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qemu/qga/commands.c
Michal Privoznik 0d3a8f32b1 qga: Use qemu_get_host_name() instead of g_get_host_name() 
Problem with g_get_host_name() is that on the first call it saves
the hostname into a global variable and from then on, every
subsequent call returns the saved hostname. Even if the hostname
changes. This doesn't play nicely with guest agent, because if
the hostname is acquired before the guest is set up (e.g. on the
first boot, or before DHCP) we will report old, invalid hostname.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1845127

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2020-07-13 17:44:58 -05:00

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/*
* QEMU Guest Agent common/cross-platform command implementations
*
* Copyright IBM Corp. 2012
*
* Authors:
* 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 "qemu/units.h"
#include "guest-agent-core.h"
#include "qga-qapi-commands.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qemu/base64.h"
#include "qemu/cutils.h"
#include "qemu/atomic.h"
#include "commands-common.h"
/* Maximum captured guest-exec out_data/err_data - 16MB */
#define GUEST_EXEC_MAX_OUTPUT (16*1024*1024)
/* Allocation and I/O buffer for reading guest-exec out_data/err_data - 4KB */
#define GUEST_EXEC_IO_SIZE (4*1024)
/*
* Maximum file size to read - 48MB
*
* (48MB + Base64 3:4 overhead = JSON parser 64 MB limit)
*/
#define GUEST_FILE_READ_COUNT_MAX (48 * MiB)
/* Note: in some situations, like with the fsfreeze, logging may be
* temporarilly disabled. if it is necessary that a command be able
* to log for accounting purposes, check ga_logging_enabled() beforehand,
* and use the QERR_QGA_LOGGING_DISABLED to generate an error
*/
void slog(const gchar *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
g_logv("syslog", G_LOG_LEVEL_INFO, fmt, ap);
va_end(ap);
}
int64_t qmp_guest_sync_delimited(int64_t id, Error **errp)
{
ga_set_response_delimited(ga_state);
return id;
}
int64_t qmp_guest_sync(int64_t id, Error **errp)
{
return id;
}
void qmp_guest_ping(Error **errp)
{
slog("guest-ping called");
}
static void qmp_command_info(const QmpCommand *cmd, void *opaque)
{
GuestAgentInfo *info = opaque;
GuestAgentCommandInfo *cmd_info;
GuestAgentCommandInfoList *cmd_info_list;
cmd_info = g_new0(GuestAgentCommandInfo, 1);
cmd_info->name = g_strdup(qmp_command_name(cmd));
cmd_info->enabled = qmp_command_is_enabled(cmd);
cmd_info->success_response = qmp_has_success_response(cmd);
cmd_info_list = g_new0(GuestAgentCommandInfoList, 1);
cmd_info_list->value = cmd_info;
cmd_info_list->next = info->supported_commands;
info->supported_commands = cmd_info_list;
}
struct GuestAgentInfo *qmp_guest_info(Error **errp)
{
GuestAgentInfo *info = g_new0(GuestAgentInfo, 1);
info->version = g_strdup(QEMU_VERSION);
qmp_for_each_command(&ga_commands, qmp_command_info, info);
return info;
}
struct GuestExecIOData {
guchar *data;
gsize size;
gsize length;
bool closed;
bool truncated;
const char *name;
};
typedef struct GuestExecIOData GuestExecIOData;
struct GuestExecInfo {
GPid pid;
int64_t pid_numeric;
gint status;
bool has_output;
bool finished;
GuestExecIOData in;
GuestExecIOData out;
GuestExecIOData err;
QTAILQ_ENTRY(GuestExecInfo) next;
};
typedef struct GuestExecInfo GuestExecInfo;
static struct {
QTAILQ_HEAD(, GuestExecInfo) processes;
} guest_exec_state = {
.processes = QTAILQ_HEAD_INITIALIZER(guest_exec_state.processes),
};
static int64_t gpid_to_int64(GPid pid)
{
#ifdef G_OS_WIN32
return GetProcessId(pid);
#else
return (int64_t)pid;
#endif
}
static GuestExecInfo *guest_exec_info_add(GPid pid)
{
GuestExecInfo *gei;
gei = g_new0(GuestExecInfo, 1);
gei->pid = pid;
gei->pid_numeric = gpid_to_int64(pid);
QTAILQ_INSERT_TAIL(&guest_exec_state.processes, gei, next);
return gei;
}
static GuestExecInfo *guest_exec_info_find(int64_t pid_numeric)
{
GuestExecInfo *gei;
QTAILQ_FOREACH(gei, &guest_exec_state.processes, next) {
if (gei->pid_numeric == pid_numeric) {
return gei;
}
}
return NULL;
}
GuestExecStatus *qmp_guest_exec_status(int64_t pid, Error **errp)
{
GuestExecInfo *gei;
GuestExecStatus *ges;
slog("guest-exec-status called, pid: %u", (uint32_t)pid);
gei = guest_exec_info_find(pid);
if (gei == NULL) {
error_setg(errp, QERR_INVALID_PARAMETER, "pid");
return NULL;
}
ges = g_new0(GuestExecStatus, 1);
bool finished = atomic_mb_read(&gei->finished);
/* need to wait till output channels are closed
* to be sure we captured all output at this point */
if (gei->has_output) {
finished = finished && atomic_mb_read(&gei->out.closed);
finished = finished && atomic_mb_read(&gei->err.closed);
}
ges->exited = finished;
if (finished) {
/* Glib has no portable way to parse exit status.
