1 /*
2  * Copyright (c) 2022 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/queue.h>
18 #include <sys/time.h>
19 #include <sys/types.h>
20 #include <sys/stat.h>
21 #include <sys/socket.h>
22 #include <sys/un.h>
23 #include <sys/wait.h>
24 
25 #include <fcntl.h>
26 #include <err.h>
27 #include <errno.h>
28 #include <event.h>
29 #include <limits.h>
30 #include <pwd.h>
31 #include <imsg.h>
32 #include <signal.h>
33 #include <siphash.h>
34 #include <stdarg.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <syslog.h>
39 #include <unistd.h>
40 
41 #include "got_error.h"
42 #include "got_opentemp.h"
43 #include "got_path.h"
44 #include "got_repository.h"
45 #include "got_object.h"
46 #include "got_reference.h"
47 
48 #include "got_lib_delta.h"
49 #include "got_lib_object.h"
50 #include "got_lib_object_cache.h"
51 #include "got_lib_hash.h"
52 #include "got_lib_gitproto.h"
53 #include "got_lib_pack.h"
54 #include "got_lib_repository.h"
55 
56 #include "gotd.h"
57 #include "log.h"
58 #include "listen.h"
59 #include "auth.h"
60 #include "session.h"
61 #include "repo_read.h"
62 #include "repo_write.h"
63 
64 #ifndef nitems
65 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
66 #endif
67 
68 enum gotd_client_state {
69 	GOTD_CLIENT_STATE_NEW,
70 	GOTD_CLIENT_STATE_ACCESS_GRANTED,
71 };
72 
73 struct gotd_client {
74 	STAILQ_ENTRY(gotd_client)	 entry;
75 	enum gotd_client_state		 state;
76 	uint32_t			 id;
77 	int				 fd;
78 	struct gotd_imsgev		 iev;
79 	struct event			 tmo;
80 	uid_t				 euid;
81 	gid_t				 egid;
82 	struct gotd_child_proc		*repo;
83 	struct gotd_child_proc		*auth;
84 	struct gotd_child_proc		*session;
85 	int				 required_auth;
86 };
87 STAILQ_HEAD(gotd_clients, gotd_client);
88 
89 static struct gotd_clients gotd_clients[GOTD_CLIENT_TABLE_SIZE];
90 static SIPHASH_KEY clients_hash_key;
91 volatile int client_cnt;
92 static struct timeval auth_timeout = { 5, 0 };
93 static struct gotd gotd;
94 
95 void gotd_sighdlr(int sig, short event, void *arg);
96 static void gotd_shutdown(void);
97 static const struct got_error *start_session_child(struct gotd_client *,
98     struct gotd_repo *, char *, const char *, int, int);
99 static const struct got_error *start_repo_child(struct gotd_client *,
100     enum gotd_procid, struct gotd_repo *, char *, const char *, int, int);
101 static const struct got_error *start_auth_child(struct gotd_client *, int,
102     struct gotd_repo *, char *, const char *, int, int);
103 static void kill_proc(struct gotd_child_proc *, int);
104 
105 __dead static void
106 usage(void)
107 {
108 	fprintf(stderr, "usage: %s [-dnv] [-f config-file]\n", getprogname());
109 	exit(1);
110 }
111 
112 static int
113 unix_socket_listen(const char *unix_socket_path, uid_t uid, gid_t gid)
114 {
115 	struct sockaddr_un sun;
116 	int fd = -1;
117 	mode_t old_umask, mode;
118 
119 	fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
120 	if (fd == -1) {
121 		log_warn("socket");
122 		return -1;
123 	}
124 
125 	sun.sun_family = AF_UNIX;
126 	if (strlcpy(sun.sun_path, unix_socket_path,
127 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
128 		log_warnx("%s: name too long", unix_socket_path);
129 		close(fd);
130 		return -1;
131 	}
132 
133 	if (unlink(unix_socket_path) == -1) {
134 		if (errno != ENOENT) {
135 			log_warn("unlink %s", unix_socket_path);
136 			close(fd);
137 			return -1;
138 		}
139 	}
140 
141 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
142 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
143 
144 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
145 		log_warn("bind: %s", unix_socket_path);
146 		close(fd);
147 		umask(old_umask);
148 		return -1;
149 	}
150 
151 	umask(old_umask);
152 
153 	if (chmod(unix_socket_path, mode) == -1) {
154 		log_warn("chmod %o %s", mode, unix_socket_path);
155 		close(fd);
156 		unlink(unix_socket_path);
157 		return -1;
158 	}
159 
160 	if (chown(unix_socket_path, uid, gid) == -1) {
161 		log_warn("chown %s uid=%d gid=%d", unix_socket_path, uid, gid);
162 		close(fd);
163 		unlink(unix_socket_path);
164 		return -1;
165 	}
166 
167 	if (listen(fd, GOTD_UNIX_SOCKET_BACKLOG) == -1) {
168 		log_warn("listen");
169 		close(fd);
170 		unlink(unix_socket_path);
171 		return -1;
172 	}
173 
174 	return fd;
175 }
176 
177 static uint64_t
178 client_hash(uint32_t client_id)
179 {
180 	return SipHash24(&clients_hash_key, &client_id, sizeof(client_id));
181 }
182 
183 static void
184 add_client(struct gotd_client *client)
185 {
186 	uint64_t slot = client_hash(client->id) % nitems(gotd_clients);
187 	STAILQ_INSERT_HEAD(&gotd_clients[slot], client, entry);
188 	client_cnt++;
189 }
190 
191 static struct gotd_client *
192 find_client(uint32_t client_id)
193 {
194 	uint64_t slot;
195 	struct gotd_client *c;
196 
197 	slot = client_hash(client_id) % nitems(gotd_clients);
198 	STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
199 		if (c->id == client_id)
200 			return c;
201 	}
202 
203 	return NULL;
204 }
205 
206 static struct gotd_client *
207 find_client_by_proc_fd(int fd)
208 {
209 	uint64_t slot;
210 
211 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
212 		struct gotd_client *c;
213 
214 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
215 			if (c->repo && c->repo->iev.ibuf.fd == fd)
216 				return c;
217 			if (c->auth && c->auth->iev.ibuf.fd == fd)
218 				return c;
219 			if (c->session && c->session->iev.ibuf.fd == fd)
220 				return c;
221 		}
222 	}
223 
224 	return NULL;
225 }
226 
227 static int
228 client_is_reading(struct gotd_client *client)
229 {
230 	return (client->required_auth &
231 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) == GOTD_AUTH_READ;
232 }
233 
234 static int
235 client_is_writing(struct gotd_client *client)
236 {
237 	return (client->required_auth &
238 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) ==
239 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE);
240 }
241 
242 static const struct got_error *
243 ensure_client_is_not_writing(struct gotd_client *client)
244 {
245 	if (client_is_writing(client)) {
246 		return got_error_fmt(GOT_ERR_BAD_PACKET,
247 		    "uid %d made a read-request but is writing to "
248 		    "a repository", client->euid);
249 	}
250 
251 	return NULL;
252 }
253 
254 static const struct got_error *
255 ensure_client_is_not_reading(struct gotd_client *client)
256 {
257 	if (client_is_reading(client)) {
258 		return got_error_fmt(GOT_ERR_BAD_PACKET,
259 		    "uid %d made a write-request but is reading from "
260 		    "a repository", client->euid);
261 	}
262 
263 	return NULL;
264 }
265 
266 static void
267 wait_for_child(pid_t child_pid)
268 {
269 	pid_t pid;
270 	int status;
271 
272 	log_debug("waiting for child PID %ld to terminate",
273 	    (long)child_pid);
274 
275 	do {
276 		pid = waitpid(child_pid, &status, WNOHANG);
277 		if (pid == -1) {
278 			if (errno != EINTR && errno != ECHILD)
279 				fatal("wait");
280 		} else if (WIFSIGNALED(status)) {
281 			log_warnx("child PID %ld terminated; signal %d",
282 			    (long)pid, WTERMSIG(status));
283 		}
284 	} while (pid != -1 || (pid == -1 && errno == EINTR));
285 }
286 
287 static void
288 proc_done(struct gotd_child_proc *proc)
289 {
290 	event_del(&proc->iev.ev);
291 	msgbuf_clear(&proc->iev.ibuf.w);
292 	close(proc->iev.ibuf.fd);
293 	kill_proc(proc, 0);
294 	wait_for_child(proc->pid);
295 	free(proc);
296 }
297 
298 static void
299 kill_auth_proc(struct gotd_client *client)
300 {
301 	struct gotd_child_proc *proc;
302 
