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xemu/backends/dbus-vmstate.c
Markus Armbruster 166a1cf404 backends/dbus-vmstate: Fix short read error handling 
When dbus_vmstate_post_load() fails, it complains to stderr.  Except
on short read, where it checks with g_return_val_if_fail().  This
fails silently if G_DISABLE_CHECKS is undefined (it should be), or
else pads the short read with uninitialized bytes.

Replace g_return_val_if_fail() by a proper error check.

Fixes: 5010cec2bc
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210126124240.2081959-2-armbru@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-03-09 21:41:04 +01:00

504 lines
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/*
* QEMU dbus-vmstate
*
* Copyright (C) 2019 Red Hat Inc
*
* Authors:
* Marc-André Lureau <marcandre.lureau@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/units.h"
#include "qemu/dbus.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qom/object_interfaces.h"
#include "qapi/qmp/qerror.h"
#include "migration/vmstate.h"
#include "trace.h"
#include "qom/object.h"
#define TYPE_DBUS_VMSTATE "dbus-vmstate"
OBJECT_DECLARE_SIMPLE_TYPE(DBusVMState,
DBUS_VMSTATE)
struct DBusVMState {
Object parent;
GDBusConnection *bus;
char *dbus_addr;
char *id_list;
uint32_t data_size;
uint8_t *data;
};
static const GDBusPropertyInfo vmstate_property_info[] = {
{ -1, (char *) "Id", (char *) "s",
G_DBUS_PROPERTY_INFO_FLAGS_READABLE, NULL },
};
static const GDBusPropertyInfo * const vmstate_property_info_pointers[] = {
&vmstate_property_info[0],
NULL
};
static const GDBusInterfaceInfo vmstate1_interface_info = {
-1,
(char *) "org.qemu.VMState1",
(GDBusMethodInfo **) NULL,
(GDBusSignalInfo **) NULL,
(GDBusPropertyInfo **) &vmstate_property_info_pointers,
NULL,
};
#define DBUS_VMSTATE_SIZE_LIMIT (1 * MiB)
static GHashTable *
get_id_list_set(DBusVMState *self)
{
g_auto(GStrv) ids = NULL;
g_autoptr(GHashTable) set = NULL;
int i;
if (!self->id_list) {
return NULL;
}
ids = g_strsplit(self->id_list, ",", -1);
set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
for (i = 0; ids[i]; i++) {
g_hash_table_add(set, ids[i]);
ids[i] = NULL;
}
return g_steal_pointer(&set);
}
static GHashTable *
dbus_get_proxies(DBusVMState *self, GError **err)
{
g_autoptr(GHashTable) proxies = NULL;
g_autoptr(GHashTable) ids = NULL;
g_auto(GStrv) names = NULL;
Error *error = NULL;
size_t i;
ids = get_id_list_set(self);
proxies = g_hash_table_new_full(g_str_hash, g_str_equal,
g_free, g_object_unref);
names = qemu_dbus_get_queued_owners(self->bus, "org.qemu.VMState1", &error);
if (!names) {
g_set_error(err, G_IO_ERROR, G_IO_ERROR_FAILED, "%s",
error_get_pretty(error));
error_free(error);
return NULL;
}
for (i = 0; names[i]; i++) {
g_autoptr(GDBusProxy) proxy = NULL;
g_autoptr(GVariant) result = NULL;
g_autofree char *id = NULL;
size_t size;
proxy = g_dbus_proxy_new_sync(self->bus, G_DBUS_PROXY_FLAGS_NONE,
(GDBusInterfaceInfo *) &vmstate1_interface_info,
names[i],
"/org/qemu/VMState1",
"org.qemu.VMState1",
NULL, err);
if (!proxy) {
return NULL;
}
result = g_dbus_proxy_get_cached_property(proxy, "Id");
if (!result) {
g_set_error_literal(err, G_IO_ERROR, G_IO_ERROR_FAILED,
"VMState Id property is missing.");
return NULL;
}
id = g_variant_dup_string(result, &size);
if (ids && !g_hash_table_remove(ids, id)) {
g_clear_pointer(&id, g_free);
g_clear_object(&proxy);
continue;
}
if (size == 0 || size >= 256) {
g_set_error(err, G_IO_ERROR, G_IO_ERROR_FAILED,
"VMState Id '%s' is invalid.", id);
return NULL;
}
if (!g_hash_table_insert(proxies, id, proxy)) {
g_set_error(err, G_IO_ERROR, G_IO_ERROR_FAILED,
"Duplicated VMState Id '%s'", id);
return NULL;
}
id = NULL;
proxy = NULL;
g_clear_pointer(&result, g_variant_unref);
}
if (ids) {
g_autofree char **left = NULL;
left = (char **)g_hash_table_get_keys_as_array(ids, NULL);
if (*left) {
g_autofree char *leftids = g_strjoinv(",", left);
g_set_error(err, G_IO_ERROR, G_IO_ERROR_FAILED,
"Required VMState Id are missing: %s", leftids);
