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/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Functions for querying, manipulating and locking rollback indices
* stored in the TPM NVRAM.
*/
#include <security/vboot/antirollback.h>
#include <security/vboot/tpm_common.h>
#include <string.h>
#include <security/tpm/tspi.h>
#include <vb2_api.h>
#include <console/console.h>
#ifdef FOR_TEST
#include <stdio.h>
#define VBDEBUG(format, args...) printf(format, ## args)
#else
#define VBDEBUG(format, args...) \
printk(BIOS_INFO, "%s():%d: " format, __func__, __LINE__, ## args)
#endif
#define RETURN_ON_FAILURE(tpm_cmd) do { \
uint32_t result_; \
if ((result_ = (tpm_cmd)) != TPM_SUCCESS) { \
VBDEBUG("Antirollback: %08x returned by " #tpm_cmd \
"\n", (int)result_); \
return result_; \
} \
} while (0)
#define TPM_PCR_GBB_FLAGS_NAME "GBB flags"
#define TPM_PCR_GBB_HWID_NAME "GBB HWID"
static uint32_t safe_write(uint32_t index, const void *data, uint32_t length);
static uint32_t read_space_firmware(struct vb2_context *ctx)
{
int attempts = 3;
while (attempts--) {
RETURN_ON_FAILURE(tlcl_read(FIRMWARE_NV_INDEX,
ctx->secdata_firmware,
VB2_SECDATA_FIRMWARE_SIZE));
if (vb2api_secdata_firmware_check(ctx) == VB2_SUCCESS)
return TPM_SUCCESS;
VBDEBUG("TPM: %s() - bad CRC\n", __func__);
}
VBDEBUG("TPM: %s() - too many bad CRCs, giving up\n", __func__);
return TPM_E_CORRUPTED_STATE;
}
static uint32_t read_space_rec_hash(uint8_t *data)
{
RETURN_ON_FAILURE(tlcl_read(REC_HASH_NV_INDEX, data,
REC_HASH_NV_SIZE));
return TPM_SUCCESS;
}
static uint32_t write_secdata(uint32_t index,
const uint8_t *secdata,
uint32_t len)
{
uint8_t sd[32];
uint32_t rv;
int attempts = 3;
if (len > sizeof(sd)) {
VBDEBUG("TPM: %s() - data is too large\n", __func__);
return TPM_E_WRITE_FAILURE;
}
while (attempts--) {
rv = safe_write(index, secdata, len);
/* Can't write, not gonna try again */
if (rv != TPM_SUCCESS)
return rv;
/* Read it back to be sure it got the right values. */
rv = tlcl_read(index, sd, len);
if (rv == TPM_SUCCESS && memcmp(secdata, sd, len) == 0)
return rv;
VBDEBUG("TPM: %s() failed. trying again\n", __func__);
/* Try writing it again. Maybe it was garbled on the way out. */
}
VBDEBUG("TPM: %s() - too many failures, giving up\n", __func__);
return TPM_E_CORRUPTED_STATE;
}
/*
* This is used to initialize the TPM space for recovery hash after defining
* it. Since there is no data available to calculate hash at the point where TPM
* space is defined, initialize it to all 0s.
*/
static const uint8_t rec_hash_data[REC_HASH_NV_SIZE] = { };
#if CONFIG(TPM2)
/*
* Different sets of NVRAM space attributes apply to the "ro" spaces,
* i.e. those which should not be possible to delete or modify once
* the RO exits, and the rest of the NVRAM spaces.
*/
static const TPMA_NV ro_space_attributes = {
.TPMA_NV_PPWRITE = 1,
.TPMA_NV_AUTHREAD = 1,
.TPMA_NV_PPREAD = 1,
.TPMA_NV_PLATFORMCREATE = 1,
.TPMA_NV_WRITE_STCLEAR = 1,
.TPMA_NV_POLICY_DELETE = 1,
};
static const TPMA_NV rw_space_attributes = {
.TPMA_NV_PPWRITE = 1,
.TPMA_NV_AUTHREAD = 1,
.TPMA_NV_PPREAD = 1,
.TPMA_NV_PLATFORMCREATE = 1,
};
/*
* This policy digest was obtained using TPM2_PolicyPCR
* selecting only PCR_0 with a value of all zeros.
