fwupd/plugins/tpm/fu-plugin-tpm.c
Richard Hughes 510a9bfe0c Merge tpm-eventlog into the tpm plugin
This is so much less complicated.
2021-11-02 13:47:25 +00:00

305 lines
9.0 KiB
C

/*
* Copyright (C) 2019 Richard Hughes <richard@hughsie.com>
*
* SPDX-License-Identifier: LGPL-2.1+
*/
#include "config.h"
#include <fwupdplugin.h>
#include "fu-tpm-eventlog-parser.h"
#include "fu-tpm-v1-device.h"
#include "fu-tpm-v2-device.h"
struct FuPluginData {
FuTpmDevice *tpm_device;
FuDevice *bios_device;
GPtrArray *ev_items; /* of FuTpmEventlogItem */
};
void
fu_plugin_init(FuPlugin *plugin)
{
fu_plugin_alloc_data(plugin, sizeof(FuPluginData));
fu_plugin_set_build_hash(plugin, FU_BUILD_HASH);
fu_plugin_add_rule(plugin, FU_PLUGIN_RULE_CONFLICTS, "tpm_eventlog"); /* old name */
fu_plugin_add_udev_subsystem(plugin, "tpm");
fu_plugin_add_device_gtype(plugin, FU_TYPE_TPM_V2_DEVICE);
}
void
fu_plugin_destroy(FuPlugin *plugin)
{
FuPluginData *data = fu_plugin_get_data(plugin);
if (data->tpm_device != NULL)
g_object_unref(data->tpm_device);
if (data->bios_device != NULL)
g_object_unref(data->bios_device);
if (data->ev_items != NULL)
g_ptr_array_unref(data->ev_items);
}
static void
fu_plugin_tpm_set_bios_pcr0s(FuPlugin *plugin)
{
FuPluginData *data = fu_plugin_get_data(plugin);
g_autoptr(GError) error_local = NULL;
g_autoptr(GPtrArray) pcr0s = NULL;
if (data->tpm_device == NULL)
return;
if (data->bios_device == NULL)
return;
/* add all the PCR0s */
pcr0s = fu_tpm_device_get_checksums(data->tpm_device, 0);
if (pcr0s->len == 0)
return;
for (guint i = 0; i < pcr0s->len; i++) {
const gchar *checksum = g_ptr_array_index(pcr0s, i);
fu_device_add_checksum(data->bios_device, checksum);
}
fu_device_add_flag(data->bios_device, FWUPD_DEVICE_FLAG_CAN_VERIFY);
}
/* set the PCR0 as the device checksum */
void
fu_plugin_device_registered(FuPlugin *plugin, FuDevice *device)
{
FuPluginData *data = fu_plugin_get_data(plugin);
if (fu_device_has_instance_id(device, "main-system-firmware")) {
g_set_object(&data->bios_device, device);
fu_plugin_tpm_set_bios_pcr0s(plugin);
}
}
void
fu_plugin_device_added(FuPlugin *plugin, FuDevice *dev)
{
FuPluginData *data = fu_plugin_get_data(plugin);
g_autoptr(GPtrArray) pcr0s = NULL;
g_set_object(&data->tpm_device, FU_TPM_DEVICE(dev));
fu_plugin_add_report_metadata(plugin,
"TpmFamily",
fu_tpm_device_get_family(FU_TPM_DEVICE(dev)));
/* ensure */
fu_plugin_tpm_set_bios_pcr0s(plugin);
/* add extra plugin metadata */
pcr0s = fu_tpm_device_get_checksums(data->tpm_device, 0);
for (guint i = 0; i < pcr0s->len; i++) {
const gchar *csum = g_ptr_array_index(pcr0s, i);
GChecksumType csum_type = fwupd_checksum_guess_kind(csum);
if (csum_type == G_CHECKSUM_SHA1) {
fu_plugin_add_report_metadata(plugin, "Pcr0_SHA1", csum);
continue;
}
if (csum_type == G_CHECKSUM_SHA256) {
fu_plugin_add_report_metadata(plugin, "Pcr0_SHA256", csum);
continue;
}
}
}
static void
fu_plugin_tpm_add_security_attr_version(FuPlugin *plugin, FuSecurityAttrs *attrs)
{
