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/* Copyright 2016 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.
*/
#include "2sysincludes.h"
#include "2hmac.h"
#include "2sha.h"
#include "bdb_api.h"
#include "bdb_struct.h"
#include "bdb.h"
#include "nvm.h"
#include "secrets.h"
static int nvmrw_validate(const void *buf, uint32_t size)
{
const struct nvmrw *nvm = buf;
if (nvm->struct_magic != NVM_RW_MAGIC)
return BDB_ERROR_NVM_RW_MAGIC;
if (nvm->struct_major_version != NVM_HEADER_VERSION_MAJOR)
return BDB_ERROR_NVM_STRUCT_VERSION;
if (size < nvm->struct_size)
return BDB_ERROR_NVM_STRUCT_SIZE;
/*
* We allow any sizes between min and max so that we can handle minor
* version mismatches. Reader can be older than data or the other way
* around. FW in slot B can upgrade NVM-RW but fails to qualify as a
* stable boot path. Then, FW in slot A is invoked which is older than
* the NVM-RW written by FW in slot B.
*/
if (nvm->struct_size < NVM_RW_MIN_STRUCT_SIZE ||
NVM_RW_MAX_STRUCT_SIZE < nvm->struct_size)
return BDB_ERROR_NVM_STRUCT_SIZE;
return BDB_SUCCESS;
}
static int nvmrw_verify(const struct bdb_ro_secrets *secrets,
const struct nvmrw *nvm, uint32_t size)
{
uint8_t mac[NVM_HMAC_SIZE];
int rv;
if (!secrets || !nvm)
return BDB_ERROR_NVM_INVALID_PARAMETER;
rv = nvmrw_validate(nvm, size);
if (rv)
return rv;
/* Compute and verify HMAC */
if (hmac(VB2_HASH_SHA256, secrets->nvm_rw, BDB_SECRET_SIZE,
nvm, nvm->struct_size - sizeof(mac), mac, sizeof(mac)))
return BDB_ERROR_NVM_RW_HMAC;
/* TODO: Use safe_memcmp */
if (memcmp(mac, nvm->hmac, sizeof(mac)))
return BDB_ERROR_NVM_RW_INVALID_HMAC;
return BDB_SUCCESS;
}
int nvmrw_write(struct vba_context *ctx, enum nvm_type type)
{
struct nvmrw *nvm = &ctx->nvmrw;
int retry = NVM_MAX_WRITE_RETRY;
int rv;
if (!ctx)
return BDB_ERROR_NVM_INVALID_PARAMETER;
if (!ctx->ro_secrets)
return BDB_ERROR_NVM_INVALID_SECRET;
rv = nvmrw_validate(nvm, sizeof(*nvm));
if (rv)
return rv;
/* Update HMAC */
hmac(VB2_HASH_SHA256, ctx->ro_secrets->nvm_rw, BDB_SECRET_SIZE,
nvm, nvm->struct_size - sizeof(nvm->hmac),
nvm->hmac, sizeof(nvm->hmac));
while (retry--) {
uint8_t buf[sizeof(struct nvmrw)];
if (vbe_write_nvm(type, nvm, nvm->struct_size))
continue;
if (vbe_read_nvm(type, buf, sizeof(buf)))
continue;
if (memcmp(buf, nvm, sizeof(buf)))
continue;
/* Write success */
return BDB_SUCCESS;
}
/* NVM seems corrupted. Go to chip recovery mode */
return BDB_ERROR_NVM_WRITE;
}
static int read_verify_nvmrw(enum nvm_type type,
const struct bdb_ro_secrets *secrets,
uint8_t *buf, uint32_t buf_size)
{
struct nvmrw *nvm = (struct nvmrw *)buf;
int rv;
/* Read minimum amount */
if (vbe_read_nvm(type, buf, NVM_MIN_STRUCT_SIZE))
return BDB_ERROR_NVM_VBE_READ;
/* Validate the content */
rv = nvmrw_validate(buf, buf_size);
if (rv)
return rv;
/* Read full body */
if (vbe_read_nvm(type, buf, nvm->struct_size))
return BDB_ERROR_NVM_VBE_READ;
/* Verify the content */
rv = nvmrw_verify(secrets, nvm, sizeof(*nvm));