*/
static const uint8_t pcr0_unchanged_policy[] = {
0x09, 0x93, 0x3C, 0xCE, 0xEB, 0xB4, 0x41, 0x11, 0x18, 0x81, 0x1D,
0xD4, 0x47, 0x78, 0x80, 0x08, 0x88, 0x86, 0x62, 0x2D, 0xD7, 0x79,
0x94, 0x46, 0x62, 0x26, 0x68, 0x8E, 0xEE, 0xE6, 0x6A, 0xA1};
/* Nothing special in the TPM2 path yet. */
static uint32_t safe_write(uint32_t index, const void *data, uint32_t length)
{
return tlcl_write(index, data, length);
}
static uint32_t set_space(const char *name, uint32_t index, const void *data,
uint32_t length, const TPMA_NV nv_attributes,
const uint8_t *nv_policy, size_t nv_policy_size)
{
uint32_t rv;
rv = tlcl_define_space(index, length, nv_attributes, nv_policy,
nv_policy_size);
if (rv == TPM_E_NV_DEFINED) {
/*
* Continue with writing: it may be defined, but not written
* to. In that case a subsequent tlcl_read() would still return
* TPM_E_BADINDEX on TPM 2.0. The cases when some non-firmware
* space is defined while the firmware space is not there
* should be rare (interrupted initialization), so no big harm
* in writing once again even if it was written already.
*/
VBDEBUG("%s: %s space already exists\n", __func__, name);
rv = TPM_SUCCESS;
}
if (rv != TPM_SUCCESS)
return rv;
return write_secdata(index, data, length);
}
static uint32_t set_firmware_space(const void *firmware_blob)
{
return set_space("firmware", FIRMWARE_NV_INDEX, firmware_blob,
VB2_SECDATA_FIRMWARE_SIZE, ro_space_attributes,
pcr0_unchanged_policy, sizeof(pcr0_unchanged_policy));
}
static uint32_t set_kernel_space(const void *kernel_blob)
{
return set_space("kernel", KERNEL_NV_INDEX, kernel_blob,
VB2_SECDATA_KERNEL_SIZE, rw_space_attributes, NULL, 0);
}
static uint32_t set_rec_hash_space(const uint8_t *data)
{
return set_space("MRC Hash", REC_HASH_NV_INDEX, data,
REC_HASH_NV_SIZE,
ro_space_attributes, pcr0_unchanged_policy,
sizeof(pcr0_unchanged_policy));
}
static uint32_t _factory_initialize_tpm(struct vb2_context *ctx)
{
RETURN_ON_FAILURE(tlcl_force_clear());
/*
* Of all NVRAM spaces defined by this function the firmware space
* must be defined last, because its existence is considered an
* indication that TPM factory initialization was successfully
* completed.
*/
RETURN_ON_FAILURE(set_kernel_space(ctx->secdata_kernel));
if (CONFIG(VBOOT_HAS_REC_HASH_SPACE))
RETURN_ON_FAILURE(set_rec_hash_space(rec_hash_data));
RETURN_ON_FAILURE(set_firmware_space(ctx->secdata_firmware));
return TPM_SUCCESS;
}
uint32_t antirollback_lock_space_firmware(void)
{
return tlcl_lock_nv_write(FIRMWARE_NV_INDEX);
}
uint32_t antirollback_lock_space_rec_hash(void)
{
return tlcl_lock_nv_write(REC_HASH_NV_INDEX);
}
#else
/**
* Like tlcl_write(), but checks for write errors due to hitting the 64-write
* limit and clears the TPM when that happens. This can only happen when the
* TPM is unowned, so it is OK to clear it (and we really have no choice).
* This is not expected to happen frequently, but it could happen.
