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qemu/qga/main.c
Marc-André Lureau 9e6bdef224 util: add qemu_write_pidfile() 
There are variants of qemu_create_pidfile() in qemu-pr-helper and
qemu-ga. Let's have a common implementation in libqemuutil.

The code is initially based from pr-helper write_pidfile(), with
various improvements and suggestions from Daniel Berrangé:

  QEMU will leave the pidfile existing on disk when it exits which
  initially made me think it avoids the deletion race. The app
  managing QEMU, however, may well delete the pidfile after it has
  seen QEMU exit, and even if the app locks the pidfile before
  deleting it, there is still a race.

  eg consider the following sequence

        QEMU 1        libvirtd        QEMU 2

  1.    lock(pidfile)

  2.    exit()

  3.                 open(pidfile)

  4.                 lock(pidfile)

  5.                                  open(pidfile)

  6.                 unlink(pidfile)

  7.                 close(pidfile)

  8.                                  lock(pidfile)

  IOW, at step 8 the new QEMU has successfully acquired the lock, but
  the pidfile no longer exists on disk because it was deleted after
  the original QEMU exited.

  While we could just say no external app should ever delete the
  pidfile, I don't think that is satisfactory as people don't read
  docs, and admins don't like stale pidfiles being left around on
  disk.

  To make this robust, I think we might want to copy libvirt's
  approach to pidfile acquisition which runs in a loop and checks that
  the file on disk /after/ acquiring the lock matches the file that
  was locked. Then we could in fact safely let QEMU delete its own
  pidfiles on clean exit..

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180831145314.14736-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-02 18:47:55 +02:00