303 	if (client->auth == NULL)
304 		return;
305 
306 	proc = client->auth;
307 	client->auth = NULL;
308 
309 	proc_done(proc);
310 }
311 
312 static void
313 kill_session_proc(struct gotd_client *client)
314 {
315 	struct gotd_child_proc *proc;
316 
317 	if (client->session == NULL)
318 		return;
319 
320 	proc = client->session;
321 	client->session = NULL;
322 
323 	proc_done(proc);
324 }
325 
326 static void
327 disconnect(struct gotd_client *client)
328 {
329 	struct gotd_imsg_disconnect idisconnect;
330 	struct gotd_child_proc *proc = client->repo;
331 	struct gotd_child_proc *listen_proc = &gotd.listen_proc;
332 	uint64_t slot;
333 
334 	log_debug("uid %d: disconnecting", client->euid);
335 
336 	kill_auth_proc(client);
337 	kill_session_proc(client);
338 
339 	if (proc) {
340 		event_del(&proc->iev.ev);
341 		msgbuf_clear(&proc->iev.ibuf.w);
342 		close(proc->iev.ibuf.fd);
343 		kill_proc(proc, 0);
344 		wait_for_child(proc->pid);
345 		free(proc);
346 		proc = NULL;
347 	}
348 
349 	idisconnect.client_id = client->id;
350 	if (gotd_imsg_compose_event(&listen_proc->iev,
351 	    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
352 	    &idisconnect, sizeof(idisconnect)) == -1)
353 		log_warn("imsg compose DISCONNECT");
354 
355 	slot = client_hash(client->id) % nitems(gotd_clients);
356 	STAILQ_REMOVE(&gotd_clients[slot], client, gotd_client, entry);
357 	imsg_clear(&client->iev.ibuf);
358 	event_del(&client->iev.ev);
359 	evtimer_del(&client->tmo);
360 	if (client->fd != -1)
361 		close(client->fd);
362 	else if (client->iev.ibuf.fd != -1)
363 		close(client->iev.ibuf.fd);
364 	free(client);
365 	client_cnt--;
366 }
367 
368 static void
369 disconnect_on_error(struct gotd_client *client, const struct got_error *err)
370 {
371 	struct imsgbuf ibuf;
372 
373 	log_warnx("uid %d: %s", client->euid, err->msg);
374 	if (err->code != GOT_ERR_EOF && client->fd != -1) {
375 		imsg_init(&ibuf, client->fd);
376 		gotd_imsg_send_error(&ibuf, 0, PROC_GOTD, err);
377 		imsg_clear(&ibuf);
378 	}
379 	disconnect(client);
380 }
381 
382 static const struct got_error *
383 send_repo_info(struct gotd_imsgev *iev, struct gotd_repo *repo)
384 {
385 	const struct got_error *err = NULL;
386 	struct gotd_imsg_info_repo irepo;
387 
388 	memset(&irepo, 0, sizeof(irepo));
389 
390 	if (strlcpy(irepo.repo_name, repo->name, sizeof(irepo.repo_name))
391 	    >= sizeof(irepo.repo_name))
392 		return got_error_msg(GOT_ERR_NO_SPACE, "repo name too long");
393 	if (strlcpy(irepo.repo_path, repo->path, sizeof(irepo.repo_path))
394 	    >= sizeof(irepo.repo_path))
395 		return got_error_msg(GOT_ERR_NO_SPACE, "repo path too long");
396 
397 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_REPO, PROC_GOTD, -1,
398 	    &irepo, sizeof(irepo)) == -1) {
399 		err = got_error_from_errno("imsg compose INFO_REPO");
400 		if (err)
401 			return err;
402 	}
403 
404 	return NULL;
405 }
406 
407 static const struct got_error *
408 send_client_info(struct gotd_imsgev *iev, struct gotd_client *client)
409 {
410 	const struct got_error *err = NULL;
411 	struct gotd_imsg_info_client iclient;
412 	struct gotd_child_proc *proc;
413 
414 	memset(&iclient, 0, sizeof(iclient));
415 	iclient.euid = client->euid;
416 	iclient.egid = client->egid;
417 
418 	proc = client->repo;
419 	if (proc) {
420 		if (strlcpy(iclient.repo_name, proc->repo_path,
421 		    sizeof(iclient.repo_name)) >= sizeof(iclient.repo_name)) {
422 			return got_error_msg(GOT_ERR_NO_SPACE,
423 			    "repo name too long");
424 		}
425 		if (client_is_writing(client))
426 			iclient.is_writing = 1;
427 
428 		iclient.repo_child_pid = proc->pid;
429 	}
430 
431 	if (client->session)
432 		iclient.session_child_pid = client->session->pid;
433 
434 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_CLIENT, PROC_GOTD, -1,
435 	    &iclient, sizeof(iclient)) == -1) {
436 		err = got_error_from_errno("imsg compose INFO_CLIENT");
437 		if (err)
438 			return err;
439 	}
440 
441 	return NULL;
442 }
443 
444 static const struct got_error *
445 send_info(struct gotd_client *client)
446 {
447 	const struct got_error *err = NULL;
448 	struct gotd_imsg_info info;
449 	uint64_t slot;
450 	struct gotd_repo *repo;
451 
452 	if (client->euid != 0)
453 		return got_error_set_errno(EPERM, "info");
454 
455 	info.pid = gotd.pid;
456 	info.verbosity = gotd.verbosity;
457 	info.nrepos = gotd.nrepos;
458 	info.nclients = client_cnt - 1;
459 
460 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_INFO, PROC_GOTD, -1,
461 	    &info, sizeof(info)) == -1) {
462 		err = got_error_from_errno("imsg compose INFO");
463 		if (err)
464 			return err;
465 	}
466 
467 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
468 		err = send_repo_info(&client->iev, repo);
469 		if (err)
470 			return err;
471 	}
472 
473 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
474 		struct gotd_client *c;
475 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
476 			if (c->id == client->id)
477 				continue;
478 			err = send_client_info(&client->iev, c);
479 			if (err)
480 				return err;
481 		}
482 	}
483 
484 	return NULL;
485 }
486 
487 static const struct got_error *
488 stop_gotd(struct gotd_client *client)
489 {
490 
491 	if (client->euid != 0)
492 		return got_error_set_errno(EPERM, "stop");
493 
494 	gotd_shutdown();
495 	/* NOTREACHED */
496 	return NULL;
497 }
498 
499 static const struct got_error *
500 start_client_authentication(struct gotd_client *client, struct imsg *imsg)
501 {
502 	const struct got_error *err;
503 	struct gotd_imsg_list_refs ireq;
504 	struct gotd_repo *repo = NULL;
505 	size_t datalen;
506 
507 	log_debug("list-refs request from uid %d", client->euid);
508 
509 	if (client->state != GOTD_CLIENT_STATE_NEW)
510 		return got_error_msg(GOT_ERR_BAD_REQUEST,
511 		    "unexpected list-refs request received");
512 
513 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
514 	if (datalen != sizeof(ireq))
515 		return got_error(GOT_ERR_PRIVSEP_LEN);
516 
517 	memcpy(&ireq, imsg->data, datalen);
518 
519 	if (ireq.client_is_reading) {
520 		err = ensure_client_is_not_writing(client);
521 		if (err)
522 			return err;
523 		repo = gotd_find_repo_by_name(ireq.repo_name, &gotd);
524 		if (repo == NULL)
525 			return got_error(GOT_ERR_NOT_GIT_REPO);
526 		err = start_auth_child(client, GOTD_AUTH_READ, repo,
527 		    gotd.argv0, gotd.confpath, gotd.daemonize,
528 		    gotd.verbosity);
529 		if (err)
530 			return err;
531 	} else {
532 		err = ensure_client_is_not_reading(client);
533 		if (err)
534 			return err;
535 		repo = gotd_find_repo_by_name(ireq.repo_name, &gotd);
536 		if (repo == NULL)
537 			return got_error(GOT_ERR_NOT_GIT_REPO);
538 		err = start_auth_child(client,
539 		    GOTD_AUTH_READ | GOTD_AUTH_WRITE,
540 		    repo, gotd.argv0, gotd.confpath, gotd.daemonize,
541 		    gotd.verbosity);
542 		if (err)
543 			return err;
544 	}
545 
546 	evtimer_add(&client->tmo, &auth_timeout);
547 
548 	/* Flow continues upon authentication successs/failure or timeout. */
549 	return NULL;
550 }
551 
552 static void
553 gotd_request(int fd, short events, void *arg)
554 {
555 	struct gotd_imsgev *iev = arg;
556 	struct imsgbuf *ibuf = &iev->ibuf;
557 	struct gotd_client *client = iev->handler_arg;
558 	const struct got_error *err = NULL;
559 	struct imsg imsg;
560 	ssize_t n;
561 
562 	if (events & EV_WRITE) {
563 		while (ibuf->w.queued) {
564 			n = msgbuf_write(&ibuf->w);
565 			if (n == -1 && errno == EPIPE) {
566 				/*
567 				 * The client has closed its socket.