* On UNIX, we can get either exit code from normal termination
* or signal number.
* On Windows, it is either the same exit code or the exception
* value for an unhandled exception that caused the process
* to terminate.
* See MSDN for GetExitCodeProcess() and ntstatus.h for possible
* well-known codes, e.g. C0000005 ACCESS_DENIED - analog of SIGSEGV
* References:
* https://msdn.microsoft.com/en-us/library/windows/desktop/ms683189(v=vs.85).aspx
* https://msdn.microsoft.com/en-us/library/aa260331(v=vs.60).aspx
*/
#ifdef G_OS_WIN32
/* Additionally WIN32 does not provide any additional information
* on whether the child exited or terminated via signal.
* We use this simple range check to distinguish application exit code
* (usually value less then 256) and unhandled exception code with
* ntstatus (always value greater then 0xC0000005). */
if ((uint32_t)gei->status < 0xC0000000U) {
ges->has_exitcode = true;
ges->exitcode = gei->status;
} else {
ges->has_signal = true;
ges->signal = gei->status;
}
#else
if (WIFEXITED(gei->status)) {
ges->has_exitcode = true;
ges->exitcode = WEXITSTATUS(gei->status);
} else if (WIFSIGNALED(gei->status)) {
ges->has_signal = true;
ges->signal = WTERMSIG(gei->status);
}
#endif
if (gei->out.length > 0) {
ges->has_out_data = true;
ges->out_data = g_base64_encode(gei->out.data, gei->out.length);
g_free(gei->out.data);
ges->has_out_truncated = gei->out.truncated;
}
if (gei->err.length > 0) {
ges->has_err_data = true;
ges->err_data = g_base64_encode(gei->err.data, gei->err.length);
g_free(gei->err.data);
ges->has_err_truncated = gei->err.truncated;
}
QTAILQ_REMOVE(&guest_exec_state.processes, gei, next);
g_free(gei);
}
return ges;
}
/* Get environment variables or arguments array for execve(). */
static char **guest_exec_get_args(const strList *entry, bool log)
{
const strList *it;
int count = 1, i = 0; /* reserve for NULL terminator */
char **args;
char *str; /* for logging array of arguments */
size_t str_size = 1;
for (it = entry; it != NULL; it = it->next) {
count++;
str_size += 1 + strlen(it->value);
}
str = g_malloc(str_size);
*str = 0;
args = g_malloc(count * sizeof(char *));
for (it = entry; it != NULL; it = it->next) {
args[i++] = it->value;
pstrcat(str, str_size, it->value);
if (it->next) {
pstrcat(str, str_size, " ");
}
}
args[i] = NULL;
if (log) {
slog("guest-exec called: \"%s\"", str);
}
g_free(str);
return args;
}
static void guest_exec_child_watch(GPid pid, gint status, gpointer data)
{
GuestExecInfo *gei = (GuestExecInfo *)data;
g_debug("guest_exec_child_watch called, pid: %d, status: %u",
(int32_t)gpid_to_int64(pid), (uint32_t)status);
gei->status = status;
atomic_mb_set(&gei->finished, true);
g_spawn_close_pid(pid);
}
/** Reset ignored signals back to default. */
static void guest_exec_task_setup(gpointer data)
{
#if !defined(G_OS_WIN32)
struct sigaction sigact;
memset(&sigact, 0, sizeof(struct sigaction));
sigact.sa_handler = SIG_DFL;
if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
slog("sigaction() failed to reset child process's SIGPIPE: %s",
strerror(errno));
}
#endif
}
static gboolean guest_exec_input_watch(GIOChannel *ch,
GIOCondition cond, gpointer p_)
{
GuestExecIOData *p = (GuestExecIOData *)p_;
gsize bytes_written = 0;
GIOStatus status;
GError *gerr = NULL;
/* nothing left to write */
if (p->size == p->length) {
goto done;
}