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/*
* QEMU Guest Agent
*
* Copyright IBM Corp. 2011
*
* Authors:
* Adam Litke <aglitke@linux.vnet.ibm.com>
* Michael Roth <mdroth@linux.vnet.ibm.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 <getopt.h>
#include <glib/gstdio.h>
#ifndef _WIN32
#include <syslog.h>
#include <sys/wait.h>
#endif
#include "qapi/qmp/json-parser.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qstring.h"
#include "guest-agent-core.h"
#include "qemu/module.h"
#include "qga-qapi-commands.h"
#include "qapi/qmp/qerror.h"
#include "qapi/error.h"
#include "channel.h"
#include "qemu/bswap.h"
#include "qemu/help_option.h"
#include "qemu/sockets.h"
#include "qemu/systemd.h"
#include "qemu-version.h"
#ifdef _WIN32
#include "qga/service-win32.h"
#include "qga/vss-win32.h"
#endif
#ifdef __linux__
#include <linux/fs.h>
#ifdef FIFREEZE
#define CONFIG_FSFREEZE
#endif
#endif
#ifndef _WIN32
#define QGA_VIRTIO_PATH_DEFAULT "/dev/virtio-ports/org.qemu.guest_agent.0"
#define QGA_STATE_RELATIVE_DIR "run"
#define QGA_SERIAL_PATH_DEFAULT "/dev/ttyS0"
#else
#define QGA_VIRTIO_PATH_DEFAULT "\\\\.\\Global\\org.qemu.guest_agent.0"
#define QGA_STATE_RELATIVE_DIR "qemu-ga"
#define QGA_SERIAL_PATH_DEFAULT "COM1"
#endif
#ifdef CONFIG_FSFREEZE
#define QGA_FSFREEZE_HOOK_DEFAULT CONFIG_QEMU_CONFDIR "/fsfreeze-hook"
#endif
#define QGA_SENTINEL_BYTE 0xFF
#define QGA_CONF_DEFAULT CONFIG_QEMU_CONFDIR G_DIR_SEPARATOR_S "qemu-ga.conf"
static struct {
const char *state_dir;
const char *pidfile;
} dfl_pathnames;
typedef struct GAPersistentState {
#define QGA_PSTATE_DEFAULT_FD_COUNTER 1000
int64_t fd_counter;
} GAPersistentState;
struct GAState {
JSONMessageParser parser;
GMainLoop *main_loop;
GAChannel *channel;
bool virtio; /* fastpath to check for virtio to deal with poll() quirks */
GACommandState *command_state;
GLogLevelFlags log_level;
FILE *log_file;
bool logging_enabled;
#ifdef _WIN32
GAService service;
#endif
bool delimit_response;
bool frozen;
GList *blacklist;
char *state_filepath_isfrozen;
struct {
const char *log_filepath;
const char *pid_filepath;
} deferred_options;
#ifdef CONFIG_FSFREEZE
const char *fsfreeze_hook;
#endif
gchar *pstate_filepath;
GAPersistentState pstate;
};
struct GAState *ga_state;
QmpCommandList ga_commands;
/* commands that are safe to issue while filesystems are frozen */
static const char *ga_freeze_whitelist[] = {
"guest-ping",
"guest-info",
"guest-sync",
"guest-sync-delimited",
"guest-fsfreeze-status",
"guest-fsfreeze-thaw",
NULL
};
#ifdef _WIN32
DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,
LPVOID ctx);
VOID WINAPI service_main(DWORD argc, TCHAR *argv[]);
#endif
static void
init_dfl_pathnames(void)
{
g_assert(dfl_pathnames.state_dir == NULL);
g_assert(dfl_pathnames.pidfile == NULL);
dfl_pathnames.state_dir = qemu_get_local_state_pathname(
QGA_STATE_RELATIVE_DIR);
dfl_pathnames.pidfile = qemu_get_local_state_pathname(
QGA_STATE_RELATIVE_DIR G_DIR_SEPARATOR_S "qemu-ga.pid");
}
static void quit_handler(int sig)
{
/* if we're frozen, don't exit unless we're absolutely forced to,
* because it's basically impossible for graceful exit to complete
* unless all log/pid files are on unfreezable filesystems. there's
* also a very likely chance killing the agent before unfreezing
* the filesystems is a mistake (or will be viewed as one later).
* On Windows the freeze interval is limited to 10 seconds, so
* we should quit, but first we should wait for the timeout, thaw
* the filesystem and quit.
*/
if (ga_is_frozen(ga_state)) {
#ifdef _WIN32
int i = 0;
Error *err = NULL;
HANDLE hEventTimeout;
g_debug("Thawing filesystems before exiting");
hEventTimeout = OpenEvent(EVENT_ALL_ACCESS, FALSE, EVENT_NAME_TIMEOUT);
if (hEventTimeout) {
WaitForSingleObject(hEventTimeout, 0);
CloseHandle(hEventTimeout);
}
qga_vss_fsfreeze(&i, false, &err);
if (err) {
g_debug("Error unfreezing filesystems prior to exiting: %s",
error_get_pretty(err));
error_free(err);
}
#else
return;
#endif
}
g_debug("received signal num %d, quitting", sig);
if (g_main_loop_is_running(ga_state->main_loop)) {
g_main_loop_quit(ga_state->main_loop);
}
}
#ifndef _WIN32
static gboolean register_signal_handlers(void)
{
struct sigaction sigact;
int ret;
memset(&sigact, 0, sizeof(struct sigaction));
sigact.sa_handler = quit_handler;
ret = sigaction(SIGINT, &sigact, NULL);
if (ret == -1) {
g_error("error configuring signal handler: %s", strerror(errno));
}
ret = sigaction(SIGTERM, &sigact, NULL);
if (ret == -1) {
g_error("error configuring signal handler: %s", strerror(errno));
}
sigact.sa_handler = SIG_IGN;
if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
g_error("error configuring SIGPIPE signal handler: %s",
strerror(errno));
}
return true;
}
/* TODO: use this in place of all post-fork() fclose(std*) callers */
void reopen_fd_to_null(int fd)
{
int nullfd;
nullfd = open("/dev/null", O_RDWR);
if (nullfd < 0) {
return;
}
dup2(nullfd, fd);