568 				 * This can happen when Git clients are
569 				 * done sending pack file data.
570 				 */
571 				msgbuf_clear(&ibuf->w);
572 				continue;
573 			} else if (n == -1 && errno != EAGAIN) {
574 				err = got_error_from_errno("imsg_flush");
575 				disconnect_on_error(client, err);
576 				return;
577 			}
578 			if (n == 0) {
579 				/* Connection closed. */
580 				err = got_error(GOT_ERR_EOF);
581 				disconnect_on_error(client, err);
582 				return;
583 			}
584 		}
585 
586 		/* Disconnect gotctl(8) now that messages have been sent. */
587 		if (!client_is_reading(client) && !client_is_writing(client)) {
588 			disconnect(client);
589 			return;
590 		}
591 	}
592 
593 	if ((events & EV_READ) == 0)
594 		return;
595 
596 	memset(&imsg, 0, sizeof(imsg));
597 
598 	while (err == NULL) {
599 		err = gotd_imsg_recv(&imsg, ibuf, 0);
600 		if (err) {
601 			if (err->code == GOT_ERR_PRIVSEP_READ)
602 				err = NULL;
603 			break;
604 		}
605 
606 		evtimer_del(&client->tmo);
607 
608 		switch (imsg.hdr.type) {
609 		case GOTD_IMSG_INFO:
610 			err = send_info(client);
611 			break;
612 		case GOTD_IMSG_STOP:
613 			err = stop_gotd(client);
614 			break;
615 		case GOTD_IMSG_LIST_REFS:
616 			err = start_client_authentication(client, &imsg);
617 			break;
618 		default:
619 			log_debug("unexpected imsg %d", imsg.hdr.type);
620 			err = got_error(GOT_ERR_PRIVSEP_MSG);
621 			break;
622 		}
623 
624 		imsg_free(&imsg);
625 	}
626 
627 	if (err) {
628 		disconnect_on_error(client, err);
629 	} else {
630 		gotd_imsg_event_add(&client->iev);
631 	}
632 }
633 
634 static void
635 gotd_auth_timeout(int fd, short events, void *arg)
636 {
637 	struct gotd_client *client = arg;
638 
639 	log_debug("disconnecting uid %d due to authentication timeout",
640 	    client->euid);
641 	disconnect(client);
642 }
643 
644 static const struct got_error *
645 recv_connect(uint32_t *client_id, struct imsg *imsg)
646 {
647 	const struct got_error *err = NULL;
648 	struct gotd_imsg_connect iconnect;
649 	size_t datalen;
650 	int s = -1;
651 	struct gotd_client *client = NULL;
652 
653 	*client_id = 0;
654 
655 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
656 	if (datalen != sizeof(iconnect))
657 		return got_error(GOT_ERR_PRIVSEP_LEN);
658 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
659 
660 	s = imsg->fd;
661 	if (s == -1) {
662 		err = got_error(GOT_ERR_PRIVSEP_NO_FD);
663 		goto done;
664 	}
665 
666 	if (find_client(iconnect.client_id)) {
667 		err = got_error_msg(GOT_ERR_CLIENT_ID, "duplicate client ID");
668 		goto done;
669 	}
670 
671 	client = calloc(1, sizeof(*client));
672 	if (client == NULL) {
673 		err = got_error_from_errno("calloc");
674 		goto done;
675 	}
676 
677 	*client_id = iconnect.client_id;
678 
679 	client->state = GOTD_CLIENT_STATE_NEW;
680 	client->id = iconnect.client_id;
681 	client->fd = s;
682 	s = -1;
683 	/* The auth process will verify UID/GID for us. */
684 	client->euid = iconnect.euid;
685 	client->egid = iconnect.egid;
686 
687 	imsg_init(&client->iev.ibuf, client->fd);
688 	client->iev.handler = gotd_request;
689 	client->iev.events = EV_READ;
690 	client->iev.handler_arg = client;
691 
692 	event_set(&client->iev.ev, client->fd, EV_READ, gotd_request,
693 	    &client->iev);
694 	gotd_imsg_event_add(&client->iev);
695 
696 	evtimer_set(&client->tmo, gotd_auth_timeout, client);
697 
698 	add_client(client);
699 	log_debug("%s: new client uid %d connected on fd %d", __func__,
700 	    client->euid, client->fd);
701 done:
702 	if (err) {
703 		struct gotd_child_proc *listen_proc = &gotd.listen_proc;
704 		struct gotd_imsg_disconnect idisconnect;
705 
706 		idisconnect.client_id = client->id;
707 		if (gotd_imsg_compose_event(&listen_proc->iev,
708 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
709 		    &idisconnect, sizeof(idisconnect)) == -1)
710 			log_warn("imsg compose DISCONNECT");
711 
712 		if (s != -1)
713 			close(s);
714 	}
715 
716 	return err;
717 }
718 
719 static const char *gotd_proc_names[PROC_MAX] = {
720 	"parent",
721 	"listen",
722 	"auth",
723 	"session",
724 	"repo_read",
725 	"repo_write"
726 };
727 
728 static void
729 kill_proc(struct gotd_child_proc *proc, int fatal)
730 {
731 	if (fatal) {
732 		log_warnx("sending SIGKILL to PID %d", proc->pid);
733 		kill(proc->pid, SIGKILL);
734 	} else
735 		kill(proc->pid, SIGTERM);
736 }
737 
738 static void
739 gotd_shutdown(void)
740 {
741 	struct gotd_child_proc *proc;
742 	uint64_t slot;
743 
744 	log_debug("shutting down");
745 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
746 		struct gotd_client *c, *tmp;
747 
748 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
749 			disconnect(c);
750 	}
751 
752 	proc = &gotd.listen_proc;
753 	msgbuf_clear(&proc->iev.ibuf.w);
754 	close(proc->iev.ibuf.fd);
755 	kill_proc(proc, 0);
756 	wait_for_child(proc->pid);
757 
758 	log_info("terminating");
759 	exit(0);
760 }
761 
762 void
763 gotd_sighdlr(int sig, short event, void *arg)
764 {
765 	/*
766 	 * Normal signal handler rules don't apply because libevent
767 	 * decouples for us.
