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 struct gotd_repo *
500 find_repo_by_name(const char *repo_name)
501 {
502 	struct gotd_repo *repo;
503 	size_t namelen;
504 
505 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
506 		namelen = strlen(repo->name);
507 		if (strncmp(repo->name, repo_name, namelen) != 0)
508 			continue;
509 		if (repo_name[namelen] == '\0' ||
510 		    strcmp(&repo_name[namelen], ".git") == 0)
511 			return repo;
512 	}
513 
514 	return NULL;
515 }
516 
517 static const struct got_error *
518 start_client_authentication(struct gotd_client *client, struct imsg *imsg)
519 {
520 	const struct got_error *err;
521 	struct gotd_imsg_list_refs ireq;
522 	struct gotd_repo *repo = NULL;
523 	size_t datalen;
524 
525 	log_debug("list-refs request from uid %d", client->euid);
526 
527 	if (client->state != GOTD_CLIENT_STATE_NEW)
528 		return got_error_msg(GOT_ERR_BAD_REQUEST,
529 		    "unexpected list-refs request received");
530 
531 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
532 	if (datalen != sizeof(ireq))
533 		return got_error(GOT_ERR_PRIVSEP_LEN);
534 
535 	memcpy(&ireq, imsg->data, datalen);
536 
537 	if (ireq.client_is_reading) {
538 		err = ensure_client_is_not_writing(client);
539 		if (err)
540 			return err;
541 		repo = find_repo_by_name(ireq.repo_name);
542 		if (repo == NULL)
543 			return got_error(GOT_ERR_NOT_GIT_REPO);
544 		err = start_auth_child(client, GOTD_AUTH_READ, repo,
545 		    gotd.argv0, gotd.confpath, gotd.daemonize,
546 		    gotd.verbosity);
547 		if (err)
548 			return err;
549 	} else {
550 		err = ensure_client_is_not_reading(client);
551 		if (err)
552 			return err;
553 		repo = find_repo_by_name(ireq.repo_name);
554 		if (repo == NULL)
555 			return got_error(GOT_ERR_NOT_GIT_REPO);
556 		err = start_auth_child(client,
557 		    GOTD_AUTH_READ | GOTD_AUTH_WRITE,
558 		    repo, gotd.argv0, gotd.confpath, gotd.daemonize,
559 		    gotd.verbosity);
560 		if (err)
561 			return err;
562 	}
563 
564 	evtimer_add(&client->tmo, &auth_timeout);
565 
566 	/* Flow continues upon authentication successs/failure or timeout. */
567 	return NULL;
568 }
569 
570 static void
571 gotd_request(int fd, short events, void *arg)
572 {
573 	struct gotd_imsgev *iev = arg;
574 	struct imsgbuf *ibuf = &iev->ibuf;
575 	struct gotd_client *client = iev->handler_arg;
576 	const struct got_error *err = NULL;
577 	struct imsg imsg;
578 	ssize_t n;
579 
580 	if (events & EV_WRITE) {
581 		while (ibuf->w.queued) {
582 			n = msgbuf_write(&ibuf->w);
583 			if (n == -1 && errno == EPIPE) {
584 				/*
585 				 * The client has closed its socket.
586 				 * This can happen when Git clients are
587 				 * done sending pack file data.