if (nullfd != fd) {
close(nullfd);
}
}
#endif
static void usage(const char *cmd)
{
printf(
"Usage: %s [-m <method> -p <path>] [<options>]\n"
"QEMU Guest Agent " QEMU_FULL_VERSION "\n"
QEMU_COPYRIGHT "\n"
"\n"
" -m, --method transport method: one of unix-listen, virtio-serial,\n"
" isa-serial, or vsock-listen (virtio-serial is the default)\n"
" -p, --path device/socket path (the default for virtio-serial is:\n"
" %s,\n"
" the default for isa-serial is:\n"
" %s)\n"
" -l, --logfile set logfile path, logs to stderr by default\n"
" -f, --pidfile specify pidfile (default is %s)\n"
#ifdef CONFIG_FSFREEZE
" -F, --fsfreeze-hook\n"
" enable fsfreeze hook. Accepts an optional argument that\n"
" specifies script to run on freeze/thaw. Script will be\n"
" called with 'freeze'/'thaw' arguments accordingly.\n"
" (default is %s)\n"
" If using -F with an argument, do not follow -F with a\n"
" space.\n"
" (for example: -F/var/run/fsfreezehook.sh)\n"
#endif
" -t, --statedir specify dir to store state information (absolute paths\n"
" only, default is %s)\n"
" -v, --verbose log extra debugging information\n"
" -V, --version print version information and exit\n"
" -d, --daemonize become a daemon\n"
#ifdef _WIN32
" -s, --service service commands: install, uninstall, vss-install, vss-uninstall\n"
#endif
" -b, --blacklist comma-separated list of RPCs to disable (no spaces, \"?\"\n"
" to list available RPCs)\n"
" -D, --dump-conf dump a qemu-ga config file based on current config\n"
" options / command-line parameters to stdout\n"
" -h, --help display this help and exit\n"
"\n"
QEMU_HELP_BOTTOM "\n"
, cmd, QGA_VIRTIO_PATH_DEFAULT, QGA_SERIAL_PATH_DEFAULT,
dfl_pathnames.pidfile,
#ifdef CONFIG_FSFREEZE
QGA_FSFREEZE_HOOK_DEFAULT,
#endif
dfl_pathnames.state_dir);
}
static const char *ga_log_level_str(GLogLevelFlags level)
{
switch (level & G_LOG_LEVEL_MASK) {
case G_LOG_LEVEL_ERROR:
return "error";
case G_LOG_LEVEL_CRITICAL:
return "critical";
case G_LOG_LEVEL_WARNING:
return "warning";
case G_LOG_LEVEL_MESSAGE:
return "message";
case G_LOG_LEVEL_INFO:
return "info";
case G_LOG_LEVEL_DEBUG:
return "debug";
default:
return "user";
}
}
bool ga_logging_enabled(GAState *s)
{
return s->logging_enabled;
}
void ga_disable_logging(GAState *s)
{
s->logging_enabled = false;
}
void ga_enable_logging(GAState *s)
{
s->logging_enabled = true;
}
static void ga_log(const gchar *domain, GLogLevelFlags level,
const gchar *msg, gpointer opaque)
{
GAState *s = opaque;
GTimeVal time;
const char *level_str = ga_log_level_str(level);
if (!ga_logging_enabled(s)) {
return;
}
level &= G_LOG_LEVEL_MASK;
#ifndef _WIN32
if (g_strcmp0(domain, "syslog") == 0) {
syslog(LOG_INFO, "%s: %s", level_str, msg);
} else if (level & s->log_level) {
#else
if (level & s->log_level) {
#endif
g_get_current_time(&time);
fprintf(s->log_file,
"%lu.%lu: %s: %s\n", time.tv_sec, time.tv_usec, level_str, msg);
fflush(s->log_file);
}
}
void ga_set_response_delimited(GAState *s)
{
s->delimit_response = true;
}
static FILE *ga_open_logfile(const char *logfile)
{
FILE *f;
f = fopen(logfile, "a");
if (!f) {
return NULL;
}
qemu_set_cloexec(fileno(f));
return f;
}
static gint ga_strcmp(gconstpointer str1, gconstpointer str2)
{
return strcmp(str1, str2);
}
/* disable commands that aren't safe for fsfreeze */
static void ga_disable_non_whitelisted(QmpCommand *cmd, void *opaque)
{
bool whitelisted = false;
int i = 0;
const char *name = qmp_command_name(cmd);
while (ga_freeze_whitelist[i] != NULL) {
if (strcmp(name, ga_freeze_whitelist[i]) == 0) {
whitelisted = true;
}
i++;
}
if (!whitelisted) {
g_debug("disabling command: %s", name);
qmp_disable_command(&ga_commands, name);
}
}
/* [re-]enable all commands, except those explicitly blacklisted by user */
static void ga_enable_non_blacklisted(QmpCommand *cmd, void *opaque)
{
GList *blacklist = opaque;
const char *name = qmp_command_name(cmd);
if (g_list_find_custom(blacklist, name, ga_strcmp) == NULL &&
!qmp_command_is_enabled(cmd)) {
g_debug("enabling command: %s", name);
qmp_enable_command(&ga_commands, name);
}
}
static bool ga_create_file(const char *path)
{
int fd = open(path, O_CREAT | O_WRONLY, S_IWUSR | S_IRUSR);
if (fd == -1) {
g_warning("unable to open/create file %s: %s", path, strerror(errno));
return false;
}
close(fd);
return true;
}
static bool ga_delete_file(const char *path)
{
int ret = unlink(path);
if (ret == -1) {
g_warning("unable to delete file: %s: %s", path, strerror(errno));
return false;
}
return true;
}
bool ga_is_frozen(GAState *s)
{
return s->frozen;
}
void ga_set_frozen(GAState *s)
{
if (ga_is_frozen(s)) {
return;
}
/* disable all non-whitelisted (for frozen state) commands */
qmp_for_each_command(&ga_commands, ga_disable_non_whitelisted, NULL);
g_warning("disabling logging due to filesystem freeze");
ga_disable_logging(s);
s->frozen = true;
if (!ga_create_file(s->state_filepath_isfrozen)) {
g_warning("unable to create %s, fsfreeze may not function properly",
