1 /** @file 2 TCG MOR (Memory Overwrite Request) Lock Control support (SMM version). 3 4 This module initilizes MemoryOverwriteRequestControlLock variable. 5 This module adds Variable Hook and check MemoryOverwriteRequestControlLock. 6 7 Copyright (c) 2016, Intel Corporation. All rights reserved.<BR> 8 This program and the accompanying materials 9 are licensed and made available under the terms and conditions of the BSD License 10 which accompanies this distribution. The full text of the license may be found at 11 http://opensource.org/licenses/bsd-license.php 12 13 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 14 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 15 16 **/ 17 18 #include <PiDxe.h> 19 #include <Guid/MemoryOverwriteControl.h> 20 #include <IndustryStandard/MemoryOverwriteRequestControlLock.h> 21 #include <Library/DebugLib.h> 22 #include <Library/BaseLib.h> 23 #include <Library/BaseMemoryLib.h> 24 #include "Variable.h" 25 26 typedef struct { 27 CHAR16 *VariableName; 28 EFI_GUID *VendorGuid; 29 } VARIABLE_TYPE; 30 31 VARIABLE_TYPE mMorVariableType[] = { 32 {MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME, &gEfiMemoryOverwriteControlDataGuid}, 33 {MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME, &gEfiMemoryOverwriteRequestControlLockGuid}, 34 }; 35 36 #define MOR_LOCK_DATA_UNLOCKED 0x0 37 #define MOR_LOCK_DATA_LOCKED_WITHOUT_KEY 0x1 38 #define MOR_LOCK_DATA_LOCKED_WITH_KEY 0x2 39 40 #define MOR_LOCK_V1_SIZE 1 41 #define MOR_LOCK_V2_KEY_SIZE 8 42 43 typedef enum { 44 MorLockStateUnlocked = 0, 45 MorLockStateLocked = 1, 46 } MOR_LOCK_STATE; 47 48 UINT8 mMorLockKey[MOR_LOCK_V2_KEY_SIZE]; 49 BOOLEAN mMorLockKeyEmpty = TRUE; 50 BOOLEAN mMorLockPassThru = FALSE; 51 MOR_LOCK_STATE mMorLockState = MorLockStateUnlocked; 52 53 /** 54 Returns if this is MOR related variable. 55 56 @param VariableName the name of the vendor's variable, it's a Null-Terminated Unicode String 57 @param VendorGuid Unify identifier for vendor. 58 59 @retval TRUE The variable is MOR related. 60 @retval FALSE The variable is NOT MOR related. 61 **/ 62 BOOLEAN 63 IsAnyMorVariable ( 64 IN CHAR16 *VariableName, 65 IN EFI_GUID *VendorGuid 66 ) 67 { 68 UINTN Index; 69 70 for (Index = 0; Index < sizeof(mMorVariableType)/sizeof(mMorVariableType[0]); Index++) { 71 if ((StrCmp (VariableName, mMorVariableType[Index].VariableName) == 0) && 72 (CompareGuid (VendorGuid, mMorVariableType[Index].VendorGuid))) { 73 return TRUE; 74 } 75 } 76 return FALSE; 77 } 78 79 /** 80 Returns if this is MOR lock variable. 81 82 @param VariableName the name of the vendor's variable, it's a Null-Terminated Unicode String 83 @param VendorGuid Unify identifier for vendor. 84 85 @retval TRUE The variable is MOR lock variable. 86 @retval FALSE The variable is NOT MOR lock variable. 87 **/ 88 BOOLEAN 89 IsMorLockVariable ( 90 IN CHAR16 *VariableName, 91 IN EFI_GUID *VendorGuid 92 ) 93 { 94 if ((StrCmp (VariableName, MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME) == 0) && 95 (CompareGuid (VendorGuid, &gEfiMemoryOverwriteRequestControlLockGuid))) { 96 return TRUE; 97 } 98 return FALSE; 99 } 100 101 /** 102 Set MOR lock variable. 103 104 @param Data MOR Lock variable data. 105 106 @retval EFI_SUCCESS The firmware has successfully stored the variable and its data as 107 defined by the Attributes. 108 @retval EFI_INVALID_PARAMETER An invalid combination of attribute bits was supplied, or the 109 DataSize exceeds the maximum allowed. 110 @retval EFI_INVALID_PARAMETER VariableName is an empty Unicode string. 111 @retval EFI_OUT_OF_RESOURCES Not enough storage is available to hold the variable and its data. 112 @retval EFI_DEVICE_ERROR The variable could not be saved due to a hardware failure. 