588 				 */
589 				msgbuf_clear(&ibuf->w);
590 				continue;
591 			} else if (n == -1 && errno != EAGAIN) {
592 				err = got_error_from_errno("imsg_flush");
593 				disconnect_on_error(client, err);
594 				return;
595 			}
596 			if (n == 0) {
597 				/* Connection closed. */
598 				err = got_error(GOT_ERR_EOF);
599 				disconnect_on_error(client, err);
600 				return;
601 			}
602 		}
603 
604 		/* Disconnect gotctl(8) now that messages have been sent. */
605 		if (!client_is_reading(client) && !client_is_writing(client)) {
606 			disconnect(client);
607 			return;
608 		}
609 	}
610 
611 	if ((events & EV_READ) == 0)
612 		return;
613 
614 	memset(&imsg, 0, sizeof(imsg));
615 
616 	while (err == NULL) {
617 		err = gotd_imsg_recv(&imsg, ibuf, 0);
618 		if (err) {
619 			if (err->code == GOT_ERR_PRIVSEP_READ)
620 				err = NULL;
621 			break;
622 		}
623 
624 		evtimer_del(&client->tmo);
625 
626 		switch (imsg.hdr.type) {
627 		case GOTD_IMSG_INFO:
628 			err = send_info(client);
629 			break;
630 		case GOTD_IMSG_STOP:
631 			err = stop_gotd(client);
632 			break;
633 		case GOTD_IMSG_LIST_REFS:
634 			err = start_client_authentication(client, &imsg);
635 			break;
636 		default:
637 			log_debug("unexpected imsg %d", imsg.hdr.type);
638 			err = got_error(GOT_ERR_PRIVSEP_MSG);
639 			break;
640 		}
641 
642 		imsg_free(&imsg);
643 	}
644 
645 	if (err) {
646 		disconnect_on_error(client, err);
647 	} else {
648 		gotd_imsg_event_add(&client->iev);
649 	}
650 }
651 
652 static void
653 gotd_auth_timeout(int fd, short events, void *arg)
654 {
655 	struct gotd_client *client = arg;
656 
657 	log_debug("disconnecting uid %d due to authentication timeout",
658 	    client->euid);
659 	disconnect(client);
660 }
661 
662 static const struct got_error *
663 recv_connect(uint32_t *client_id, struct imsg *imsg)
664 {
665 	const struct got_error *err = NULL;
666 	struct gotd_imsg_connect iconnect;
667 	size_t datalen;
668 	int s = -1;
669 	struct gotd_client *client = NULL;
670 
671 	*client_id = 0;
672 
673 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
674 	if (datalen != sizeof(iconnect))
675 		return got_error(GOT_ERR_PRIVSEP_LEN);
676 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
677 
678 	s = imsg->fd;
679 	if (s == -1) {
680 		err = got_error(GOT_ERR_PRIVSEP_NO_FD);
681 		goto done;
682 	}
683 
684 	if (find_client(iconnect.client_id)) {
685 		err = got_error_msg(GOT_ERR_CLIENT_ID, "duplicate client ID");
686 		goto done;
687 	}
688 
689 	client = calloc(1, sizeof(*client));
690 	if (client == NULL) {
691 		err = got_error_from_errno("calloc");
692 		goto done;
693 	}
694 
695 	*client_id = iconnect.client_id;
696 
697 	client->state = GOTD_CLIENT_STATE_NEW;
698 	client->id = iconnect.client_id;
699 	client->fd = s;
700 	s = -1;
701 	/* The auth process will verify UID/GID for us. */
702 	client->euid = iconnect.euid;
703 	client->egid = iconnect.egid;
704 
705 	imsg_init(&client->iev.ibuf, client->fd);
706 	client->iev.handler = gotd_request;
707 	client->iev.events = EV_READ;
708 	client->iev.handler_arg = client;
709 
710 	event_set(&client->iev.ev, client->fd, EV_READ, gotd_request,
711 	    &client->iev);
712 	gotd_imsg_event_add(&client->iev);
713 
714 	evtimer_set(&client->tmo, gotd_auth_timeout, client);
715 
716 	add_client(client);
717 	log_debug("%s: new client uid %d connected on fd %d", __func__,
718 	    client->euid, client->fd);
719 done:
720 	if (err) {
721 		struct gotd_child_proc *listen_proc = &gotd.listen_proc;
722 		struct gotd_imsg_disconnect idisconnect;
723 
724 		idisconnect.client_id = client->id;
725 		if (gotd_imsg_compose_event(&listen_proc->iev,
726 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
727 		    &idisconnect, sizeof(idisconnect)) == -1)
728 			log_warn("imsg compose DISCONNECT");
729 
730 		if (s != -1)
731 			close(s);
732 	}
733 
734 	return err;
735 }
736 
737 static const char *gotd_proc_names[PROC_MAX] = {
738 	"parent",
739 	"listen",
740 	"auth",
741 	"session",
742 	"repo_read",
743 	"repo_write"
744 };
745 
746 static void
747 kill_proc(struct gotd_child_proc *proc, int fatal)
748 {
749 	if (fatal) {
750 		log_warnx("sending SIGKILL to PID %d", proc->pid);
751 		kill(proc->pid, SIGKILL);
752 	} else
753 		kill(proc->pid, SIGTERM);
754 }
755 
756 static void
757 gotd_shutdown(void)
758 {
759 	struct gotd_child_proc *proc;
760 	uint64_t slot;
761 
762 	log_debug("shutting down");
763 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
764 		struct gotd_client *c, *tmp;
765 
766 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
767 			disconnect(c);
768 	}
769 
770 	proc = &gotd.listen_proc;
771 	msgbuf_clear(&proc->iev.ibuf.w);
772 	close(proc->iev.ibuf.fd);
773 	kill_proc(proc, 0);
774 	wait_for_child(proc->pid);
775 
776 	log_info("terminating");
777 	exit(0);
778 }
779 
780 void
781 gotd_sighdlr(int sig, short event, void *arg)
782 {
783 	/*
784 	 * Normal signal handler rules don't apply because libevent
785 	 * decouples for us.