s->state_filepath_isfrozen);
}
}
void ga_unset_frozen(GAState *s)
{
if (!ga_is_frozen(s)) {
return;
}
/* if we delayed creation/opening of pid/log files due to being
* in a frozen state at start up, do it now
*/
if (s->deferred_options.log_filepath) {
s->log_file = ga_open_logfile(s->deferred_options.log_filepath);
if (!s->log_file) {
s->log_file = stderr;
}
s->deferred_options.log_filepath = NULL;
}
ga_enable_logging(s);
g_warning("logging re-enabled due to filesystem unfreeze");
if (s->deferred_options.pid_filepath) {
Error *err = NULL;
if (!qemu_write_pidfile(s->deferred_options.pid_filepath, &err)) {
g_warning("%s", error_get_pretty(err));
error_free(err);
}
s->deferred_options.pid_filepath = NULL;
}
/* enable all disabled, non-blacklisted commands */
qmp_for_each_command(&ga_commands, ga_enable_non_blacklisted, s->blacklist);
s->frozen = false;
if (!ga_delete_file(s->state_filepath_isfrozen)) {
g_warning("unable to delete %s, fsfreeze may not function properly",
s->state_filepath_isfrozen);
}
}
#ifdef CONFIG_FSFREEZE
const char *ga_fsfreeze_hook(GAState *s)
{
return s->fsfreeze_hook;
}
#endif
static void become_daemon(const char *pidfile)
{
#ifndef _WIN32
pid_t pid, sid;
pid = fork();
if (pid < 0) {
exit(EXIT_FAILURE);
}
if (pid > 0) {
exit(EXIT_SUCCESS);
}
if (pidfile) {
Error *err = NULL;
if (!qemu_write_pidfile(pidfile, &err)) {
g_critical("%s", error_get_pretty(err));
error_free(err);
exit(EXIT_FAILURE);
}
}
umask(S_IRWXG | S_IRWXO);
sid = setsid();
if (sid < 0) {
goto fail;
}
if ((chdir("/")) < 0) {
goto fail;
}
reopen_fd_to_null(STDIN_FILENO);
reopen_fd_to_null(STDOUT_FILENO);
reopen_fd_to_null(STDERR_FILENO);
return;
fail:
if (pidfile) {
unlink(pidfile);
}
g_critical("failed to daemonize");
exit(EXIT_FAILURE);
#endif
}
static int send_response(GAState *s, QDict *payload)
{
const char *buf;
QString *payload_qstr, *response_qstr;
GIOStatus status;
g_assert(payload && s->channel);
payload_qstr = qobject_to_json(QOBJECT(payload));
if (!payload_qstr) {
return -EINVAL;
}
if (s->delimit_response) {
s->delimit_response = false;
response_qstr = qstring_new();
qstring_append_chr(response_qstr, QGA_SENTINEL_BYTE);
qstring_append(response_qstr, qstring_get_str(payload_qstr));
qobject_unref(payload_qstr);
} else {
response_qstr = payload_qstr;
}
qstring_append_chr(response_qstr, '\n');
buf = qstring_get_str(response_qstr);
status = ga_channel_write_all(s->channel, buf, strlen(buf));
qobject_unref(response_qstr);
if (status != G_IO_STATUS_NORMAL) {
return -EIO;
}
return 0;
}
static void process_command(GAState *s, QDict *req)
{
QDict *rsp;
int ret;
g_assert(req);
g_debug("processing command");
rsp = qmp_dispatch(&ga_commands, QOBJECT(req), false);
if (rsp) {
ret = send_response(s, rsp);
if (ret < 0) {
g_warning("error sending response: %s", strerror(-ret));
}
qobject_unref(rsp);
}
}
/* handle requests/control events coming in over the channel */
static void process_event(void *opaque, QObject *obj, Error *err)
{
GAState *s = opaque;
QDict *req, *rsp;
int ret;
g_debug("process_event: called");
assert(!obj != !err);
if (err) {
goto err;
}
req = qobject_to(QDict, obj);
if (!req) {
error_setg(&err, "Input must be a JSON object");
goto err;
}
if (!qdict_haskey(req, "execute")) {
g_warning("unrecognized payload format");
error_setg(&err, QERR_UNSUPPORTED);
goto err;
}
process_command(s, req);
qobject_unref(obj);
return;
err:
g_warning("failed to parse event: %s", error_get_pretty(err));
rsp = qmp_error_response(err);
ret = send_response(s, rsp);
if (ret < 0) {
g_warning("error sending error response: %s", strerror(-ret));
}
qobject_unref(rsp);
qobject_unref(obj);
}
/* false return signals GAChannel to close the current client connection */
static gboolean channel_event_cb(GIOCondition condition, gpointer data)
{
GAState *s = data;
gchar buf[QGA_READ_COUNT_DEFAULT+1];
gsize count;
GIOStatus status = ga_channel_read(s->channel, buf, QGA_READ_COUNT_DEFAULT, &count);
switch (status) {
case G_IO_STATUS_ERROR:
g_warning("error reading channel");
return false;
case G_IO_STATUS_NORMAL:
buf[count] = 0;
g_debug("read data, count: %d, data: %s", (int)count, buf);
json_message_parser_feed(&s->parser, (char *)buf, (int)count);
break;
case G_IO_STATUS_EOF:
g_debug("received EOF");
if (!s->virtio) {
return false;
}
/* fall through */
case G_IO_STATUS_AGAIN:
/* virtio causes us to spin here when no process is attached to
* host-side chardev. sleep a bit to mitigate this
*/
if (s->virtio) {
usleep(100*1000);
}
return true;
default:
g_warning("unknown channel read status, closing");
return false;
}
return true;
}
static gboolean channel_init(GAState *s, const gchar *method, const gchar *path,
int listen_fd)
{
GAChannelMethod channel_method;
if (strcmp(method, "virtio-serial") == 0) {
s->virtio = true; /* virtio requires special handling in some cases */
channel_method = GA_CHANNEL_VIRTIO_SERIAL;
} else if (strcmp(method, "isa-serial") == 0) {