*/
static uint32_t safe_write(uint32_t index, const void *data, uint32_t length)
{
uint32_t result = tlcl_write(index, data, length);
if (result == TPM_E_MAXNVWRITES) {
RETURN_ON_FAILURE(tpm_clear_and_reenable());
return tlcl_write(index, data, length);
} else {
return result;
}
}
/**
* Similarly to safe_write(), this ensures we don't fail a DefineSpace because
* we hit the TPM write limit. This is even less likely to happen than with
* writes because we only define spaces once at initialization, but we'd
* rather be paranoid about this.
*/
static uint32_t safe_define_space(uint32_t index, uint32_t perm, uint32_t size)
{
uint32_t result = tlcl_define_space(index, perm, size);
if (result == TPM_E_MAXNVWRITES) {
RETURN_ON_FAILURE(tpm_clear_and_reenable());
return tlcl_define_space(index, perm, size);
} else {
return result;
}
}
static uint32_t set_rec_hash_space(const uint8_t *data)
{
RETURN_ON_FAILURE(safe_define_space(REC_HASH_NV_INDEX,
TPM_NV_PER_GLOBALLOCK |
TPM_NV_PER_PPWRITE,
REC_HASH_NV_SIZE));
RETURN_ON_FAILURE(write_secdata(REC_HASH_NV_INDEX, data,
REC_HASH_NV_SIZE));
return TPM_SUCCESS;
}
static uint32_t _factory_initialize_tpm(struct vb2_context *ctx)
{
TPM_PERMANENT_FLAGS pflags;
uint32_t result;
result = tlcl_get_permanent_flags(&pflags);
if (result != TPM_SUCCESS)
return result;
/*
* TPM may come from the factory without physical presence finalized.
* Fix if necessary.
*/
VBDEBUG("TPM: physicalPresenceLifetimeLock=%d\n",
pflags.physicalPresenceLifetimeLock);
if (!pflags.physicalPresenceLifetimeLock) {
VBDEBUG("TPM: Finalizing physical presence\n");
RETURN_ON_FAILURE(tlcl_finalize_physical_presence());
}
/*
* The TPM will not enforce the NV authorization restrictions until the
* execution of a TPM_NV_DefineSpace with the handle of
* TPM_NV_INDEX_LOCK. Here we create that space if it doesn't already
* exist. */
VBDEBUG("TPM: nvLocked=%d\n", pflags.nvLocked);
if (!pflags.nvLocked) {
VBDEBUG("TPM: Enabling NV locking\n");
RETURN_ON_FAILURE(tlcl_set_nv_locked());
}
/* Clear TPM owner, in case the TPM is already owned for some reason. */
VBDEBUG("TPM: Clearing owner\n");
RETURN_ON_FAILURE(tpm_clear_and_reenable());
/* Define and write secdata_kernel space. */
RETURN_ON_FAILURE(safe_define_space(KERNEL_NV_INDEX,
TPM_NV_PER_PPWRITE,
VB2_SECDATA_KERNEL_SIZE));
RETURN_ON_FAILURE(write_secdata(KERNEL_NV_INDEX,
ctx->secdata_kernel,
VB2_SECDATA_KERNEL_SIZE));
/* Define and write secdata_firmware space. */
RETURN_ON_FAILURE(safe_define_space(FIRMWARE_NV_INDEX,
TPM_NV_PER_GLOBALLOCK |
TPM_NV_PER_PPWRITE,
VB2_SECDATA_FIRMWARE_SIZE));
RETURN_ON_FAILURE(write_secdata(FIRMWARE_NV_INDEX,
ctx->secdata_firmware,
VB2_SECDATA_FIRMWARE_SIZE));
/* Define and set rec hash space, if available. */
if (CONFIG(VBOOT_HAS_REC_HASH_SPACE))
RETURN_ON_FAILURE(set_rec_hash_space(rec_hash_data));
return TPM_SUCCESS;
}
uint32_t antirollback_lock_space_firmware(void)
{
return tlcl_set_global_lock();
}
uint32_t antirollback_lock_space_rec_hash(void)
{
/*
* Nothing needs to be done here, since global lock is already set while
* locking firmware space.