113 @retval EFI_WRITE_PROTECTED The variable in question is read-only. 114 @retval EFI_WRITE_PROTECTED The variable in question cannot be deleted. 115 @retval EFI_SECURITY_VIOLATION The variable could not be written due to EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS 116 set but the AuthInfo does NOT pass the validation check carried 117 out by the firmware. 118 @retval EFI_NOT_FOUND The variable trying to be updated or deleted was not found. 119 **/ 120 EFI_STATUS 121 SetMorLockVariable ( 122 IN UINT8 Data 123 ) 124 { 125 EFI_STATUS Status; 126 127 mMorLockPassThru = TRUE; 128 Status = VariableServiceSetVariable ( 129 MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME, 130 &gEfiMemoryOverwriteRequestControlLockGuid, 131 EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS, 132 sizeof(Data), 133 &Data 134 ); 135 mMorLockPassThru = FALSE; 136 return Status; 137 } 138 139 /** 140 This service is an MorLock checker handler for the SetVariable(). 141 142 @param VariableName the name of the vendor's variable, as a 143 Null-Terminated Unicode String 144 @param VendorGuid Unify identifier for vendor. 145 @param Attributes Point to memory location to return the attributes of variable. If the point 146 is NULL, the parameter would be ignored. 147 @param DataSize The size in bytes of Data-Buffer. 148 @param Data Point to the content of the variable. 149 150 @retval EFI_SUCCESS The MorLock check pass, and Variable driver can store the variable data. 151 @retval EFI_INVALID_PARAMETER The MorLock data or data size or attributes is not allowed. 152 @retval EFI_ACCESS_DENIED The MorLock is locked. 153 @retval EFI_WRITE_PROTECTED The MorLock deletion is not allowed. 154 @retval EFI_ALREADY_STARTED The MorLock variable is handled inside this function. 155 Variable driver can just return EFI_SUCCESS. 156 **/ 157 EFI_STATUS 158 SetVariableCheckHandlerMorLock ( 159 IN CHAR16 *VariableName, 160 IN EFI_GUID *VendorGuid, 161 IN UINT32 Attributes, 162 IN UINTN DataSize, 163 IN VOID *Data 164 ) 165 { 166 EFI_STATUS Status; 167 168 // 169 // Basic Check 170 // 171 if (Attributes == 0 || DataSize == 0 || Data == NULL) { 172 return EFI_WRITE_PROTECTED; 173 } 174 175 if ((Attributes != (EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS)) || 176 ((DataSize != MOR_LOCK_V1_SIZE) && (DataSize != MOR_LOCK_V2_KEY_SIZE))) { 177 return EFI_INVALID_PARAMETER; 178 } 179 180 // 181 // Do not check if the request is passthru. 182 // 183 if (mMorLockPassThru) { 184 return EFI_SUCCESS; 185 } 186 187 if (mMorLockState == MorLockStateUnlocked) { 188 // 189 // In Unlocked State 190 // 191 if (DataSize == MOR_LOCK_V1_SIZE) { 192 // 193 // V1 - lock permanently 194 // 195 if (*(UINT8 *)Data == MOR_LOCK_DATA_UNLOCKED) { 196 // 197 // Unlock 198 // 199 Status = SetMorLockVariable (MOR_LOCK_DATA_UNLOCKED); 200 if (!EFI_ERROR (Status)) { 201 // 202 // return EFI_ALREADY_STARTED to skip variable set. 203 // 204 return EFI_ALREADY_STARTED; 205 } else { 206 // 207 // SetVar fail 208 // 209 return Status; 210 } 211 } else if (*(UINT8 *)Data == MOR_LOCK_DATA_LOCKED_WITHOUT_KEY) { 212 // 213 // Lock without key 214 // 215 Status = SetMorLockVariable (MOR_LOCK_DATA_LOCKED_WITHOUT_KEY); 216 if (!EFI_ERROR (Status)) { 217 // 218 // Lock success 219 // 220 mMorLockState = MorLockStateLocked; 221 // 222 // return EFI_ALREADY_STARTED to skip variable set. 223 // 224 return EFI_ALREADY_STARTED; 225 } else { 226 // 227 // SetVar fail 228 // 229 return Status; 230 } 231 } else { 232 return EFI_INVALID_PARAMETER; 233 } 234 } else if (DataSize == MOR_LOCK_V2_KEY_SIZE) { 235 // 236 // V2 lock and provision the key 237 // 238 239 // 240 // Need set here because the data value on flash is different 241 // 242 Status = SetMorLockVariable (MOR_LOCK_DATA_LOCKED_WITH_KEY); 243 if (EFI_ERROR(Status)) { 244 // 245 // SetVar fail, do not provision the key 246 // 247 return Status; 248 } else { 249 // 250 // Lock success, provision the key 251 // 252 mMorLockKeyEmpty = FALSE; 253 CopyMem (mMorLockKey, Data, MOR_LOCK_V2_KEY_SIZE); 254 mMorLockState = MorLockStateLocked; 255 // 256 // return EFI_ALREADY_STARTED to skip variable set. 257 // 258 return EFI_ALREADY_STARTED; 259 } 260 } else { 261 ASSERT (FALSE); 262 return EFI_OUT_OF_RESOURCES; 263 } 264 } else { 265 // 266 // In Locked State 267 // 268 if (mMorLockKeyEmpty || (DataSize != MOR_LOCK_V2_KEY_SIZE)) { 269 return EFI_ACCESS_DENIED; 270 } 271 if ((CompareMem (Data, mMorLockKey, MOR_LOCK_V2_KEY_SIZE) == 0)) { 272 // 273 // Key match - unlock 274 // 275 276 // 277 // Need set here because the data value on flash is different 278 // 279 Status = SetMorLockVariable (MOR_LOCK_DATA_UNLOCKED); 280 if (EFI_ERROR (Status)) { 281 // 282 // SetVar fail 283 // 284 return Status; 285 } else { 286 // 287 // Unlock Success 288 // 289 mMorLockState = MorLockStateUnlocked; 290 mMorLockKeyEmpty = TRUE; 291 ZeroMem (mMorLockKey, sizeof(mMorLockKey)); 292 // 293 // return EFI_ALREADY_STARTED to skip variable set. 294 // 295 return EFI_ALREADY_STARTED; 296 } 297 } else { 298 // 299 // Key mismatch - Prevent Dictionary Attack 300 // 301 mMorLockState = MorLockStateLocked; 302 mMorLockKeyEmpty = TRUE; 303 ZeroMem (mMorLockKey, sizeof(mMorLockKey)); 304 return EFI_ACCESS_DENIED; 305 } 306 } 307 } 308 309 /** 310 This service is an MOR/MorLock checker handler for the SetVariable(). 311 312 @param VariableName the name of the vendor's variable, as a 313 Null-Terminated Unicode String 314 @param VendorGuid Unify identifier for vendor. 315 @param Attributes Point to memory location to return the attributes of variable. If the point 316 is NULL, the parameter would be ignored. 317 @param DataSize The size in bytes of Data-Buffer. 318 @param Data Point to the content of the variable. 319 320 @retval EFI_SUCCESS The MOR/MorLock check pass, and Variable driver can store the variable data. 321 @retval EFI_INVALID_PARAMETER The MOR/MorLock data or data size or attributes is not allowed for MOR variable. 322 @retval EFI_ACCESS_DENIED The MOR/MorLock is locked. 323 @retval EFI_ALREADY_STARTED The MorLock variable is handled inside this function. 324 Variable driver can just return EFI_SUCCESS. 325 **/ 326 EFI_STATUS 327 SetVariableCheckHandlerMor ( 328 IN CHAR16 *VariableName, 329 IN EFI_GUID *VendorGuid, 330 IN UINT32 Attributes, 331 IN UINTN DataSize, 332 IN VOID *Data 333 ) 334 { 335 // 336 // do not handle non-MOR variable 337 // 338 if (!IsAnyMorVariable (VariableName, VendorGuid)) { 339 return EFI_SUCCESS; 340 } 341 342 // 343 // MorLock variable 344 // 345 if (IsMorLockVariable (VariableName, VendorGuid)) { 346 return SetVariableCheckHandlerMorLock ( 347 VariableName, 348 VendorGuid, 349 Attributes, 350 DataSize, 351 Data 352 ); 353 } 354 355 // 356 // Mor Variable 357 // 358 359 // 360 // Basic Check 361 // 362 if ((Attributes != (EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS)) || 363 (DataSize != sizeof(UINT8)) || 364 (Data == NULL)) { 365 return EFI_INVALID_PARAMETER; 366 } 367 if (mMorLockState == MorLockStateLocked) { 368 // 369 // If lock, deny access 370 // 371 return EFI_ACCESS_DENIED; 372 } 373 // 374 // grant access 375 // 376 return EFI_SUCCESS; 377 } 378 379 /** 380 Initialization for MOR Lock Control. 381 382 @retval EFI_SUCEESS MorLock initialization success. 383 @return Others Some error occurs. 384 **/ 385 EFI_STATUS 386 MorLockInit ( 387 VOID 388 ) 389 { 390 // 391 // Set variable to report capability to OS 392 // 393 return SetMorLockVariable (0); 394 } 395