768 	 */
769 
770 	switch (sig) {
771 	case SIGHUP:
772 		log_info("%s: ignoring SIGHUP", __func__);
773 		break;
774 	case SIGUSR1:
775 		log_info("%s: ignoring SIGUSR1", __func__);
776 		break;
777 	case SIGTERM:
778 	case SIGINT:
779 		gotd_shutdown();
780 		break;
781 	default:
782 		fatalx("unexpected signal");
783 	}
784 }
785 
786 static const struct got_error *
787 ensure_proc_is_reading(struct gotd_client *client,
788     struct gotd_child_proc *proc)
789 {
790 	if (!client_is_reading(client)) {
791 		kill_proc(proc, 1);
792 		return got_error_fmt(GOT_ERR_BAD_PACKET,
793 		    "PID %d handled a read-request for uid %d but this "
794 		    "user is not reading from a repository", proc->pid,
795 		    client->euid);
796 	}
797 
798 	return NULL;
799 }
800 
801 static const struct got_error *
802 ensure_proc_is_writing(struct gotd_client *client,
803     struct gotd_child_proc *proc)
804 {
805 	if (!client_is_writing(client)) {
806 		kill_proc(proc, 1);
807 		return got_error_fmt(GOT_ERR_BAD_PACKET,
808 		    "PID %d handled a write-request for uid %d but this "
809 		    "user is not writing to a repository", proc->pid,
810 		    client->euid);
811 	}
812 
813 	return NULL;
814 }
815 
816 static int
817 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
818     struct imsg *imsg)
819 {
820 	const struct got_error *err;
821 	int ret = 0;
822 
823 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
824 		if (client->repo == NULL)
825 			fatalx("no process found for uid %d", client->euid);
826 		if (proc->pid != client->repo->pid) {
827 			kill_proc(proc, 1);
828 			log_warnx("received message from PID %d for uid %d, "
829 			    "while PID %d is the process serving this user",
830 			    proc->pid, client->euid, client->repo->pid);
831 			return 0;
832 		}
833 	}
834 	if (proc->type == PROC_SESSION) {
835 		if (client->session == NULL) {
836 			log_warnx("no session found for uid %d", client->euid);
837 			return 0;
838 		}
839 		if (proc->pid != client->session->pid) {
840 			kill_proc(proc, 1);
841 			log_warnx("received message from PID %d for uid %d, "
842 			    "while PID %d is the process serving this user",
843 			    proc->pid, client->euid, client->session->pid);
844 			return 0;
845 		}
846 	}
847 
848 	switch (imsg->hdr.type) {
849 	case GOTD_IMSG_ERROR:
850 		ret = 1;
851 		break;
852 	case GOTD_IMSG_CONNECT:
853 		if (proc->type != PROC_LISTEN) {
854 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
855 			    "new connection for uid %d from PID %d "
856 			    "which is not the listen process",
857 			    proc->pid, client->euid);
858 		} else
859 			ret = 1;
860 		break;
861 	case GOTD_IMSG_ACCESS_GRANTED:
862 		if (proc->type != PROC_AUTH) {
863 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
864 			    "authentication of uid %d from PID %d "
865 			    "which is not the auth process",
866 			    proc->pid, client->euid);
867 		} else
868 			ret = 1;
869 		break;
870 	case GOTD_IMSG_CLIENT_SESSION_READY:
871 		if (proc->type != PROC_SESSION) {
872 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
873 			    "unexpected \"ready\" signal from PID %d",
874 			    proc->pid);
875 		} else
876 			ret = 1;
877 		break;
878 	case GOTD_IMSG_REPO_CHILD_READY:
879 		if (proc->type != PROC_REPO_READ &&
880 		    proc->type != PROC_REPO_WRITE) {
881 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
882 			    "unexpected \"ready\" signal from PID %d",
883 			    proc->pid);
884 		} else
885 			ret = 1;
886 		break;
887 	case GOTD_IMSG_PACKFILE_DONE:
888 		err = ensure_proc_is_reading(client, proc);
889 		if (err)
890 			log_warnx("uid %d: %s", client->euid, err->msg);
891 		else
892 			ret = 1;
893 		break;
894 	case GOTD_IMSG_PACKFILE_INSTALL:
895 	case GOTD_IMSG_REF_UPDATES_START:
896 	case GOTD_IMSG_REF_UPDATE:
897 		err = ensure_proc_is_writing(client, proc);
898 		if (err)
899 			log_warnx("uid %d: %s", client->euid, err->msg);
900 		else
901 			ret = 1;
902 		break;
903 	default:
904 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
905 		break;
906 	}
907 
908 	return ret;
909 }
910 
911 static const struct got_error *
912 connect_repo_child(struct gotd_client *client,
913     struct gotd_child_proc *repo_proc)
914 {
915 	static const struct got_error *err;
916 	struct gotd_imsgev *session_iev = &client->session->iev;
917 	struct gotd_imsg_connect_repo_child ireq;
918 	int pipe[2];
919 
920 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
921 		return got_error_msg(GOT_ERR_BAD_REQUEST,
922 		    "unexpected repo child ready signal received");
923 
924 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
925 	    PF_UNSPEC, pipe) == -1)
926 		fatal("socketpair");
927 
928 	memset(&ireq, 0, sizeof(ireq));
929 	ireq.client_id = client->id;
930 	ireq.proc_id = repo_proc->type;
931 
932 	/* Pass repo child pipe to session child process. */
933 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
934 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
935 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
936 		close(pipe[0]);
937 		close(pipe[1]);
938 		return err;
939 	}
940 
941 	/* Pass session child pipe to repo child process. */
942 	if (gotd_imsg_compose_event(&repo_proc->iev,
943 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
944 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
945 		close(pipe[1]);
946 		return err;
947 	}
948 
949 	return NULL;
950 }
951 
952 static void
953 gotd_dispatch_listener(int fd, short event, void *arg)
954 {
955 	struct gotd_imsgev *iev = arg;
956 	struct imsgbuf *ibuf = &iev->ibuf;
957 	struct gotd_child_proc *proc = &gotd.listen_proc;
958 	ssize_t n;
959 	int shut = 0;
960 	struct imsg imsg;
961 
962 	if (proc->iev.ibuf.fd != fd)