channel_method = GA_CHANNEL_ISA_SERIAL;
} else if (strcmp(method, "unix-listen") == 0) {
channel_method = GA_CHANNEL_UNIX_LISTEN;
} else if (strcmp(method, "vsock-listen") == 0) {
channel_method = GA_CHANNEL_VSOCK_LISTEN;
} else {
g_critical("unsupported channel method/type: %s", method);
return false;
}
s->channel = ga_channel_new(channel_method, path, listen_fd,
channel_event_cb, s);
if (!s->channel) {
g_critical("failed to create guest agent channel");
return false;
}
return true;
}
#ifdef _WIN32
DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,
LPVOID ctx)
{
DWORD ret = NO_ERROR;
GAService *service = &ga_state->service;
switch (ctrl)
{
case SERVICE_CONTROL_STOP:
case SERVICE_CONTROL_SHUTDOWN:
quit_handler(SIGTERM);
service->status.dwCurrentState = SERVICE_STOP_PENDING;
SetServiceStatus(service->status_handle, &service->status);
break;
default:
ret = ERROR_CALL_NOT_IMPLEMENTED;
}
return ret;
}
VOID WINAPI service_main(DWORD argc, TCHAR *argv[])
{
GAService *service = &ga_state->service;
service->status_handle = RegisterServiceCtrlHandlerEx(QGA_SERVICE_NAME,
service_ctrl_handler, NULL);
if (service->status_handle == 0) {
g_critical("Failed to register extended requests function!\n");
return;
}
service->status.dwServiceType = SERVICE_WIN32;
service->status.dwCurrentState = SERVICE_RUNNING;
service->status.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;
service->status.dwWin32ExitCode = NO_ERROR;
service->status.dwServiceSpecificExitCode = NO_ERROR;
service->status.dwCheckPoint = 0;
service->status.dwWaitHint = 0;
SetServiceStatus(service->status_handle, &service->status);
g_main_loop_run(ga_state->main_loop);
service->status.dwCurrentState = SERVICE_STOPPED;
SetServiceStatus(service->status_handle, &service->status);
}
#endif
static void set_persistent_state_defaults(GAPersistentState *pstate)
{
g_assert(pstate);
pstate->fd_counter = QGA_PSTATE_DEFAULT_FD_COUNTER;
}
static void persistent_state_from_keyfile(GAPersistentState *pstate,
GKeyFile *keyfile)
{
g_assert(pstate);
g_assert(keyfile);
/* if any fields are missing, either because the file was tampered with
* by agents of chaos, or because the field wasn't present at the time the
* file was created, the best we can ever do is start over with the default
* values. so load them now, and ignore any errors in accessing key-value
* pairs
*/
set_persistent_state_defaults(pstate);
if (g_key_file_has_key(keyfile, "global", "fd_counter", NULL)) {
pstate->fd_counter =
g_key_file_get_integer(keyfile, "global", "fd_counter", NULL);
}
}
static void persistent_state_to_keyfile(const GAPersistentState *pstate,
GKeyFile *keyfile)
{
g_assert(pstate);
g_assert(keyfile);
g_key_file_set_integer(keyfile, "global", "fd_counter", pstate->fd_counter);
}
static gboolean write_persistent_state(const GAPersistentState *pstate,
const gchar *path)
{
GKeyFile *keyfile = g_key_file_new();
GError *gerr = NULL;
gboolean ret = true;
gchar *data = NULL;
gsize data_len;
g_assert(pstate);
persistent_state_to_keyfile(pstate, keyfile);
data = g_key_file_to_data(keyfile, &data_len, &gerr);
if (gerr) {
g_critical("failed to convert persistent state to string: %s",
gerr->message);
ret = false;
goto out;
}
g_file_set_contents(path, data, data_len, &gerr);
if (gerr) {
g_critical("failed to write persistent state to %s: %s",
path, gerr->message);
ret = false;
goto out;
}
out:
if (gerr) {
g_error_free(gerr);
}
if (keyfile) {
g_key_file_free(keyfile);
}
g_free(data);
return ret;
}
static gboolean read_persistent_state(GAPersistentState *pstate,
const gchar *path, gboolean frozen)
{
GKeyFile *keyfile = NULL;
GError *gerr = NULL;
struct stat st;
gboolean ret = true;
g_assert(pstate);
if (stat(path, &st) == -1) {
/* it's okay if state file doesn't exist, but any other error
* indicates a permissions issue or some other misconfiguration
* that we likely won't be able to recover from.
*/
if (errno != ENOENT) {
g_critical("unable to access state file at path %s: %s",
path, strerror(errno));
ret = false;
goto out;
}
/* file doesn't exist. initialize state to default values and
* attempt to save now. (we could wait till later when we have
* modified state we need to commit, but if there's a problem,
* such as a missing parent directory, we want to catch it now)
*
* there is a potential scenario where someone either managed to
* update the agent from a version that didn't use a key store
* while qemu-ga thought the filesystem was frozen, or
* deleted the key store prior to issuing a fsfreeze, prior
* to restarting the agent. in this case we go ahead and defer
* initial creation till we actually have modified state to
* write, otherwise fail to recover from freeze.
*/
set_persistent_state_defaults(pstate);
if (!frozen) {
ret = write_persistent_state(pstate, path);
if (!ret) {
g_critical("unable to create state file at path %s", path);
ret = false;
goto out;
}
}
ret = true;
goto out;
}
keyfile = g_key_file_new();