*/
return TPM_SUCCESS;
}
#endif
/**
* Perform one-time initializations.
*
* Create the NVRAM spaces, and set their initial values as needed. Sets the
* nvLocked bit and ensures the physical presence command is enabled and
* locked.
*/
static uint32_t factory_initialize_tpm(struct vb2_context *ctx)
{
uint32_t result;
/* Set initial values of secdata_firmware and secdata_kernel spaces. */
vb2api_secdata_firmware_create(ctx);
vb2api_secdata_kernel_create(ctx);
VBDEBUG("TPM: factory initialization\n");
/*
* Do a full test. This only happens the first time the device is
* turned on in the factory, so performance is not an issue. This is
* almost certainly not necessary, but it gives us more confidence
* about some code paths below that are difficult to
* test---specifically the ones that set lifetime flags, and are only
* executed once per physical TPM.
*/
result = tlcl_self_test_full();
if (result != TPM_SUCCESS)
return result;
result = _factory_initialize_tpm(ctx);
if (result != TPM_SUCCESS)
return result;
/* _factory_initialize_tpm() writes initial secdata values to TPM
immediately, so let vboot know that it's up to date now. */
ctx->flags &= ~(VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED |
VB2_CONTEXT_SECDATA_KERNEL_CHANGED);
VBDEBUG("TPM: factory initialization successful\n");
return TPM_SUCCESS;
}
uint32_t antirollback_read_space_firmware(struct vb2_context *ctx)
{
uint32_t rv;
/* Read the firmware space. */
rv = read_space_firmware(ctx);
if (rv == TPM_E_BADINDEX) {
/* This seems the first time we've run. Initialize the TPM. */
VBDEBUG("TPM: Not initialized yet.\n");
RETURN_ON_FAILURE(factory_initialize_tpm(ctx));
} else if (rv != TPM_SUCCESS) {
VBDEBUG("TPM: Firmware space in a bad state; giving up.\n");
return TPM_E_CORRUPTED_STATE;
}
return TPM_SUCCESS;
}
uint32_t antirollback_write_space_firmware(struct vb2_context *ctx)
{
if (CONFIG(CR50_IMMEDIATELY_COMMIT_FW_SECDATA))
tlcl_cr50_enable_nvcommits();
return write_secdata(FIRMWARE_NV_INDEX, ctx->secdata_firmware,
VB2_SECDATA_FIRMWARE_SIZE);
}
uint32_t antirollback_read_space_rec_hash(uint8_t *data, uint32_t size)
{
if (size != REC_HASH_NV_SIZE) {
VBDEBUG("TPM: Incorrect buffer size for rec hash. "
"(Expected=0x%x Actual=0x%x).\n", REC_HASH_NV_SIZE,
size);
return TPM_E_READ_FAILURE;
}
return read_space_rec_hash(data);
}
uint32_t antirollback_write_space_rec_hash(const uint8_t *data, uint32_t size)
{
uint8_t spc_data[REC_HASH_NV_SIZE];
uint32_t rv;
if (size != REC_HASH_NV_SIZE) {
VBDEBUG("TPM: Incorrect buffer size for rec hash. "
"(Expected=0x%x Actual=0x%x).\n", REC_HASH_NV_SIZE,
size);
return TPM_E_WRITE_FAILURE;
}
rv = read_space_rec_hash(spc_data);
if (rv == TPM_E_BADINDEX) {
/*
* If space is not defined already for recovery hash, define
* new space.
*/
VBDEBUG("TPM: Initializing recovery hash space.\n");
return set_rec_hash_space(data);
}
if (rv != TPM_SUCCESS)
return rv;
return write_secdata(REC_HASH_NV_INDEX, data, size);
}
vb2_error_t vb2ex_tpm_clear_owner(struct vb2_context *ctx)
{
uint32_t rv;
printk(BIOS_INFO, "Clearing TPM owner\n");
rv = tpm_clear_and_reenable();
if (rv)
return VB2_ERROR_EX_TPM_CLEAR_OWNER;
return VB2_SUCCESS;
}