtocol);
}
if (VirtualAddressChangeRegistered) {
gBS->CloseEvent (VirtualAddressChangeEvent);
}
}
return Status;
}
|