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|
/* $OpenBSD: control.c,v 1.3 2024/03/22 19:14:28 bluhm Exp $ */
/*
* Copyright (c) 2017 Eric Faurot <eric@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <event.h>
#include <imsg.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "lpd.h"
#include "log.h"
#include "proc.h"
#define CONTROL_BACKLOG 5
static void control_init(const char *);
static void control_listen(void);
static void control_pause(void);
static void control_resume(void);
static void control_accept(int, short, void *);
static void control_close(struct imsgproc *);
static void control_dispatch_priv(struct imsgproc *, struct imsg *, void *);
static void control_dispatch_client(struct imsgproc *, struct imsg *, void *);
static struct {
struct event evt;
int fd;
int pause;
} ctl;
void
control(int debug, int verbose)
{
struct passwd *pw;
/* Early initialisation. */
log_init(debug, LOG_DAEMON);
log_setverbose(verbose);
log_procinit("control");
setproctitle("control");
control_init(LPD_SOCKET);
/* Drop privileges. */
if ((pw = getpwnam(LPD_USER)) == NULL)
fatalx("unknown user " LPD_USER);
if (chroot(_PATH_VAREMPTY) == -1)
fatal("%s: chroot", __func__);
if (chdir("/") == -1)
fatal("%s: chdir", __func__);
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
fatal("cannot drop privileges");
if (pledge("stdio unix recvfd sendfd", NULL) == -1)
fatal("%s: pledge", __func__);
event_init();
signal(SIGPIPE, SIG_IGN);
/* Setup imsg socket with parent. */
p_priv = proc_attach(PROC_PRIV, 3);
if (p_priv == NULL)
fatal("%s: proc_attach", __func__);
proc_setcallback(p_priv, control_dispatch_priv, NULL);
proc_enable(p_priv);
event_dispatch();
exit(0);
}
static void
control_init(const char *path)
{
struct sockaddr_un sun;
mode_t old_umask;
int fd;
fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (fd == -1)
fatal("%s: socket", __func__);
memset(&sun, 0, sizeof(sun));
sun.sun_family = AF_UNIX;
strlcpy(sun.sun_path, LPD_SOCKET, sizeof(sun.sun_path));
if ((unlink(path) == -1) && (errno != ENOENT))
fatal("%s: unlink: %s", __func__, path);
old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1)
fatal("%s: bind: %s", __func__, path);
umask(old_umask);
if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1)
fatal("%s: chmod: %s", __func__, path);
ctl.fd = fd;
}
static void
control_listen(void)
{
if (listen(ctl.fd, CONTROL_BACKLOG) == -1)
fatal("%s: listen", __func__);
ctl.pause = 0;
control_resume();
}
static void
control_pause(void)
{
struct timeval tv;
event_del(&ctl.evt);
tv.tv_sec = 1;
tv.tv_usec = 0;
evtimer_set(&ctl.evt, control_accept, NULL);
evtimer_add(&ctl.evt, &tv);
ctl.pause = 1;
}
static void
control_resume(void)
{
if (ctl.pause) {
evtimer_del(&ctl.evt);
ctl.pause = 0;
}
event_set(&ctl.evt, ctl.fd, EV_READ | EV_PERSIST, control_accept, NULL);
event_add(&ctl.evt, NULL);
}
static void
control_accept(int fd, short event, void *arg)
{
struct imsgproc *proc;
int sock;
if (ctl.pause) {
ctl.pause = 0;
control_resume();
return;
}
sock = accept4(ctl.fd, NULL, NULL, SOCK_CLOEXEC | SOCK_NONBLOCK);
if (sock == -1) {
if (errno == ENFILE || errno == EMFILE)
control_pause();
else if (errno != EWOULDBLOCK && errno != EINTR &&
errno != ECONNABORTED)
log_warn("%s: accept4", __func__);
return;
}
proc = proc_attach(PROC_CLIENT, sock);
if (proc == NULL) {
log_warn("%s: proc_attach", __func__);
close(sock);
return;
}
proc_setcallback(proc, control_dispatch_client, NULL);
proc_enable(proc);
}
static void
control_close(struct imsgproc *proc)
{
proc_free(proc);
if (ctl.pause)
control_resume();
}
static void
control_dispatch_priv(struct imsgproc *proc, struct imsg *imsg, void *arg)
{
if (imsg == NULL) {
log_debug("%s: imsg connection lost", __func__);
event_loopexit(NULL);
return;
}
if (log_getverbose() > LOGLEVEL_IMSG)
log_imsg(proc, imsg);
switch (imsg->hdr.type) {
case IMSG_CONF_START:
m_end(proc);
break;
case IMSG_CONF_END:
m_end(proc);
control_listen();
break;
default:
fatalx("%s: unexpected imsg %s", __func__,
log_fmt_imsgtype(imsg->hdr.type));
}
}
static void
control_dispatch_client(struct imsgproc *proc, struct imsg *imsg, void *arg)
{
if (imsg == NULL) {
control_close(proc);
return;
}
if (log_getverbose() > LOGLEVEL_IMSG)
log_imsg(proc, imsg);
switch (imsg->hdr.type) {
default:
log_debug("%s: error handling imsg %d", __func__,
imsg->hdr.type);
}
}
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