Import lpd, a re-implementation of the lpr daemon following the latest

OpenBSD coding practices (fork+exec/privsep/pledge/...).  It is only
intended to replace the lpd(8) daemon for the moment, not the lpr(1),
lprm(1), lpq(1) and lpc(8) commands.

This is a work in progress.  The server part should be fairly functionnal,
but the printer part is not complete: remote printers should work, for
local printers it depends on the setup.  Anyway, at this point it's better
in the tree than rotting on my disk.

ok deraadt@

1 files changed, 251 insertions, 0 deletions

diff --git a/usr.sbin/lpd/control.c b/usr.sbin/lpd/control.c
new file mode 100644
index 00000000000..325e21c25ba
--- /dev/null
+++ b/usr.sbin/lpd/control.c
@@ -0,0 +1,251 @@
+/*	$OpenBSD: control.c,v 1.1.1.1 2018/04/27 16:14:35 eric 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 <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 priviledges. */
+	if ((pw = getpwnam(LPD_USER)) == NULL)
+		fatalx("unknown user " LPD_USER);
+
+	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 (chroot(pw->pw_dir) == 1)
+		fatal("%s: chroot", __func__);
+
+	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);
+	}
+}