963 		fatalx("%s: unexpected fd %d", __func__, fd);
964 
965 	if (event & EV_READ) {
966 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
967 			fatal("imsg_read error");
968 		if (n == 0) {
969 			/* Connection closed. */
970 			shut = 1;
971 			goto done;
972 		}
973 	}
974 
975 	if (event & EV_WRITE) {
976 		n = msgbuf_write(&ibuf->w);
977 		if (n == -1 && errno != EAGAIN)
978 			fatal("msgbuf_write");
979 		if (n == 0) {
980 			/* Connection closed. */
981 			shut = 1;
982 			goto done;
983 		}
984 	}
985 
986 	for (;;) {
987 		const struct got_error *err = NULL;
988 		struct gotd_client *client = NULL;
989 		uint32_t client_id = 0;
990 		int do_disconnect = 0;
991 
992 		if ((n = imsg_get(ibuf, &imsg)) == -1)
993 			fatal("%s: imsg_get error", __func__);
994 		if (n == 0)	/* No more messages. */
995 			break;
996 
997 		switch (imsg.hdr.type) {
998 		case GOTD_IMSG_ERROR:
999 			do_disconnect = 1;
1000 			err = gotd_imsg_recv_error(&client_id, &imsg);
1001 			break;
1002 		case GOTD_IMSG_CONNECT:
1003 			err = recv_connect(&client_id, &imsg);
1004 			break;
1005 		default:
1006 			log_debug("unexpected imsg %d", imsg.hdr.type);
1007 			break;
1008 		}
1009 
1010 		client = find_client(client_id);
1011 		if (client == NULL) {
1012 			log_warnx("%s: client not found", __func__);
1013 			imsg_free(&imsg);
1014 			continue;
1015 		}
1016 
1017 		if (err)
1018 			log_warnx("uid %d: %s", client->euid, err->msg);
1019 
1020 		if (do_disconnect) {
1021 			if (err)
1022 				disconnect_on_error(client, err);
1023 			else
1024 				disconnect(client);
1025 		}
1026 
1027 		imsg_free(&imsg);
1028 	}
1029 done:
1030 	if (!shut) {
1031 		gotd_imsg_event_add(iev);
1032 	} else {
1033 		/* This pipe is dead. Remove its event handler */
1034 		event_del(&iev->ev);
1035 		event_loopexit(NULL);
1036 	}
1037 }
1038 
1039 static void
1040 gotd_dispatch_auth_child(int fd, short event, void *arg)
1041 {
1042 	const struct got_error *err = NULL;
1043 	struct gotd_imsgev *iev = arg;
1044 	struct imsgbuf *ibuf = &iev->ibuf;
1045 	struct gotd_client *client;
1046 	struct gotd_repo *repo = NULL;
1047 	ssize_t n;
1048 	int shut = 0;
1049 	struct imsg imsg;
1050 	uint32_t client_id = 0;
1051 	int do_disconnect = 0;
1052 
1053 	client = find_client_by_proc_fd(fd);
1054 	if (client == NULL) {
1055 		/* Can happen during process teardown. */
1056 		warnx("cannot find client for fd %d", fd);
1057 		shut = 1;
1058 		goto done;
1059 	}
1060 
1061 	if (client->auth == NULL)
1062 		fatalx("cannot find auth child process for fd %d", fd);
1063 
1064 	if (event & EV_READ) {
1065 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1066 			fatal("imsg_read error");
1067 		if (n == 0) {
1068 			/* Connection closed. */
1069 			shut = 1;
1070 			goto done;
1071 		}
1072 	}
1073 
1074 	if (event & EV_WRITE) {
1075 		n = msgbuf_write(&ibuf->w);
1076 		if (n == -1 && errno != EAGAIN)
1077 			fatal("msgbuf_write");
1078 		if (n == 0) {
1079 			/* Connection closed. */
1080 			shut = 1;
1081 		}
1082 		goto done;
1083 	}
1084 
1085 	if (client->auth->iev.ibuf.fd != fd)
1086 		fatalx("%s: unexpected fd %d", __func__, fd);
1087 
1088 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1089 		fatal("%s: imsg_get error", __func__);
1090 	if (n == 0)	/* No more messages. */
1091 		return;
1092 
1093 	evtimer_del(&client->tmo);
1094 
1095 	switch (imsg.hdr.type) {
1096 	case GOTD_IMSG_ERROR:
1097 		do_disconnect = 1;
1098 		err = gotd_imsg_recv_error(&client_id, &imsg);
1099 		break;
1100 	case GOTD_IMSG_ACCESS_GRANTED:
1101 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1102 		break;
1103 	default:
1104 		do_disconnect = 1;
1105 		log_debug("unexpected imsg %d", imsg.hdr.type);
1106 		break;
1107 	}
1108 
1109 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1110 		do_disconnect = 1;
1111 		log_debug("dropping imsg type %d from PID %d",
1112 		    imsg.hdr.type, client->auth->pid);
1113 	}
1114 	imsg_free(&imsg);
1115 
1116 	if (do_disconnect) {
1117 		if (err)
1118 			disconnect_on_error(client, err);
1119 		else
1120 			disconnect(client);
1121 		goto done;
1122 	}
1123 
1124 	repo = gotd_find_repo_by_name(client->auth->repo_name, &gotd);
1125 	if (repo == NULL) {
1126 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1127 		goto done;
1128 	}
1129 	kill_auth_proc(client);
1130 
1131 	log_info("authenticated uid %d for repository %s",
1132 	    client->euid, repo->name);
1133 
1134 	err = start_session_child(client, repo, gotd.argv0,
1135 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1136 	if (err)
1137 		goto done;
1138 done:
1139 	if (err)
1140 		log_warnx("uid %d: %s", client->euid, err->msg);
1141 
1142 	/* We might have killed the auth process by now. */
1143 	if (client->auth != NULL) {
1144 		if (!shut) {
1145 			gotd_imsg_event_add(iev);
1146 		} else {
1147 			/* This pipe is dead. Remove its event handler */
1148 			event_del(&iev->ev);
1149 		}
1150 	}
1151 }
1152 
1153 static const struct got_error *
1154 connect_session(struct gotd_client *client)
1155 {
1156 	const struct got_error *err = NULL;
1157 	struct gotd_imsg_connect iconnect;
1158 	int s;
1159 
1160 	memset(&iconnect, 0, sizeof(iconnect));
1161 
1162 	s = dup(client->fd);
1163 	if (s == -1)
1164 		return got_error_from_errno("dup");
1165 
1166 	iconnect.client_id = client->id;
1167 	iconnect.euid = client->euid;
1168 	iconnect.egid = client->egid;
1169 
1170 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1171 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1172 		err = got_error_from_errno("imsg compose CONNECT");
1173 		close(s);
1174 		return err;
1175 	}
1176 
1177 	/*
1178 	 * We are no longer interested in messages from this client.
1179 	 * Further client requests will be handled by the session process.