g_key_file_load_from_file(keyfile, path, 0, &gerr);
if (gerr) {
g_critical("error loading persistent state from path: %s, %s",
path, gerr->message);
ret = false;
goto out;
}
persistent_state_from_keyfile(pstate, keyfile);
out:
if (keyfile) {
g_key_file_free(keyfile);
}
if (gerr) {
g_error_free(gerr);
}
return ret;
}
int64_t ga_get_fd_handle(GAState *s, Error **errp)
{
int64_t handle;
g_assert(s->pstate_filepath);
/* we blacklist commands and avoid operations that potentially require
* writing to disk when we're in a frozen state. this includes opening
* new files, so we should never get here in that situation
*/
g_assert(!ga_is_frozen(s));
handle = s->pstate.fd_counter++;
/* This should never happen on a reasonable timeframe, as guest-file-open
* would have to be issued 2^63 times */
if (s->pstate.fd_counter == INT64_MAX) {
abort();
}
if (!write_persistent_state(&s->pstate, s->pstate_filepath)) {
error_setg(errp, "failed to commit persistent state to disk");
return -1;
}
return handle;
}
static void ga_print_cmd(QmpCommand *cmd, void *opaque)
{
printf("%s\n", qmp_command_name(cmd));
}
static GList *split_list(const gchar *str, const gchar *delim)
{
GList *list = NULL;
int i;
gchar **strv;
strv = g_strsplit(str, delim, -1);
for (i = 0; strv[i]; i++) {
list = g_list_prepend(list, strv[i]);
}
g_free(strv);
return list;
}
typedef struct GAConfig {
char *channel_path;
char *method;
char *log_filepath;
char *pid_filepath;
#ifdef CONFIG_FSFREEZE
char *fsfreeze_hook;
#endif
char *state_dir;
#ifdef _WIN32
const char *service;
#endif
gchar *bliststr; /* blacklist may point to this string */
GList *blacklist;
int daemonize;
GLogLevelFlags log_level;
int dumpconf;
} GAConfig;
static void config_load(GAConfig *config)
{
GError *gerr = NULL;
GKeyFile *keyfile;
const char *conf = g_getenv("QGA_CONF") ?: QGA_CONF_DEFAULT;
/* read system config */
keyfile = g_key_file_new();
if (!g_key_file_load_from_file(keyfile, conf, 0, &gerr)) {
goto end;
}
if (g_key_file_has_key(keyfile, "general", "daemon", NULL)) {
config->daemonize =
g_key_file_get_boolean(keyfile, "general", "daemon", &gerr);
}
if (g_key_file_has_key(keyfile, "general", "method", NULL)) {
config->method =
g_key_file_get_string(keyfile, "general", "method", &gerr);
}
if (g_key_file_has_key(keyfile, "general", "path", NULL)) {
config->channel_path =
g_key_file_get_string(keyfile, "general", "path", &gerr);
}
if (g_key_file_has_key(keyfile, "general", "logfile", NULL)) {
config->log_filepath =
g_key_file_get_string(keyfile, "general", "logfile", &gerr);
}
if (g_key_file_has_key(keyfile, "general", "pidfile", NULL)) {
config->pid_filepath =
g_key_file_get_string(keyfile, "general", "pidfile", &gerr);
}
#ifdef CONFIG_FSFREEZE
if (g_key_file_has_key(keyfile, "general", "fsfreeze-hook", NULL)) {
config->fsfreeze_hook =
g_key_file_get_string(keyfile,
"general", "fsfreeze-hook", &gerr);
}
#endif
if (g_key_file_has_key(keyfile, "general", "statedir", NULL)) {
config->state_dir =
g_key_file_get_string(keyfile, "general", "statedir", &gerr);
}
if (g_key_file_has_key(keyfile, "general", "verbose", NULL) &&
g_key_file_get_boolean(keyfile, "general", "verbose", &gerr)) {
/* enable all log levels */
config->log_level = G_LOG_LEVEL_MASK;
}
if (g_key_file_has_key(keyfile, "general", "blacklist", NULL)) {
config->bliststr =
g_key_file_get_string(keyfile, "general", "blacklist", &gerr);
config->blacklist = g_list_concat(config->blacklist,
split_list(config->bliststr, ","));
}
end:
g_key_file_free(keyfile);
if (gerr &&
!(gerr->domain == G_FILE_ERROR && gerr->code == G_FILE_ERROR_NOENT)) {
g_critical("error loading configuration from path: %s, %s",
QGA_CONF_DEFAULT, gerr->message);
exit(EXIT_FAILURE);
}
g_clear_error(&gerr);
}
static gchar *list_join(GList *list, const gchar separator)
{
GString *str = g_string_new("");
while (list) {
str = g_string_append(str, (gchar *)list->data);
list = g_list_next(list);
if (list) {
str = g_string_append_c(str, separator);
}
}
return g_string_free(str, FALSE);
}
static void config_dump(GAConfig *config)
{
GError *error = NULL;
GKeyFile *keyfile;
gchar *tmp;
keyfile = g_key_file_new();
g_assert(keyfile);
g_key_file_set_boolean(keyfile, "general", "daemon", config->daemonize);
g_key_file_set_string(keyfile, "general", "method", config->method);
if (config->channel_path) {
g_key_file_set_string(keyfile, "general", "path", config->channel_path);
}
if (config->log_filepath) {
g_key_file_set_string(keyfile, "general", "logfile",
config->log_filepath);
}
g_key_file_set_string(keyfile, "general", "pidfile", config->pid_filepath);
#ifdef CONFIG_FSFREEZE
if (config->fsfreeze_hook) {
g_key_file_set_string(keyfile, "general", "fsfreeze-hook",
config->fsfreeze_hook);
}
#endif
g_key_file_set_string(keyfile, "general", "statedir", config->state_dir);
g_key_file_set_boolean(keyfile, "general", "verbose",
config->log_level == G_LOG_LEVEL_MASK);
tmp = list_join(config->blacklist, ',');