status = g_io_channel_write_chars(ch, (gchar *)p->data + p->length,
p->size - p->length, &bytes_written, &gerr);
/* can be not 0 even if not G_IO_STATUS_NORMAL */
if (bytes_written != 0) {
p->length += bytes_written;
}
/* continue write, our callback will be called again */
if (status == G_IO_STATUS_NORMAL || status == G_IO_STATUS_AGAIN) {
return true;
}
if (gerr) {
g_warning("qga: i/o error writing to input_data channel: %s",
gerr->message);
g_error_free(gerr);
}
done:
g_io_channel_shutdown(ch, true, NULL);
g_io_channel_unref(ch);
atomic_mb_set(&p->closed, true);
g_free(p->data);
return false;
}
static gboolean guest_exec_output_watch(GIOChannel *ch,
GIOCondition cond, gpointer p_)
{
GuestExecIOData *p = (GuestExecIOData *)p_;
gsize bytes_read;
GIOStatus gstatus;
if (cond == G_IO_HUP || cond == G_IO_ERR) {
goto close;
}
if (p->size == p->length) {
gpointer t = NULL;
if (!p->truncated && p->size < GUEST_EXEC_MAX_OUTPUT) {
t = g_try_realloc(p->data, p->size + GUEST_EXEC_IO_SIZE);
}
if (t == NULL) {
/* ignore truncated output */
gchar buf[GUEST_EXEC_IO_SIZE];
p->truncated = true;
gstatus = g_io_channel_read_chars(ch, buf, sizeof(buf),
&bytes_read, NULL);
if (gstatus == G_IO_STATUS_EOF || gstatus == G_IO_STATUS_ERROR) {
goto close;
}
return true;
}
p->size += GUEST_EXEC_IO_SIZE;
p->data = t;
}
/* Calling read API once.
* On next available data our callback will be called again */
gstatus = g_io_channel_read_chars(ch, (gchar *)p->data + p->length,
p->size - p->length, &bytes_read, NULL);
if (gstatus == G_IO_STATUS_EOF || gstatus == G_IO_STATUS_ERROR) {
goto close;
}
p->length += bytes_read;
return true;
close:
g_io_channel_shutdown(ch, true, NULL);
g_io_channel_unref(ch);
atomic_mb_set(&p->closed, true);
return false;
}
GuestExec *qmp_guest_exec(const char *path,
bool has_arg, strList *arg,
bool has_env, strList *env,
bool has_input_data, const char *input_data,
bool has_capture_output, bool capture_output,
Error **errp)
{
GPid pid;
GuestExec *ge = NULL;
GuestExecInfo *gei;
char **argv, **envp;
strList arglist;
gboolean ret;
GError *gerr = NULL;
gint in_fd, out_fd, err_fd;
GIOChannel *in_ch, *out_ch, *err_ch;
GSpawnFlags flags;
bool has_output = (has_capture_output && capture_output);
uint8_t *input = NULL;
size_t ninput = 0;
arglist.value = (char *)path;
arglist.next = has_arg ? arg : NULL;
if (has_input_data) {
input = qbase64_decode(input_data, -1, &ninput, errp);
if (!input) {
return NULL;
}
}
argv = guest_exec_get_args(&arglist, true);
envp = has_env ? guest_exec_get_args(env, false) : NULL;
flags = G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD |
G_SPAWN_SEARCH_PATH_FROM_ENVP;
if (!has_output) {
flags |= G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL;
}
ret = g_spawn_async_with_pipes(NULL, argv, envp, flags,
guest_exec_task_setup, NULL, &pid, has_input_data ? &in_fd : NULL,
has_output ? &out_fd : NULL, has_output ? &err_fd : NULL, &gerr);
if (!ret) {
error_setg(errp, QERR_QGA_COMMAND_FAILED, gerr->message);
g_error_free(gerr);
goto done;
}
ge = g_new0(GuestExec, 1);
ge->pid = gpid_to_int64(pid);
gei = guest_exec_info_add(pid);
gei->has_output = has_output;
g_child_watch_add(pid, guest_exec_child_watch, gei);
if (has_input_data) {
gei->in.data = input;
gei->in.size = ninput;
#ifdef G_OS_WIN32
in_ch = g_io_channel_win32_new_fd(in_fd);
#else
in_ch = g_io_channel_unix_new(in_fd);
#endif