1180 	 */
1181 	msgbuf_clear(&client->iev.ibuf.w);
1182 	imsg_clear(&client->iev.ibuf);
1183 	event_del(&client->iev.ev);
1184 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1185 
1186 	return NULL;
1187 }
1188 
1189 static void
1190 gotd_dispatch_client_session(int fd, short event, void *arg)
1191 {
1192 	struct gotd_imsgev *iev = arg;
1193 	struct imsgbuf *ibuf = &iev->ibuf;
1194 	struct gotd_child_proc *proc = NULL;
1195 	struct gotd_client *client = NULL;
1196 	ssize_t n;
1197 	int shut = 0;
1198 	struct imsg imsg;
1199 
1200 	client = find_client_by_proc_fd(fd);
1201 	if (client == NULL) {
1202 		/* Can happen during process teardown. */
1203 		warnx("cannot find client for fd %d", fd);
1204 		shut = 1;
1205 		goto done;
1206 	}
1207 
1208 	if (event & EV_READ) {
1209 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1210 			fatal("imsg_read error");
1211 		if (n == 0) {
1212 			/* Connection closed. */
1213 			shut = 1;
1214 			goto done;
1215 		}
1216 	}
1217 
1218 	if (event & EV_WRITE) {
1219 		n = msgbuf_write(&ibuf->w);
1220 		if (n == -1 && errno != EAGAIN)
1221 			fatal("msgbuf_write");
1222 		if (n == 0) {
1223 			/* Connection closed. */
1224 			shut = 1;
1225 			goto done;
1226 		}
1227 	}
1228 
1229 	proc = client->session;
1230 	if (proc == NULL)
1231 		fatalx("cannot find session child process for fd %d", fd);
1232 
1233 	for (;;) {
1234 		const struct got_error *err = NULL;
1235 		uint32_t client_id = 0;
1236 		int do_disconnect = 0, do_start_repo_child = 0;
1237 
1238 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1239 			fatal("%s: imsg_get error", __func__);
1240 		if (n == 0)	/* No more messages. */
1241 			break;
1242 
1243 		switch (imsg.hdr.type) {
1244 		case GOTD_IMSG_ERROR:
1245 			do_disconnect = 1;
1246 			err = gotd_imsg_recv_error(&client_id, &imsg);
1247 			break;
1248 		case GOTD_IMSG_CLIENT_SESSION_READY:
1249 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1250 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1251 				break;
1252 			}
1253 			do_start_repo_child = 1;
1254 			break;
1255 		case GOTD_IMSG_DISCONNECT:
1256 			do_disconnect = 1;
1257 			break;
1258 		default:
1259 			log_debug("unexpected imsg %d", imsg.hdr.type);
1260 			break;
1261 		}
1262 
1263 		if (!verify_imsg_src(client, proc, &imsg)) {
1264 			log_debug("dropping imsg type %d from PID %d",
1265 			    imsg.hdr.type, proc->pid);
1266 			imsg_free(&imsg);
1267 			continue;
1268 		}
1269 		if (err)
1270 			log_warnx("uid %d: %s", client->euid, err->msg);
1271 
1272 		if (do_start_repo_child) {
1273 			struct gotd_repo *repo;
1274 			const char *name = client->session->repo_name;
1275 
1276 			repo = gotd_find_repo_by_name(name, &gotd);
1277 			if (repo != NULL) {
1278 				enum gotd_procid proc_type;
1279 
1280 				if (client->required_auth & GOTD_AUTH_WRITE)
1281 					proc_type = PROC_REPO_WRITE;
1282 				else
1283 					proc_type = PROC_REPO_READ;
1284 
1285 				err = start_repo_child(client, proc_type, repo,
1286 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1287 				    gotd.verbosity);
1288 			} else
1289 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1290 
1291 			if (err) {
1292 				log_warnx("uid %d: %s", client->euid, err->msg);
1293 				do_disconnect = 1;
1294 			}
1295 		}
1296 
1297 		if (do_disconnect) {
1298 			if (err)
1299 				disconnect_on_error(client, err);
1300 			else
1301 				disconnect(client);
1302 		}
1303 
1304 		imsg_free(&imsg);
1305 	}
1306 done:
1307 	if (!shut) {
1308 		gotd_imsg_event_add(iev);
1309 	} else {
1310 		/* This pipe is dead. Remove its event handler */
1311 		event_del(&iev->ev);
1312 		disconnect(client);
1313 	}
1314 }
1315 
1316 static void
1317 gotd_dispatch_repo_child(int fd, short event, void *arg)
1318 {
1319 	struct gotd_imsgev *iev = arg;
1320 	struct imsgbuf *ibuf = &iev->ibuf;
1321 	struct gotd_child_proc *proc = NULL;
1322 	struct gotd_client *client;
1323 	ssize_t n;
1324 	int shut = 0;
1325 	struct imsg imsg;
1326 
1327 	client = find_client_by_proc_fd(fd);
1328 	if (client == NULL) {
1329 		/* Can happen during process teardown. */
1330 		warnx("cannot find client for fd %d", fd);
1331 		shut = 1;
1332 		goto done;
1333 	}
1334 
1335 	if (event & EV_READ) {
1336 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1337 			fatal("imsg_read error");
1338 		if (n == 0) {
1339 			/* Connection closed. */
1340 			shut = 1;
1341 			goto done;
1342 		}
1343 	}
1344 
1345 	if (event & EV_WRITE) {
1346 		n = msgbuf_write(&ibuf->w);
1347 		if (n == -1 && errno != EAGAIN)
1348 			fatal("msgbuf_write");
1349 		if (n == 0) {
1350 			/* Connection closed. */
1351 			shut = 1;
1352 			goto done;
1353 		}
1354 	}
1355 
1356 	proc = client->repo;
1357 	if (proc == NULL)
1358 		fatalx("cannot find child process for fd %d", fd);
1359 
1360 	for (;;) {
1361 		const struct got_error *err = NULL;
1362 		uint32_t client_id = 0;
1363 		int do_disconnect = 0;
1364 
1365 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1366 			fatal("%s: imsg_get error", __func__);
1367 		if (n == 0)	/* No more messages. */
1368 			break;
1369 
1370 		switch (imsg.hdr.type) {
1371 		case GOTD_IMSG_ERROR:
1372 			do_disconnect = 1;
1373 			err = gotd_imsg_recv_error(&client_id, &imsg);
1374 			break;
1375 		case GOTD_IMSG_REPO_CHILD_READY:
1376 			err = connect_session(client);
1377 			if (err)
1378 				break;
1379 			err = connect_repo_child(client, proc);
1380 			break;
1381 		default:
1382 			log_debug("unexpected imsg %d", imsg.hdr.type);
1383 			break;
1384 		}
1385 
1386 		if (!verify_imsg_src(client, proc, &imsg)) {
1387 			log_debug("dropping imsg type %d from PID %d",
1388 			    imsg.hdr.type, proc->pid);
1389 			imsg_free(&imsg);
1390 			continue;
1391 		}
1392 		if (err)
1393 			log_warnx("uid %d: %s", client->euid, err->msg);
1394 
1395 		if (do_disconnect) {
1396 			if (err)
1397 				disconnect_on_error(client, err);
1398 			else
1399 				disconnect(client);
1400 		}
1401 
1402 		imsg_free(&imsg);
1403 	}
1404 done:
1405 	if (!shut) {
1406 		gotd_imsg_event_add(iev);
1407 	} else {
1408 		/* This pipe is dead. Remove its event handler */
1409 		event_del(&iev->ev);
1410 		disconnect(client);
1411 	}
1412 }
1413 
1414 static pid_t
1415 start_child(enum gotd_procid proc_id, const char *repo_path,
1416     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1417 {
1418 	char	*argv[11];
1419 	int	 argc = 0;
1420 	pid_t	 pid;
1421 
1422 	switch (pid = fork()) {
1423 	case -1:
1424 		fatal("cannot fork");
1425 	case 0:
1426 		break;
1427 	default:
1428 		close(fd);
1429 		return pid;
1430 	}
1431 
1432 	if (fd != GOTD_FILENO_MSG_PIPE) {
1433 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1434 			fatal("cannot setup imsg fd");
1435 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1436 		fatal("cannot setup imsg fd");
1437 
1438 	argv[argc++] = argv0;
1439 	switch (proc_id) {
1440 	case PROC_LISTEN:
1441 		argv[argc++] = (char *)"-L";
1442 		break;
1443 	case PROC_AUTH:
1444 		argv[argc++] = (char *)"-A";
1445 		break;
1446 	case PROC_SESSION:
1447 		argv[argc++] = (char *)"-S";
1448 		break;
1449 	case PROC_REPO_READ:
1450 		argv[argc++] = (char *)"-R";
1451 		break;
1452 	case PROC_REPO_WRITE:
1453 		argv[argc++] = (char *)"-W";
1454 		break;
1455 	default:
1456 		fatalx("invalid process id %d", proc_id);
1457 	}
1458 
1459 	argv[argc++] = (char *)"-f";
1460 	argv[argc++] = (char *)confpath;
1461 
1462 	if (repo_path) {
1463 		argv[argc++] = (char *)"-P";
1464 		argv[argc++] = (char *)repo_path;
1465 	}
1466 