return NULL;
}
}
return g_steal_pointer(&proxies);
}
static int
dbus_load_state_proxy(GDBusProxy *proxy, const uint8_t *data, size_t size)
{
g_autoptr(GError) err = NULL;
g_autoptr(GVariant) result = NULL;
g_autoptr(GVariant) value = NULL;
value = g_variant_new_fixed_array(G_VARIANT_TYPE_BYTE,
data, size, sizeof(char));
result = g_dbus_proxy_call_sync(proxy, "Load",
g_variant_new("(@ay)",
g_steal_pointer(&value)),
G_DBUS_CALL_FLAGS_NO_AUTO_START,
-1, NULL, &err);
if (!result) {
error_report("%s: Failed to Load: %s", __func__, err->message);
return -1;
}
return 0;
}
static int dbus_vmstate_post_load(void *opaque, int version_id)
{
DBusVMState *self = DBUS_VMSTATE(opaque);
g_autoptr(GInputStream) m = NULL;
g_autoptr(GDataInputStream) s = NULL;
g_autoptr(GError) err = NULL;
g_autoptr(GHashTable) proxies = NULL;
uint32_t nelem;
trace_dbus_vmstate_post_load(version_id);
proxies = dbus_get_proxies(self, &err);
if (!proxies) {
error_report("%s: Failed to get proxies: %s", __func__, err->message);
return -1;
}
m = g_memory_input_stream_new_from_data(self->data, self->data_size, NULL);
s = g_data_input_stream_new(m);
g_data_input_stream_set_byte_order(s, G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
nelem = g_data_input_stream_read_uint32(s, NULL, &err);
if (err) {
goto error;
}
while (nelem > 0) {
GDBusProxy *proxy = NULL;
uint32_t len;
gsize bytes_read, avail;
char id[256];
len = g_data_input_stream_read_uint32(s, NULL, &err);
if (err) {
goto error;
}
if (len >= 256) {
error_report("%s: Invalid DBus vmstate proxy name %u",
__func__, len);
return -1;
}
if (!g_input_stream_read_all(G_INPUT_STREAM(s), id, len,
&bytes_read, NULL, &err)) {
goto error;
}
if (bytes_read != len) {
error_report("%s: Short read", __func__);
return -1;
}
id[len] = 0;
trace_dbus_vmstate_loading(id);
proxy = g_hash_table_lookup(proxies, id);
if (!proxy) {
error_report("%s: Failed to find proxy Id '%s'", __func__, id);
return -1;
}
len = g_data_input_stream_read_uint32(s, NULL, &err);
avail = g_buffered_input_stream_get_available(
G_BUFFERED_INPUT_STREAM(s));
if (len > DBUS_VMSTATE_SIZE_LIMIT || len > avail) {
error_report("%s: Invalid vmstate size: %u", __func__, len);
return -1;
}
if (dbus_load_state_proxy(proxy,
g_buffered_input_stream_peek_buffer(G_BUFFERED_INPUT_STREAM(s),
NULL),
len) < 0) {
error_report("%s: Failed to restore Id '%s'", __func__, id);
return -1;
}
if (!g_seekable_seek(G_SEEKABLE(s), len, G_SEEK_CUR, NULL, &err)) {
goto error;
}
nelem -= 1;
}
return 0;
error:
error_report("%s: Failed to read from stream: %s", __func__, err->message);
return -1;
}
static void
dbus_save_state_proxy(gpointer key,
gpointer value,
gpointer user_data)
{
GDataOutputStream *s = user_data;
const char *id = key;
GDBusProxy *proxy = value;
g_autoptr(GVariant) result = NULL;
g_autoptr(GVariant) child = NULL;
g_autoptr(GError) err = NULL;
const uint8_t *data;
gsize size;
trace_dbus_vmstate_saving(id);
result = g_dbus_proxy_call_sync(proxy, "Save",
NULL, G_DBUS_CALL_FLAGS_NO_AUTO_START,
-1, NULL, &err);
if (!result) {
error_report("%s: Failed to Save: %s", __func__, err->message);
return;
}
child = g_variant_get_child_value(result, 0);
data = g_variant_get_fixed_array(child, &size, sizeof(char));
if (!data) {
error_report("%s: Failed to Save: not a byte array", __func__);
return;
}
if (size > DBUS_VMSTATE_SIZE_LIMIT) {
error_report("%s: Too large vmstate data to save: %zu",
__func__, (size_t)size);
return;
}
if (!g_data_output_stream_put_uint32(s, strlen(id), NULL, &err) ||
!g_data_output_stream_put_string(s, id, NULL, &err) ||
!g_data_output_stream_put_uint32(s, size, NULL, &err) ||
!g_output_stream_write_all(G_OUTPUT_STREAM(s),
data, size, NULL, NULL, &err)) {
error_report("%s: Failed to write to stream: %s",
__func__, err->message);
}
}
static int dbus_vmstate_pre_save(void *opaque)
{
DBusVMState *self = DBUS_VMSTATE(opaque);
g_autoptr(GOutputStream) m = NULL;
g_autoptr(GDataOutputStream) s = NULL;
