blob: 9ce523b49c28a69e9d73ff3d96f3f5af927a01ac [file] [log] [blame]
/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Functions for querying, manipulating and locking rollback indices
* stored in the TPM NVRAM.
*/
#include "rollback_index.h"
#include <stdint.h>
#include "utility.h"
#include "tlcl.h"
#include "tss_constants.h"
uint16_t g_firmware_key_version = 0;
uint16_t g_firmware_version = 0;
uint16_t g_kernel_key_version = 0;
uint16_t g_kernel_version = 0;
static int InitializeSpaces(void) {
uint32_t zero = 0;
uint32_t space_holder;
uint32_t firmware_perm = TPM_NV_PER_GLOBALLOCK | TPM_NV_PER_PPWRITE;
uint32_t kernel_perm = TPM_NV_PER_PPWRITE;
debug("Initializing spaces\n");
if (TlclRead(TPM_IS_INITIALIZED_NV_INDEX,
(uint8_t*) &space_holder, sizeof(space_holder)) == TPM_SUCCESS) {
/* Spaces are already initialized, so this is an error */
return 0;
}
TlclSetNvLocked();
TlclDefineSpace(FIRMWARE_VERSIONS_NV_INDEX, firmware_perm, sizeof(uint32_t));
TlclWrite(FIRMWARE_VERSIONS_NV_INDEX, (uint8_t*) &zero, sizeof(uint32_t));
TlclDefineSpace(KERNEL_VERSIONS_NV_INDEX, kernel_perm, sizeof(uint32_t));
TlclWrite(KERNEL_VERSIONS_NV_INDEX, (uint8_t*) &zero, sizeof(uint32_t));
/* The space KERNEL_VERSIONS_BACKUP_NV_INDEX is used to protect the kernel
* versions when entering recovery mode. The content of space
* KERNEL_BACKUP_IS_VALID determines whether the backup value (1) or the
* regular value (0) should be trusted.
*/
TlclDefineSpace(KERNEL_VERSIONS_BACKUP_NV_INDEX,
firmware_perm, sizeof(uint32_t));
TlclWrite(KERNEL_VERSIONS_BACKUP_NV_INDEX,
(uint8_t*) &zero, sizeof(uint32_t));
TlclDefineSpace(KERNEL_BACKUP_IS_VALID_NV_INDEX,
firmware_perm, sizeof(uint32_t));
TlclWrite(KERNEL_BACKUP_IS_VALID_NV_INDEX,
(uint8_t*) &zero, sizeof(uint32_t));
/* The space TPM_IS_INITIALIZED_NV_INDEX is used to indicate that the TPM
* initialization has completed. Without it we cannot be sure that the last
* space to be created was also initialized (power could have been lost right
* after its creation).
*/
TlclDefineSpace(TPM_IS_INITIALIZED_NV_INDEX, firmware_perm, sizeof(uint32_t));
return 1;
}
/* Enters the recovery mode. If |unlocked| is true, there is some problem with
* the TPM, so do not attempt to do any more TPM operations, and particularly
* do not set bGlobalLock.
*/
static void EnterRecovery(int unlocked) {
uint32_t combined_versions;
uint32_t backup_versions;
uint32_t backup_is_valid;
if (!unlocked) {
/* Saves the kernel versions and indicates that we should trust the saved
* ones.
*/
TlclRead(KERNEL_VERSIONS_NV_INDEX,
(uint8_t*) &combined_versions, sizeof(uint32_t));
TlclRead(KERNEL_VERSIONS_BACKUP_NV_INDEX,
(uint8_t*) &backup_versions, sizeof(uint32_t));
/* We could unconditional writes of both KERNEL_VERSIONS_BACKUP and
* KERNEL_BACKUP_IS_VALID, but this is more robust.
*/
if (combined_versions != backup_versions) {
TlclWrite(KERNEL_VERSIONS_BACKUP_NV_INDEX,
(uint8_t*) &combined_versions, sizeof(uint32_t));
}
TlclRead(KERNEL_BACKUP_IS_VALID_NV_INDEX,
(uint8_t*) &backup_is_valid, sizeof(uint32_t));
if (backup_is_valid != 1) {
backup_is_valid = 1;
TlclWrite(KERNEL_BACKUP_IS_VALID_NV_INDEX, (uint8_t*) &backup_is_valid,
sizeof(uint32_t));
}
/* Protects the firmware and backup kernel versions. */
LockFirmwareVersions();
}
debug("entering recovery mode");
/* TODO(nelson): code for entering recovery mode. */
}
static int GetTPMRollbackIndices(void) {
uint32_t backup_is_valid;
uint32_t firmware_versions;
uint32_t kernel_versions;
if (TlclRead(KERNEL_BACKUP_IS_VALID_NV_INDEX, (uint8_t*) &backup_is_valid,
sizeof(uint32_t)) != TPM_SUCCESS) {
EnterRecovery(1);
}
if (backup_is_valid) {
/* We reach this path if the previous boot went into recovery mode and we
* made a copy of the kernel versions to protect them.