FuPluginData *data = fu_plugin_get_data(plugin);
g_autoptr(FwupdSecurityAttr) attr = NULL;
/* create attr */
attr = fwupd_security_attr_new(FWUPD_SECURITY_ATTR_ID_TPM_VERSION_20);
fwupd_security_attr_set_plugin(attr, fu_plugin_get_name(plugin));
fwupd_security_attr_set_level(attr, FWUPD_SECURITY_ATTR_LEVEL_CRITICAL);
fu_security_attrs_append(attrs, attr);
/* check exists, and in v2.0 mode */
if (data->tpm_device == NULL) {
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_NOT_FOUND);
return;
}
if (g_strcmp0(fu_tpm_device_get_family(data->tpm_device), "2.0") != 0) {
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_NOT_ENABLED);
return;
}
/* success */
fwupd_security_attr_add_guids(attr, fu_device_get_guids(FU_DEVICE(data->tpm_device)));
fwupd_security_attr_add_flag(attr, FWUPD_SECURITY_ATTR_FLAG_SUCCESS);
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_FOUND);
}
static void
fu_plugin_tpm_add_security_attr_eventlog(FuPlugin *plugin, FuSecurityAttrs *attrs)
{
FuPluginData *data = fu_plugin_get_data(plugin);
gboolean reconstructed;
g_autoptr(FwupdSecurityAttr) attr = NULL;
g_autoptr(GError) error = NULL;
g_autoptr(GPtrArray) pcr0s_calc = NULL;
g_autoptr(GPtrArray) pcr0s_real = NULL;
/* no TPM device */
if (data->tpm_device == NULL)
return;
/* create attr */
attr = fwupd_security_attr_new(FWUPD_SECURITY_ATTR_ID_TPM_RECONSTRUCTION_PCR0);
fwupd_security_attr_set_plugin(attr, fu_plugin_get_name(plugin));
fwupd_security_attr_set_level(attr, FWUPD_SECURITY_ATTR_LEVEL_IMPORTANT);
fwupd_security_attr_add_guids(attr, fu_device_get_guids(data->tpm_device));
fu_security_attrs_append(attrs, attr);
/* check reconstructed to PCR0 */
if (fu_plugin_has_flag(plugin, FWUPD_PLUGIN_FLAG_DISABLED) || data->bios_device == NULL ||
data->ev_items == NULL) {
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_NOT_FOUND);
return;
}
/* calculate from the eventlog */
pcr0s_calc = fu_tpm_eventlog_calc_checksums(data->ev_items, 0, &error);
if (pcr0s_calc == NULL) {
g_warning("failed to get eventlog reconstruction: %s", error->message);
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_NOT_VALID);
return;
}
/* compare against the real PCR0s */
pcr0s_real = fu_tpm_device_get_checksums(data->tpm_device, 0);
for (guint i = 0; i < pcr0s_real->len; i++) {
const gchar *checksum = g_ptr_array_index(pcr0s_real, i);
reconstructed = FALSE;
for (guint j = 0; j < pcr0s_calc->len; j++) {
const gchar *checksum_tmp = g_ptr_array_index(pcr0s_calc, j);
/* skip unless same algorithm */
if (strlen(checksum) != strlen(checksum_tmp))
continue;
g_debug("comparing TPM %s and EVT %s", checksum, checksum_tmp);
if (g_strcmp0(checksum, checksum_tmp) == 0) {
reconstructed = TRUE;
break;
}
}
/* all algorithms must match */
if (!reconstructed)
break;
}
if (!reconstructed) {
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_NOT_VALID);
return;
}
/* success */
fwupd_security_attr_add_flag(attr, FWUPD_SECURITY_ATTR_FLAG_SUCCESS);
fwupd_security_attr_set_result(attr, FWUPD_SECURITY_ATTR_RESULT_VALID);
}