g_autoptr(GHashTable) proxies = NULL;
g_autoptr(GError) err = NULL;
trace_dbus_vmstate_pre_save();
proxies = dbus_get_proxies(self, &err);
if (!proxies) {
error_report("%s: Failed to get proxies: %s", __func__, err->message);
return -1;
}
m = g_memory_output_stream_new_resizable();
s = g_data_output_stream_new(m);
g_data_output_stream_set_byte_order(s, G_DATA_STREAM_BYTE_ORDER_BIG_ENDIAN);
if (!g_data_output_stream_put_uint32(s, g_hash_table_size(proxies),
NULL, &err)) {
error_report("%s: Failed to write to stream: %s",
__func__, err->message);
return -1;
}
g_hash_table_foreach(proxies, dbus_save_state_proxy, s);
if (g_memory_output_stream_get_size(G_MEMORY_OUTPUT_STREAM(m))
> UINT32_MAX) {
error_report("%s: DBus vmstate buffer is too large", __func__);
return -1;
}
if (!g_output_stream_close(G_OUTPUT_STREAM(m), NULL, &err)) {
error_report("%s: Failed to close stream: %s", __func__, err->message);
return -1;
}
g_free(self->data);
self->data_size =
g_memory_output_stream_get_size(G_MEMORY_OUTPUT_STREAM(m));
self->data =
g_memory_output_stream_steal_data(G_MEMORY_OUTPUT_STREAM(m));
return 0;
}
static const VMStateDescription dbus_vmstate = {
.name = TYPE_DBUS_VMSTATE,
.version_id = 0,
.pre_save = dbus_vmstate_pre_save,
.post_load = dbus_vmstate_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT32(data_size, DBusVMState),
VMSTATE_VBUFFER_ALLOC_UINT32(data, DBusVMState, 0, 0, data_size),
VMSTATE_END_OF_LIST()
}
};
static void
dbus_vmstate_complete(UserCreatable *uc, Error **errp)
{
DBusVMState *self = DBUS_VMSTATE(uc);
g_autoptr(GError) err = NULL;
if (!object_resolve_path_type("", TYPE_DBUS_VMSTATE, NULL)) {
error_setg(errp, "There is already an instance of %s",
TYPE_DBUS_VMSTATE);
return;
}
if (!self->dbus_addr) {
error_setg(errp, QERR_MISSING_PARAMETER, "addr");
return;
}
self->bus = g_dbus_connection_new_for_address_sync(self->dbus_addr,
G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_CLIENT |
G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION,
NULL, NULL, &err);
if (err) {
error_setg(errp, "failed to connect to DBus: '%s'", err->message);
return;
}
if (vmstate_register(VMSTATE_IF(self), VMSTATE_INSTANCE_ID_ANY,
&dbus_vmstate, self) < 0) {
error_setg(errp, "Failed to register vmstate");
}
}
static void
dbus_vmstate_finalize(Object *o)
{
DBusVMState *self = DBUS_VMSTATE(o);
vmstate_unregister(VMSTATE_IF(self), &dbus_vmstate, self);
g_clear_object(&self->bus);
g_free(self->dbus_addr);
g_free(self->id_list);
g_free(self->data);
}
static char *
get_dbus_addr(Object *o, Error **errp)
{
DBusVMState *self = DBUS_VMSTATE(o);
return g_strdup(self->dbus_addr);
}
static void
set_dbus_addr(Object *o, const char *str, Error **errp)
{
DBusVMState *self = DBUS_VMSTATE(o);
g_free(self->dbus_addr);
self->dbus_addr = g_strdup(str);
}
static char *
get_id_list(Object *o, Error **errp)
{
DBusVMState *self = DBUS_VMSTATE(o);
return g_strdup(self->id_list);
}
static void
set_id_list(Object *o, const char *str, Error **errp)
{
DBusVMState *self = DBUS_VMSTATE(o);
g_free(self->id_list);
self->id_list = g_strdup(str);
}
static char *
dbus_vmstate_get_id(VMStateIf *vmif)
{
return g_strdup(TYPE_DBUS_VMSTATE);
}
static void
dbus_vmstate_class_init(ObjectClass *oc, void *data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
VMStateIfClass *vc = VMSTATE_IF_CLASS(oc);
ucc->complete = dbus_vmstate_complete;
vc->get_id = dbus_vmstate_get_id;
object_class_property_add_str(oc, "addr",
get_dbus_addr, set_dbus_addr);
object_class_property_add_str(oc, "id-list",
get_id_list, set_id_list);
}
static const TypeInfo dbus_vmstate_info = {
.name = TYPE_DBUS_VMSTATE,
.parent = TYPE_OBJECT,
.instance_size = sizeof(DBusVMState),
.instance_finalize = dbus_vmstate_finalize,
.class_init = dbus_vmstate_class_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ TYPE_VMSTATE_IF },
{ }
}
};
static void
register_types(void)
{
type_register_static(&dbus_vmstate_info);
}
type_init(register_types);
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