g_key_file_set_string(keyfile, "general", "blacklist", tmp);
g_free(tmp);
tmp = g_key_file_to_data(keyfile, NULL, &error);
if (error) {
g_critical("Failed to dump keyfile: %s", error->message);
g_clear_error(&error);
} else {
printf("%s", tmp);
}
g_free(tmp);
g_key_file_free(keyfile);
}
static void config_parse(GAConfig *config, int argc, char **argv)
{
const char *sopt = "hVvdm:p:l:f:F::b:s:t:D";
int opt_ind = 0, ch;
const struct option lopt[] = {
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
{ "dump-conf", 0, NULL, 'D' },
{ "logfile", 1, NULL, 'l' },
{ "pidfile", 1, NULL, 'f' },
#ifdef CONFIG_FSFREEZE
{ "fsfreeze-hook", 2, NULL, 'F' },
#endif
{ "verbose", 0, NULL, 'v' },
{ "method", 1, NULL, 'm' },
{ "path", 1, NULL, 'p' },
{ "daemonize", 0, NULL, 'd' },
{ "blacklist", 1, NULL, 'b' },
#ifdef _WIN32
{ "service", 1, NULL, 's' },
#endif
{ "statedir", 1, NULL, 't' },
{ NULL, 0, NULL, 0 }
};
while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
switch (ch) {
case 'm':
g_free(config->method);
config->method = g_strdup(optarg);
break;
case 'p':
g_free(config->channel_path);
config->channel_path = g_strdup(optarg);
break;
case 'l':
g_free(config->log_filepath);
config->log_filepath = g_strdup(optarg);
break;
case 'f':
g_free(config->pid_filepath);
config->pid_filepath = g_strdup(optarg);
break;
#ifdef CONFIG_FSFREEZE
case 'F':
g_free(config->fsfreeze_hook);
config->fsfreeze_hook = g_strdup(optarg ?: QGA_FSFREEZE_HOOK_DEFAULT);
break;
#endif
case 't':
g_free(config->state_dir);
config->state_dir = g_strdup(optarg);
break;
case 'v':
/* enable all log levels */
config->log_level = G_LOG_LEVEL_MASK;
break;
case 'V':
printf("QEMU Guest Agent %s\n", QEMU_VERSION);
exit(EXIT_SUCCESS);
case 'd':
config->daemonize = 1;
break;
case 'D':
config->dumpconf = 1;
break;
case 'b': {
if (is_help_option(optarg)) {
qmp_for_each_command(&ga_commands, ga_print_cmd, NULL);
exit(EXIT_SUCCESS);
}
config->blacklist = g_list_concat(config->blacklist,
split_list(optarg, ","));
break;
}
#ifdef _WIN32
case 's':
config->service = optarg;
if (strcmp(config->service, "install") == 0) {
if (ga_install_vss_provider()) {
exit(EXIT_FAILURE);
}
if (ga_install_service(config->channel_path,
config->log_filepath, config->state_dir)) {
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
} else if (strcmp(config->service, "uninstall") == 0) {
ga_uninstall_vss_provider();
exit(ga_uninstall_service());
} else if (strcmp(config->service, "vss-install") == 0) {
if (ga_install_vss_provider()) {
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
} else if (strcmp(config->service, "vss-uninstall") == 0) {
ga_uninstall_vss_provider();
exit(EXIT_SUCCESS);
} else {
printf("Unknown service command.\n");
exit(EXIT_FAILURE);
}
break;
#endif
case 'h':
usage(argv[0]);
exit(EXIT_SUCCESS);
case '?':
g_print("Unknown option, try '%s --help' for more information.\n",
argv[0]);
exit(EXIT_FAILURE);
}
}
}
static void config_free(GAConfig *config)
{
g_free(config->method);
g_free(config->log_filepath);
g_free(config->pid_filepath);
g_free(config->state_dir);
g_free(config->channel_path);
g_free(config->bliststr);
#ifdef CONFIG_FSFREEZE
g_free(config->fsfreeze_hook);
#endif
g_list_free_full(config->blacklist, g_free);
g_free(config);
}
static bool check_is_frozen(GAState *s)
{
#ifndef _WIN32
/* check if a previous instance of qemu-ga exited with filesystems' state
* marked as frozen. this could be a stale value (a non-qemu-ga process
* or reboot may have since unfrozen them), but better to require an
* uneeded unfreeze than to risk hanging on start-up
*/
struct stat st;
if (stat(s->state_filepath_isfrozen, &st) == -1) {
/* it's okay if the file doesn't exist, but if we can't access for
* some other reason, such as permissions, there's a configuration
* that needs to be addressed. so just bail now before we get into
* more trouble later
*/
if (errno != ENOENT) {
g_critical("unable to access state file at path %s: %s",
s->state_filepath_isfrozen, strerror(errno));
return EXIT_FAILURE;
}
} else {
g_warning("previous instance appears to have exited with frozen"
" filesystems. deferring logging/pidfile creation and"
" disabling non-fsfreeze-safe commands until"
" guest-fsfreeze-thaw is issued, or filesystems are"
" manually unfrozen and the file %s is removed",
s->state_filepath_isfrozen);
return true;
}
#endif
return false;
}
static int run_agent(GAState *s, GAConfig *config, int socket_activation)
{
ga_state = s;
g_log_set_default_handler(ga_log, s);
g_log_set_fatal_mask(NULL, G_LOG_LEVEL_ERROR);
ga_enable_logging(s);
#ifdef _WIN32
/* On win32 the state directory is application specific (be it the default
* or a user override). We got past the command line parsing; let's create
* the directory (with any intermediate directories). If we run into an
* error later on, we won't try to clean up the directory, it is considered
* persistent.
*/
if (g_mkdir_with_parents(config->state_dir, S_IRWXU) == -1) {