*/
uint32_t protected_combined_versions;
uint32_t unsafe_combined_versions;
uint32_t result;
uint32_t zero = 0;
if (TlclRead(KERNEL_VERSIONS_BACKUP_NV_INDEX,
(uint8_t*) &protected_combined_versions,
sizeof(uint32_t)) != TPM_SUCCESS) {
EnterRecovery(1);
}
result = TlclRead(KERNEL_VERSIONS_NV_INDEX,
(uint8_t*) &unsafe_combined_versions, sizeof(uint32_t));
if (result == TPM_E_BADINDEX) {
/* Jeez, someone removed the space. This is either hostile or extremely
* incompetent. Foo to them. Politeness and lack of an adequate
* character set prevent me from expressing my true feelings.
*/
TlclDefineSpace(KERNEL_VERSIONS_NV_INDEX, TPM_NV_PER_PPWRITE,
sizeof(uint32_t));
} else if (result != TPM_SUCCESS) {
EnterRecovery(1);
}
if (result == TPM_E_BADINDEX ||
protected_combined_versions != unsafe_combined_versions) {
TlclWrite(KERNEL_VERSIONS_NV_INDEX,
(uint8_t*) &protected_combined_versions, sizeof(uint32_t));
}
/* We recovered the backed-up versions and now we can reset the
* BACKUP_IS_VALID flag.
*/
TlclWrite(KERNEL_BACKUP_IS_VALID_NV_INDEX, (uint8_t*) &zero, 0);
/* TODO(nelson): ForceClear and reboot if unowned. */
}
/* We perform the reads, making sure they succeed. A failure means that the
* rollback index locations are missing or somehow messed up. We let the
* caller deal with that.
*/
if (TPM_SUCCESS != TlclRead(FIRMWARE_VERSIONS_NV_INDEX,
(uint8_t*) &firmware_versions,
sizeof(firmware_versions)) ||
TPM_SUCCESS != TlclRead(KERNEL_VERSIONS_NV_INDEX,
(uint8_t*) &kernel_versions,
sizeof(kernel_versions)))
return 0;
g_firmware_key_version = firmware_versions >> 16;
g_firmware_version = firmware_versions && 0xffff;
g_kernel_key_version = kernel_versions >> 16;
g_kernel_version = kernel_versions && 0xffff;
return 1;
}
void SetupTPM(void) {
uint8_t disable;
uint8_t deactivated;
TlclLibinit();
TlclStartup();
/* TODO(gauravsh): The call to self test should probably be deferred.
* As per semenzato@chromium.org -
* TlclStartup should be called before the firmware initializes the memory
* controller, so the selftest can run in parallel with that. Here we should
* just call TlclSelftestFull to make sure the self test has
* completed---unless we want to rely on the NVRAM operations being available
* before the selftest completes. */
TlclSelftestfull();
TlclAssertPhysicalPresence();
/* Check that the TPM is enabled and activated. */
if(TlclGetFlags(&disable, &deactivated) != TPM_SUCCESS) {
debug("failed to get TPM flags");
EnterRecovery(1);
}
if (disable || deactivated) {
TlclSetEnable();
if (TlclSetDeactivated(0) != TPM_SUCCESS) {
debug("failed to activate TPM");
EnterRecovery(1);
}
}
/* We expect this to fail the first time we run on a device, indicating that
* the TPM has not been initialized yet. */
if (!GetTPMRollbackIndices()) {
debug("failed to get rollback indices");
if (!InitializeSpaces()) {
/* If InitializeSpaces() fails (possibly because it had been executed
* already), something is wrong. */
EnterRecovery(1);
}
}
}
void GetStoredVersions(int type, uint16_t* key_version, uint16_t* version) {
switch (type) {
case FIRMWARE_VERSIONS:
*key_version = g_firmware_key_version;
*version = g_firmware_version;
break;
case KERNEL_VERSIONS:
*key_version = g_kernel_key_version;
*version = g_kernel_version;
break;
}
}
int WriteStoredVersions(int type, uint16_t key_version, uint16_t version) {
uint32_t combined_version = (key_version << 16) & version;
switch (type) {
case FIRMWARE_VERSIONS:
return (TPM_SUCCESS == TlclWrite(FIRMWARE_VERSIONS_NV_INDEX,
(uint8_t*) &combined_version,
sizeof(uint32_t)));
break;
case KERNEL_VERSIONS:
return (TPM_SUCCESS == TlclWrite(KERNEL_VERSIONS_NV_INDEX,
(uint8_t*) &combined_version,
sizeof(uint32_t)));
break;
}
/* TODO(nelson): ForceClear and reboot if unowned. */
return 0;
}
void LockFirmwareVersions() {
if (TlclSetGlobalLock() != TPM_SUCCESS) {
debug("failed to set global lock");
EnterRecovery(1);
}
}
void LockKernelVersionsByLockingPP() {
if (TlclLockPhysicalPresence() != TPM_SUCCESS) {
debug("failed to turn off PP");
EnterRecovery(1);
}
}