return rv;
return BDB_SUCCESS;
}
int nvmrw_read(struct vba_context *ctx)
{
uint8_t buf1[NVM_RW_MAX_STRUCT_SIZE];
uint8_t buf2[NVM_RW_MAX_STRUCT_SIZE];
struct nvmrw *nvm1 = (struct nvmrw *)buf1;
struct nvmrw *nvm2 = (struct nvmrw *)buf2;
int rv1, rv2;
/* Read and verify the 1st copy */
rv1 = read_verify_nvmrw(NVM_TYPE_RW_PRIMARY, ctx->ro_secrets,
buf1, sizeof(buf1));
/* Read and verify the 2nd copy */
rv2 = read_verify_nvmrw(NVM_TYPE_RW_SECONDARY, ctx->ro_secrets,
buf2, sizeof(buf2));
if (rv1 == BDB_SUCCESS && rv2 == BDB_SUCCESS) {
/* Sync primary and secondary based on update_count. */
if (nvm1->update_count > nvm2->update_count)
rv2 = !BDB_SUCCESS;
else if (nvm1->update_count < nvm2->update_count)
rv1 = !BDB_SUCCESS;
} else if (rv1 != BDB_SUCCESS && rv2 != BDB_SUCCESS){
/* Abort. Neither was successful. */
return rv1;
}
if (rv1 == BDB_SUCCESS)
/* both copies are good. use primary copy */
memcpy(&ctx->nvmrw, buf1, sizeof(ctx->nvmrw));
else
/* primary is bad but secondary is good. */
memcpy(&ctx->nvmrw, buf2, sizeof(ctx->nvmrw));
if (ctx->nvmrw.struct_minor_version != NVM_HEADER_VERSION_MINOR) {
/*
* Upgrade or downgrade is required. So, we need to write both.
* When upgrading, this is the place where new fields should be
* initialized. We don't increment update_count.
*/
ctx->nvmrw.struct_minor_version = NVM_HEADER_VERSION_MINOR;
ctx->nvmrw.struct_size = sizeof(ctx->nvmrw);
/* We don't worry about calculating hmac twice because
* this is a corner case. */
rv1 = nvmrw_write(ctx, NVM_TYPE_RW_PRIMARY);
rv2 = nvmrw_write(ctx, NVM_TYPE_RW_SECONDARY);
} else if (rv1 != BDB_SUCCESS) {
/* primary copy is bad. sync it with secondary copy */
rv1 = nvmrw_write(ctx, NVM_TYPE_RW_PRIMARY);
} else if (rv2 != BDB_SUCCESS){
/* secondary copy is bad. sync it with primary copy */
rv2 = nvmrw_write(ctx, NVM_TYPE_RW_SECONDARY);
} else {
/* Both copies are good and versions are same as the reader.
* Skip writing. This should be the common case. */
}
if (rv1 || rv2)
return rv1 ? rv1 : rv2;
return BDB_SUCCESS;
}
static int nvmrw_init(struct vba_context *ctx)
{
if (nvmrw_read(ctx))
return BDB_ERROR_NVM_INIT;
return BDB_SUCCESS;
}
int vba_update_kernel_version(struct vba_context *ctx,
uint32_t kernel_data_key_version,
uint32_t kernel_version)
{
struct nvmrw *nvm = &ctx->nvmrw;
if (nvmrw_verify(ctx->ro_secrets, nvm, sizeof(*nvm))) {
if (nvmrw_init(ctx))
return BDB_ERROR_NVM_INIT;
}
if (nvm->min_kernel_data_key_version < kernel_data_key_version ||
nvm->min_kernel_version < kernel_version) {
int rv1, rv2;
/* Roll forward versions */
nvm->min_kernel_data_key_version = kernel_data_key_version;
nvm->min_kernel_version = kernel_version;
/* Increment update counter */
nvm->update_count++;
/* Update both copies */
rv1 = nvmrw_write(ctx, NVM_TYPE_RW_PRIMARY);
rv2 = nvmrw_write(ctx, NVM_TYPE_RW_SECONDARY);
if (rv1 || rv2)
return BDB_ERROR_RECOVERY_REQUEST;
}
return BDB_SUCCESS;
}
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