void
fu_plugin_add_security_attrs(FuPlugin *plugin, FuSecurityAttrs *attrs)
{
fu_plugin_tpm_add_security_attr_version(plugin, attrs);
fu_plugin_tpm_add_security_attr_eventlog(plugin, attrs);
}
static gchar *
fu_plugin_tpm_eventlog_report_metadata(FuPlugin *plugin)
{
FuPluginData *data = fu_plugin_get_data(plugin);
GString *str = g_string_new("");
g_autoptr(GPtrArray) pcrs = NULL;
for (guint i = 0; i < data->ev_items->len; i++) {
FuTpmEventlogItem *item = g_ptr_array_index(data->ev_items, i);
g_autofree gchar *blobstr = fu_tpm_eventlog_blobstr(item->blob);
g_autofree gchar *checksum = NULL;
if (item->checksum_sha1 != NULL)
checksum = fu_tpm_eventlog_strhex(item->checksum_sha1);
else if (item->checksum_sha256 != NULL)
checksum = fu_tpm_eventlog_strhex(item->checksum_sha256);
else
continue;
g_string_append_printf(str, "0x%08x %s", item->kind, checksum);
if (blobstr != NULL)
g_string_append_printf(str, " [%s]", blobstr);
g_string_append(str, "\n");
}
pcrs = fu_tpm_eventlog_calc_checksums(data->ev_items, 0, NULL);
if (pcrs != NULL) {
for (guint j = 0; j < pcrs->len; j++) {
const gchar *csum = g_ptr_array_index(pcrs, j);
g_string_append_printf(str, "PCR0: %s\n", csum);
}
}
if (str->len > 0)
g_string_truncate(str, str->len - 1);
return g_string_free(str, FALSE);
}
static gboolean
fu_plugin_tpm_coldplug_eventlog(FuPlugin *plugin, GError **error)
{
FuPluginData *data = fu_plugin_get_data(plugin);
gsize bufsz = 0;
const gchar *fn = "/sys/kernel/security/tpm0/binary_bios_measurements";
g_autofree gchar *str = NULL;
g_autofree guint8 *buf = NULL;
if (!g_file_get_contents(fn, (gchar **)&buf, &bufsz, error))
return FALSE;
if (bufsz == 0) {
g_set_error(error,
FWUPD_ERROR,
FWUPD_ERROR_INVALID_FILE,
"failed to read data from %s",
fn);
return FALSE;
}
data->ev_items =
fu_tpm_eventlog_parser_new(buf, bufsz, FU_TPM_EVENTLOG_PARSER_FLAG_NONE, error);
if (data->ev_items == NULL)
return FALSE;
/* add optional report metadata */
str = fu_plugin_tpm_eventlog_report_metadata(plugin);
fu_plugin_add_report_metadata(plugin, "TpmEventLog", str);
return TRUE;
}
gboolean
fu_plugin_coldplug(FuPlugin *plugin, GError **error)
{
g_autoptr(GError) error_local = NULL;
/* best effort */
if (!fu_plugin_tpm_coldplug_eventlog(plugin, &error_local))
g_warning("failed to load eventlog: %s", error_local->message);
/* success */
return TRUE;
}
gboolean
fu_plugin_startup(FuPlugin *plugin, GError **error)
{
FuPluginData *data = fu_plugin_get_data(plugin);
g_autofree gchar *sysfstpmdir = NULL;
g_autofree gchar *fn_pcrs = NULL;
/* look for TPM v1.2 */
sysfstpmdir = fu_common_get_path(FU_PATH_KIND_SYSFSDIR_TPM);
fn_pcrs = g_build_filename(sysfstpmdir, "tmp0", "pcrs", NULL);
if (g_file_test(fn_pcrs, G_FILE_TEST_EXISTS) && g_getenv("FWUPD_FORCE_TPM2") == NULL) {
data->tpm_device = fu_tpm_v1_device_new(fu_plugin_get_context(plugin));
g_object_set(data->tpm_device, "device-file", fn_pcrs, NULL);
if (!fu_device_probe(FU_DEVICE(data->tpm_device), error))
return FALSE;
}
/* success */
return TRUE;
}