1467 	if (!daemonize)
1468 		argv[argc++] = (char *)"-d";
1469 	if (verbosity > 0)
1470 		argv[argc++] = (char *)"-v";
1471 	if (verbosity > 1)
1472 		argv[argc++] = (char *)"-v";
1473 	argv[argc++] = NULL;
1474 
1475 	execvp(argv0, argv);
1476 	fatal("execvp");
1477 }
1478 
1479 static void
1480 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1481 {
1482 	struct gotd_child_proc *proc = &gotd.listen_proc;
1483 
1484 	proc->type = PROC_LISTEN;
1485 
1486 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1487 	    PF_UNSPEC, proc->pipe) == -1)
1488 		fatal("socketpair");
1489 
1490 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1491 	    proc->pipe[1], daemonize, verbosity);
1492 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1493 	proc->iev.handler = gotd_dispatch_listener;
1494 	proc->iev.events = EV_READ;
1495 	proc->iev.handler_arg = NULL;
1496 }
1497 
1498 static const struct got_error *
1499 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1500     char *argv0, const char *confpath, int daemonize, int verbosity)
1501 {
1502 	struct gotd_child_proc *proc;
1503 
1504 	proc = calloc(1, sizeof(*proc));
1505 	if (proc == NULL)
1506 		return got_error_from_errno("calloc");
1507 
1508 	proc->type = PROC_SESSION;
1509 	if (strlcpy(proc->repo_name, repo->name,
1510 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1511 		fatalx("repository name too long: %s", repo->name);
1512 	log_debug("starting client uid %d session for repository %s",
1513 	    client->euid, repo->name);
1514 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1515 	    sizeof(proc->repo_path))
1516 		fatalx("repository path too long: %s", repo->path);
1517 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1518 	    PF_UNSPEC, proc->pipe) == -1)
1519 		fatal("socketpair");
1520 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1521 	    confpath, proc->pipe[1], daemonize, verbosity);
1522 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1523 	log_debug("proc %s %s is on fd %d",
1524 	    gotd_proc_names[proc->type], proc->repo_path,
1525 	    proc->pipe[0]);
1526 	proc->iev.handler = gotd_dispatch_client_session;
1527 	proc->iev.events = EV_READ;
1528 	proc->iev.handler_arg = NULL;
1529 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1530 	    gotd_dispatch_client_session, &proc->iev);
1531 	gotd_imsg_event_add(&proc->iev);
1532 
1533 	client->session = proc;
1534 	return NULL;
1535 }
1536 
1537 static const struct got_error *
1538 start_repo_child(struct gotd_client *client, enum gotd_procid proc_type,
1539     struct gotd_repo *repo, char *argv0, const char *confpath,
1540     int daemonize, int verbosity)
1541 {
1542 	struct gotd_child_proc *proc;
1543 
1544 	if (proc_type != PROC_REPO_READ && proc_type != PROC_REPO_WRITE)
1545 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad process type");
1546 
1547 	proc = calloc(1, sizeof(*proc));
1548 	if (proc == NULL)
1549 		return got_error_from_errno("calloc");
1550 
1551 	proc->type = proc_type;
1552 	if (strlcpy(proc->repo_name, repo->name,
1553 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1554 		fatalx("repository name too long: %s", repo->name);
1555 	log_debug("starting %s for repository %s",
1556 	    proc->type == PROC_REPO_READ ? "reader" : "writer", repo->name);
1557 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1558 	    sizeof(proc->repo_path))
1559 		fatalx("repository path too long: %s", repo->path);
1560 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1561 	    PF_UNSPEC, proc->pipe) == -1)
1562 		fatal("socketpair");
1563 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1564 	    confpath, proc->pipe[1], daemonize, verbosity);
1565 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1566 	log_debug("proc %s %s is on fd %d",
1567 	    gotd_proc_names[proc->type], proc->repo_path,
1568 	    proc->pipe[0]);
1569 	proc->iev.handler = gotd_dispatch_repo_child;
1570 	proc->iev.events = EV_READ;
1571 	proc->iev.handler_arg = NULL;
1572 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1573 	    gotd_dispatch_repo_child, &proc->iev);
1574 	gotd_imsg_event_add(&proc->iev);
1575 
1576 	client->repo = proc;
1577 	return NULL;
1578 }
1579 
1580 static const struct got_error *
1581 start_auth_child(struct gotd_client *client, int required_auth,
1582     struct gotd_repo *repo, char *argv0, const char *confpath,
1583     int daemonize, int verbosity)
1584 {
1585 	const struct got_error *err = NULL;
1586 	struct gotd_child_proc *proc;
1587 	struct gotd_imsg_auth iauth;
1588 	int fd;
1589 
1590 	memset(&iauth, 0, sizeof(iauth));
1591 
1592 	fd = dup(client->fd);
1593 	if (fd == -1)
1594 		return got_error_from_errno("dup");
1595 
1596 	proc = calloc(1, sizeof(*proc));
1597 	if (proc == NULL) {
1598 		err = got_error_from_errno("calloc");
1599 		close(fd);
1600 		return err;
1601 	}
1602 
1603 	proc->type = PROC_AUTH;
1604 	if (strlcpy(proc->repo_name, repo->name,
1605 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1606 		fatalx("repository name too long: %s", repo->name);
1607 	log_debug("starting auth for uid %d repository %s",
1608 	    client->euid, repo->name);
1609 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1610 	    sizeof(proc->repo_path))
1611 		fatalx("repository path too long: %s", repo->path);
1612 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1613 	    PF_UNSPEC, proc->pipe) == -1)
1614 		fatal("socketpair");
1615 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1616 	    confpath, proc->pipe[1], daemonize, verbosity);
1617 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1618 	log_debug("proc %s %s is on fd %d",
1619 	    gotd_proc_names[proc->type], proc->repo_path,
1620 	    proc->pipe[0]);
1621 	proc->iev.handler = gotd_dispatch_auth_child;
1622 	proc->iev.events = EV_READ;
1623 	proc->iev.handler_arg = NULL;
1624 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1625 	    gotd_dispatch_auth_child, &proc->iev);
1626 	gotd_imsg_event_add(&proc->iev);
1627 
1628 	iauth.euid = client->euid;
1629 	iauth.egid = client->egid;
1630 	iauth.required_auth = required_auth;
1631 	iauth.client_id = client->id;
1632 	if (gotd_imsg_compose_event(&proc->iev, GOTD_IMSG_AUTHENTICATE,
1633 	    PROC_GOTD, fd, &iauth, sizeof(iauth)) == -1) {
1634 		log_warn("imsg compose AUTHENTICATE");
1635 		close(fd);
1636 		/* Let the auth_timeout handler tidy up. */
1637 	}
1638 
1639 	client->auth = proc;
1640 	client->required_auth = required_auth;
1641 	return NULL;
1642 }
1643 
1644 static void
1645 apply_unveil_repo_readonly(const char *repo_path)
1646 {
1647 	if (unveil(repo_path, "r") == -1)
1648 		fatal("unveil %s", repo_path);
1649 
1650 	if (unveil(NULL, NULL) == -1)
1651 		fatal("unveil");
1652 }
1653 
1654 static void
1655 apply_unveil_repo_readwrite(const char *repo_path)
1656 {
1657 	if (unveil(repo_path, "rwc") == -1)
1658 		fatal("unveil %s", repo_path);
1659 
1660 	if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1661 		fatal("unveil %s", GOT_TMPDIR_STR);
1662 
1663 	if (unveil(NULL, NULL) == -1)
1664 		fatal("unveil");
1665 }
1666 
1667 static void
1668 apply_unveil_none(void)
1669 {
1670 	if (unveil("/", "") == -1)
1671 		fatal("unveil");
1672 
1673 	if (unveil(NULL, NULL) == -1)
1674 		fatal("unveil");
1675 }
1676 
1677 static void
1678 apply_unveil_selfexec(void)
1679 {
1680 	if (unveil(gotd.argv0, "x") == -1)
1681 		fatal("unveil %s", gotd.argv0);
1682 
1683 	if (unveil(NULL, NULL) == -1)
1684 		fatal("unveil");
1685 }
1686 
1687 int
1688 main(int argc, char **argv)