g_io_channel_set_encoding(in_ch, NULL, NULL);
g_io_channel_set_buffered(in_ch, false);
g_io_channel_set_flags(in_ch, G_IO_FLAG_NONBLOCK, NULL);
g_io_channel_set_close_on_unref(in_ch, true);
g_io_add_watch(in_ch, G_IO_OUT, guest_exec_input_watch, &gei->in);
}
if (has_output) {
#ifdef G_OS_WIN32
out_ch = g_io_channel_win32_new_fd(out_fd);
err_ch = g_io_channel_win32_new_fd(err_fd);
#else
out_ch = g_io_channel_unix_new(out_fd);
err_ch = g_io_channel_unix_new(err_fd);
#endif
g_io_channel_set_encoding(out_ch, NULL, NULL);
g_io_channel_set_encoding(err_ch, NULL, NULL);
g_io_channel_set_buffered(out_ch, false);
g_io_channel_set_buffered(err_ch, false);
g_io_channel_set_close_on_unref(out_ch, true);
g_io_channel_set_close_on_unref(err_ch, true);
g_io_add_watch(out_ch, G_IO_IN | G_IO_HUP,
guest_exec_output_watch, &gei->out);
g_io_add_watch(err_ch, G_IO_IN | G_IO_HUP,
guest_exec_output_watch, &gei->err);
}
done:
g_free(argv);
g_free(envp);
return ge;
}
/* Convert GuestFileWhence (either a raw integer or an enum value) into
* the guest's SEEK_ constants. */
int ga_parse_whence(GuestFileWhence *whence, Error **errp)
{
/*
* Exploit the fact that we picked values to match QGA_SEEK_*;
* however, we have to use a temporary variable since the union
* members may have different size.
*/
if (whence->type == QTYPE_QSTRING) {
int value = whence->u.name;
whence->type = QTYPE_QNUM;
whence->u.value = value;
}
switch (whence->u.value) {
case QGA_SEEK_SET:
return SEEK_SET;
case QGA_SEEK_CUR:
return SEEK_CUR;
case QGA_SEEK_END:
return SEEK_END;
}
error_setg(errp, "invalid whence code %"PRId64, whence->u.value);
return -1;
}
GuestHostName *qmp_guest_get_host_name(Error **errp)
{
GuestHostName *result = NULL;
g_autofree char *hostname = qemu_get_host_name(errp);
/*
* We want to avoid using g_get_host_name() because that
* caches the result and we wouldn't reflect changes in the
* host name.
*/
if (!hostname) {
hostname = g_strdup("localhost");
}
result = g_new0(GuestHostName, 1);
result->host_name = g_steal_pointer(&hostname);
return result;
}
GuestTimezone *qmp_guest_get_timezone(Error **errp)
{
GuestTimezone *info = NULL;
GTimeZone *tz = NULL;
gint64 now = 0;
gint32 intv = 0;
gchar const *name = NULL;
info = g_new0(GuestTimezone, 1);
tz = g_time_zone_new_local();
if (tz == NULL) {
error_setg(errp, QERR_QGA_COMMAND_FAILED,
"Couldn't retrieve local timezone");
goto error;
}
now = g_get_real_time() / G_USEC_PER_SEC;
intv = g_time_zone_find_interval(tz, G_TIME_TYPE_UNIVERSAL, now);
info->offset = g_time_zone_get_offset(tz, intv);
name = g_time_zone_get_abbreviation(tz, intv);
if (name != NULL) {
info->has_zone = true;
info->zone = g_strdup(name);
}
g_time_zone_unref(tz);
return info;
error:
g_free(info);
return NULL;
}
GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count,
int64_t count, Error **errp)
{
GuestFileHandle *gfh = guest_file_handle_find(handle, errp);
GuestFileRead *read_data;
if (!gfh) {
return NULL;
}
if (!has_count) {
count = QGA_READ_COUNT_DEFAULT;
} else if (count < 0 || count > GUEST_FILE_READ_COUNT_MAX) {
error_setg(errp, "value '%" PRId64 "' is invalid for argument count",
count);
return NULL;
}
read_data = guest_file_read_unsafe(gfh, count, errp);
if (!read_data) {
slog("guest-file-write failed, handle: %" PRId64, handle);
}
return read_data;
}
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