g_critical("unable to create (an ancestor of) the state directory"
" '%s': %s", config->state_dir, strerror(errno));
return EXIT_FAILURE;
}
#endif
if (ga_is_frozen(s)) {
if (config->daemonize) {
/* delay opening/locking of pidfile till filesystems are unfrozen */
s->deferred_options.pid_filepath = config->pid_filepath;
become_daemon(NULL);
}
if (config->log_filepath) {
/* delay opening the log file till filesystems are unfrozen */
s->deferred_options.log_filepath = config->log_filepath;
}
ga_disable_logging(s);
qmp_for_each_command(&ga_commands, ga_disable_non_whitelisted, NULL);
} else {
if (config->daemonize) {
become_daemon(config->pid_filepath);
}
if (config->log_filepath) {
FILE *log_file = ga_open_logfile(config->log_filepath);
if (!log_file) {
g_critical("unable to open specified log file: %s",
strerror(errno));
return EXIT_FAILURE;
}
s->log_file = log_file;
}
}
/* load persistent state from disk */
if (!read_persistent_state(&s->pstate,
s->pstate_filepath,
ga_is_frozen(s))) {
g_critical("failed to load persistent state");
return EXIT_FAILURE;
}
config->blacklist = ga_command_blacklist_init(config->blacklist);
if (config->blacklist) {
GList *l = config->blacklist;
s->blacklist = config->blacklist;
do {
g_debug("disabling command: %s", (char *)l->data);
qmp_disable_command(&ga_commands, l->data);
l = g_list_next(l);
} while (l);
}
s->command_state = ga_command_state_new();
ga_command_state_init(s, s->command_state);
ga_command_state_init_all(s->command_state);
json_message_parser_init(&s->parser, process_event, s, NULL);
#ifndef _WIN32
if (!register_signal_handlers()) {
g_critical("failed to register signal handlers");
return EXIT_FAILURE;
}
#endif
s->main_loop = g_main_loop_new(NULL, false);
if (!channel_init(ga_state, config->method, config->channel_path,
socket_activation ? FIRST_SOCKET_ACTIVATION_FD : -1)) {
g_critical("failed to initialize guest agent channel");
return EXIT_FAILURE;
}
#ifndef _WIN32
g_main_loop_run(ga_state->main_loop);
#else
if (config->daemonize) {
SERVICE_TABLE_ENTRY service_table[] = {
{ (char *)QGA_SERVICE_NAME, service_main }, { NULL, NULL } };
StartServiceCtrlDispatcher(service_table);
} else {
g_main_loop_run(ga_state->main_loop);
}
#endif
return EXIT_SUCCESS;
}
int main(int argc, char **argv)
{
int ret = EXIT_SUCCESS;
GAState *s = g_new0(GAState, 1);
GAConfig *config = g_new0(GAConfig, 1);
int socket_activation;
config->log_level = G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL;
qga_qmp_init_marshal(&ga_commands);
init_dfl_pathnames();
config_load(config);
config_parse(config, argc, argv);
if (config->pid_filepath == NULL) {
config->pid_filepath = g_strdup(dfl_pathnames.pidfile);
}
if (config->state_dir == NULL) {
config->state_dir = g_strdup(dfl_pathnames.state_dir);
}
if (config->method == NULL) {
config->method = g_strdup("virtio-serial");
}
socket_activation = check_socket_activation();
if (socket_activation > 1) {
g_critical("qemu-ga only supports listening on one socket");
ret = EXIT_FAILURE;
goto end;
}
if (socket_activation) {
SocketAddress *addr;
g_free(config->method);
g_free(config->channel_path);
config->method = NULL;
config->channel_path = NULL;
addr = socket_local_address(FIRST_SOCKET_ACTIVATION_FD, NULL);
if (addr) {
if (addr->type == SOCKET_ADDRESS_TYPE_UNIX) {
config->method = g_strdup("unix-listen");
} else if (addr->type == SOCKET_ADDRESS_TYPE_VSOCK) {
config->method = g_strdup("vsock-listen");
}
qapi_free_SocketAddress(addr);
}
if (!config->method) {
g_critical("unsupported listen fd type");
ret = EXIT_FAILURE;
goto end;
}
} else if (config->channel_path == NULL) {
if (strcmp(config->method, "virtio-serial") == 0) {
/* try the default path for the virtio-serial port */
config->channel_path = g_strdup(QGA_VIRTIO_PATH_DEFAULT);
} else if (strcmp(config->method, "isa-serial") == 0) {
/* try the default path for the serial port - COM1 */
config->channel_path = g_strdup(QGA_SERIAL_PATH_DEFAULT);
} else {
g_critical("must specify a path for this channel");
ret = EXIT_FAILURE;
goto end;
}
}
s->log_level = config->log_level;
s->log_file = stderr;
#ifdef CONFIG_FSFREEZE
s->fsfreeze_hook = config->fsfreeze_hook;
#endif
s->pstate_filepath = g_strdup_printf("%s/qga.state", config->state_dir);
s->state_filepath_isfrozen = g_strdup_printf("%s/qga.state.isfrozen",
config->state_dir);
s->frozen = check_is_frozen(s);
if (config->dumpconf) {
config_dump(config);
goto end;
}
ret = run_agent(s, config, socket_activation);
end:
if (s->command_state) {
ga_command_state_cleanup_all(s->command_state);
ga_command_state_free(s->command_state);
json_message_parser_destroy(&s->parser);
}
if (s->channel) {
ga_channel_free(s->channel);
}
g_free(s->pstate_filepath);
g_free(s->state_filepath_isfrozen);
if (config->daemonize) {
unlink(config->pid_filepath);
}
config_free(config);
if (s->main_loop) {
g_main_loop_unref(s->main_loop);
}
g_free(s);
return ret;
}
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