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/*
* tlsdate-setter.c - privileged time setter for tlsdated
* Copyright (c) 2013 The Chromium 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 "config.h"
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <event2/event.h>
#include "src/conf.h"
#include "src/dbus.h"
#include "src/seccomp.h"
#include "src/tlsdate.h"
#include "src/util.h"
/* Atomically writes the timestamp to the specified fd. */
int
save_timestamp_to_fd (int fd, time_t t)
{
return platform->file_write(fd, &t, sizeof (t));
}
void
report_setter_error (siginfo_t *info)
{
const char *code;
int killit = 0;
switch (info->si_code)
{
case CLD_EXITED:
code = "EXITED";
break;
case CLD_KILLED:
code = "KILLED";
break;
case CLD_DUMPED:
code = "DUMPED";
break;
case CLD_STOPPED:
code = "STOPPED";
killit = 1;
break;
case CLD_TRAPPED:
code = "TRAPPED";
killit = 1;
break;
case CLD_CONTINUED:
code = "CONTINUED";
killit = 1;
break;
default:
code = "???";
killit = 1;
}
info ("tlsdate-setter exitting: code:%s status:%d pid:%d uid:%d",
code, info->si_status, info->si_pid, info->si_uid);
if (killit)
kill (info->si_pid, SIGKILL);
}
void
time_setter_coprocess (int time_fd, int notify_fd, struct state *state)
{
int save_fd = -1;
int status;
prctl (PR_SET_NAME, "tlsdated-setter");
if (state->opts.should_save_disk && !state->opts.dry_run)
{
const mode_t perms = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
/* TODO(wad) platform->file_open */
if ( (save_fd = open (state->timestamp_path,
O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC,
perms)) < 0 ||
fchmod (save_fd, perms) != 0)
{
/* Attempt to unlink the path on the way out. */
unlink (state->timestamp_path);
status = SETTER_NO_SAVE;
goto notify_and_die;
}
}
/* XXX: Drop all privs but CAP_SYS_TIME */
#ifdef HAVE_SECCOMP_FILTER
if (enable_setter_seccomp())
{
status = SETTER_NO_SBOX;
goto notify_and_die;
}
#endif
while (1)
{
struct timeval tv = { 0, 0 };
/* The wire protocol is a time_t, but the caller should
* always be the unprivileged tlsdated process which spawned this
* helper.
* There are two special messages:
* (time_t) 0: requests a clean shutdown
* (time_t) < 0: indicates not to write to disk
* On Linux, time_t is a signed long. Expanding the protocol
* is easy, but writing one long only is ideal.
*/
ssize_t bytes = read (time_fd, &tv.tv_sec, sizeof (tv.tv_sec));
int save = 1;
if (bytes == -1)
{
if (errno == EINTR)
continue;
status = SETTER_READ_ERR;
goto notify_and_die;
}
if (bytes == 0)
{
/* End of pipe */
status = SETTER_READ_ERR;
goto notify_and_die;
}
if (bytes != sizeof (tv.tv_sec))
continue;
if (tv.tv_sec < 0)
{
/* Don't write to disk */
tv.tv_sec = -tv.tv_sec;
save = 0;
}
if (tv.tv_sec == 0)
{
status = SETTER_EXIT;
goto notify_and_die;
}
if (is_sane_time (tv.tv_sec))
{
/* It would be nice if time was only allowed to move forward, but
* if a single time source is wrong, then it could make it impossible
* to recover from once the time is written to disk.
*/
status = SETTER_BAD_TIME;
if (!state->opts.dry_run)
{
if (settimeofday (&tv, NULL) < 0)
{
status = SETTER_SET_ERR;
goto notify_and_die;
}
if (state->opts.should_sync_hwclock &&
platform->rtc_write(&state->hwclock, &tv))
{
status = SETTER_NO_RTC;
goto notify_and_die;
}
if (save && save_fd != -1 &&
save_timestamp_to_fd (save_fd, tv.tv_sec))
{
status = SETTER_NO_SAVE;
goto notify_and_die;
}
}
status = SETTER_TIME_SET;
}
/* TODO(wad) platform->file_write */
IGNORE_EINTR (write (notify_fd, &status, sizeof(status)));
}
notify_and_die:
IGNORE_EINTR (write (notify_fd, &status, sizeof(status)));
close (notify_fd);
close (save_fd);
_exit (status);
}
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