1689 {
1690 	const struct got_error *error = NULL;
1691 	int ch, fd = -1, daemonize = 1, verbosity = 0, noaction = 0;
1692 	const char *confpath = GOTD_CONF_PATH;
1693 	char *argv0 = argv[0];
1694 	char title[2048];
1695 	struct passwd *pw = NULL;
1696 	char *repo_path = NULL;
1697 	enum gotd_procid proc_id = PROC_GOTD;
1698 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1699 	int *pack_fds = NULL, *temp_fds = NULL;
1700 	struct gotd_repo *repo = NULL;
1701 
1702 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1703 
1704 	while ((ch = getopt(argc, argv, "Adf:LnP:RSvW")) != -1) {
1705 		switch (ch) {
1706 		case 'A':
1707 			proc_id = PROC_AUTH;
1708 			break;
1709 		case 'd':
1710 			daemonize = 0;
1711 			break;
1712 		case 'f':
1713 			confpath = optarg;
1714 			break;
1715 		case 'L':
1716 			proc_id = PROC_LISTEN;
1717 			break;
1718 		case 'n':
1719 			noaction = 1;
1720 			break;
1721 		case 'P':
1722 			repo_path = realpath(optarg, NULL);
1723 			if (repo_path == NULL)
1724 				fatal("realpath '%s'", optarg);
1725 			break;
1726 		case 'R':
1727 			proc_id = PROC_REPO_READ;
1728 			break;
1729 		case 'S':
1730 			proc_id = PROC_SESSION;
1731 			break;
1732 		case 'v':
1733 			if (verbosity < 3)
1734 				verbosity++;
1735 			break;
1736 		case 'W':
1737 			proc_id = PROC_REPO_WRITE;
1738 			break;
1739 		default:
1740 			usage();
1741 		}
1742 	}
1743 
1744 	argc -= optind;
1745 	argv += optind;
1746 
1747 	if (argc != 0)
1748 		usage();
1749 
1750 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1751 		fatalx("need root privileges");
1752 
1753 	if (parse_config(confpath, proc_id, &gotd, 1) != 0)
1754 		return 1;
1755 
1756 	pw = getpwnam(gotd.user_name);
1757 	if (pw == NULL)
1758 		fatalx("user %s not found", gotd.user_name);
1759 
1760 	if (pw->pw_uid == 0)
1761 		fatalx("cannot run %s as the superuser", getprogname());
1762 
1763 	if (noaction) {
1764 		fprintf(stderr, "configuration OK\n");
1765 		return 0;
1766 	}
1767 
1768 	gotd.argv0 = argv0;
1769 	gotd.daemonize = daemonize;
1770 	gotd.verbosity = verbosity;
1771 	gotd.confpath = confpath;
1772 
1773 	/* Require an absolute path in argv[0] for reliable re-exec. */
1774 	if (!got_path_is_absolute(argv0))
1775 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1776 
1777 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1778 	log_setverbose(verbosity);
1779 
1780 	if (proc_id == PROC_GOTD) {
1781 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1782 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1783 		if (daemonize && daemon(1, 0) == -1)
1784 			fatal("daemon");
1785 		gotd.pid = getpid();
1786 		start_listener(argv0, confpath, daemonize, verbosity);
1787 	} else if (proc_id == PROC_LISTEN) {
1788 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1789 		if (verbosity) {
1790 			log_info("socket: %s", gotd.unix_socket_path);
1791 			log_info("user: %s", pw->pw_name);
1792 		}
1793 
1794 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1795 		    pw->pw_gid);
1796 		if (fd == -1) {
1797 			fatal("cannot listen on unix socket %s",
1798 			    gotd.unix_socket_path);
1799 		}
1800 	} else if (proc_id == PROC_AUTH) {
1801 		snprintf(title, sizeof(title), "%s %s",
1802 		    gotd_proc_names[proc_id], repo_path);
1803 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1804 	    proc_id == PROC_SESSION) {
1805 		error = got_repo_pack_fds_open(&pack_fds);
1806 		if (error != NULL)
1807 			fatalx("cannot open pack tempfiles: %s", error->msg);
1808 		error = got_repo_temp_fds_open(&temp_fds);
1809 		if (error != NULL)
1810 			fatalx("cannot open pack tempfiles: %s", error->msg);
1811 		if (repo_path == NULL)
1812 			fatalx("repository path not specified");
1813 		snprintf(title, sizeof(title), "%s %s",
1814 		    gotd_proc_names[proc_id], repo_path);
1815 	} else
1816 		fatal("invalid process id %d", proc_id);
1817 
1818 	setproctitle("%s", title);
1819 	log_procinit(title);
1820 
1821 	/* Drop root privileges. */
1822 	if (setgid(pw->pw_gid) == -1)
1823 		fatal("setgid %d failed", pw->pw_gid);
1824 	if (setuid(pw->pw_uid) == -1)
1825 		fatal("setuid %d failed", pw->pw_uid);
1826 
1827 	event_init();
1828 
1829 	switch (proc_id) {
1830 	case PROC_GOTD:
1831 #ifndef PROFILE
1832 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1833 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1834 			err(1, "pledge");
1835 #endif
1836 		break;
1837 	case PROC_LISTEN:
1838 #ifndef PROFILE
1839 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1840 			err(1, "pledge");
1841 #endif
1842 		/*
1843 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1844 		 * sockets by revoking all filesystem access via unveil(2).
1845 		 */
1846 		apply_unveil_none();
1847 
1848 		listen_main(title, fd, gotd.connection_limits,
1849 		    gotd.nconnection_limits);
1850 		/* NOTREACHED */
1851 		break;
1852 	case PROC_AUTH:
1853 #ifndef PROFILE
1854 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1855 			err(1, "pledge");
1856 #endif
1857 		/*
1858 		 * We need the "unix" pledge promise for getpeername(2) only.
1859 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1860 		 * filesystem access via unveil(2). Access to password database
1861 		 * files will still work since "getpw" bypasses unveil(2).
1862 		 */
1863 		apply_unveil_none();
1864 
1865 		auth_main(title, &gotd.repos, repo_path);
1866 		/* NOTREACHED */
1867 		break;
1868 	case PROC_SESSION:
1869 #ifndef PROFILE
1870 		/*
1871 		 * The "recvfd" promise is only needed during setup and
1872 		 * will be removed in a later pledge(2) call.
1873 		 */
1874 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1875 		    "unveil", NULL) == -1)
1876 			err(1, "pledge");
1877 #endif
1878 		apply_unveil_repo_readwrite(repo_path);
1879 		session_main(title, repo_path, pack_fds, temp_fds,
1880 		    &gotd.request_timeout);
1881 		/* NOTREACHED */
1882 		break;
1883 	case PROC_REPO_READ:
1884 #ifndef PROFILE
1885 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1886 			err(1, "pledge");
1887 #endif
1888 		apply_unveil_repo_readonly(repo_path);
1889 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1890 		/* NOTREACHED */
1891 		exit(0);
1892 	case PROC_REPO_WRITE:
1893 #ifndef PROFILE
1894 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1895 			err(1, "pledge");
1896 #endif
1897 		apply_unveil_repo_readonly(repo_path);
1898 		repo = gotd_find_repo_by_path(repo_path, &gotd);
1899 		if (repo == NULL)
1900 			fatalx("no repository for path %s", repo_path);
1901 		repo_write_main(title, repo_path, pack_fds, temp_fds,
1902 		    &repo->protected_tag_namespaces,
1903 		    &repo->protected_branch_namespaces,
1904 		    &repo->protected_branches);
1905 		/* NOTREACHED */
1906 		exit(0);
1907 	default:
1908 		fatal("invalid process id %d", proc_id);
1909 	}
1910 
1911 	if (proc_id != PROC_GOTD)
1912 		fatal("invalid process id %d", proc_id);
1913 
1914 	apply_unveil_selfexec();
1915 
1916 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1917 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1918 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1919 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1920 	signal(SIGPIPE, SIG_IGN);
1921 
1922 	signal_add(&evsigint, NULL);
1923 	signal_add(&evsigterm, NULL);
1924 	signal_add(&evsighup, NULL);
1925 	signal_add(&evsigusr1, NULL);
1926 
1927 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1928 
1929 	event_dispatch();
1930 
1931 	free(repo_path);
1932 	gotd_shutdown();
1933 
1934 	return 0;
1935 }