786 	 */
787 
788 	switch (sig) {
789 	case SIGHUP:
790 		log_info("%s: ignoring SIGHUP", __func__);
791 		break;
792 	case SIGUSR1:
793 		log_info("%s: ignoring SIGUSR1", __func__);
794 		break;
795 	case SIGTERM:
796 	case SIGINT:
797 		gotd_shutdown();
798 		break;
799 	default:
800 		fatalx("unexpected signal");
801 	}
802 }
803 
804 static const struct got_error *
805 ensure_proc_is_reading(struct gotd_client *client,
806     struct gotd_child_proc *proc)
807 {
808 	if (!client_is_reading(client)) {
809 		kill_proc(proc, 1);
810 		return got_error_fmt(GOT_ERR_BAD_PACKET,
811 		    "PID %d handled a read-request for uid %d but this "
812 		    "user is not reading from a repository", proc->pid,
813 		    client->euid);
814 	}
815 
816 	return NULL;
817 }
818 
819 static const struct got_error *
820 ensure_proc_is_writing(struct gotd_client *client,
821     struct gotd_child_proc *proc)
822 {
823 	if (!client_is_writing(client)) {
824 		kill_proc(proc, 1);
825 		return got_error_fmt(GOT_ERR_BAD_PACKET,
826 		    "PID %d handled a write-request for uid %d but this "
827 		    "user is not writing to a repository", proc->pid,
828 		    client->euid);
829 	}
830 
831 	return NULL;
832 }
833 
834 static int
835 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
836     struct imsg *imsg)
837 {
838 	const struct got_error *err;
839 	int ret = 0;
840 
841 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
842 		if (client->repo == NULL)
843 			fatalx("no process found for uid %d", client->euid);
844 		if (proc->pid != client->repo->pid) {
845 			kill_proc(proc, 1);
846 			log_warnx("received message from PID %d for uid %d, "
847 			    "while PID %d is the process serving this user",
848 			    proc->pid, client->euid, client->repo->pid);
849 			return 0;
850 		}
851 	}
852 	if (proc->type == PROC_SESSION) {
853 		if (client->session == NULL) {
854 			log_warnx("no session found for uid %d", client->euid);
855 			return 0;
856 		}
857 		if (proc->pid != client->session->pid) {
858 			kill_proc(proc, 1);
859 			log_warnx("received message from PID %d for uid %d, "
860 			    "while PID %d is the process serving this user",
861 			    proc->pid, client->euid, client->session->pid);
862 			return 0;
863 		}
864 	}
865 
866 	switch (imsg->hdr.type) {
867 	case GOTD_IMSG_ERROR:
868 		ret = 1;
869 		break;
870 	case GOTD_IMSG_CONNECT:
871 		if (proc->type != PROC_LISTEN) {
872 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
873 			    "new connection for uid %d from PID %d "
874 			    "which is not the listen process",
875 			    proc->pid, client->euid);
876 		} else
877 			ret = 1;
878 		break;
879 	case GOTD_IMSG_ACCESS_GRANTED:
880 		if (proc->type != PROC_AUTH) {
881 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
882 			    "authentication of uid %d from PID %d "
883 			    "which is not the auth process",
884 			    proc->pid, client->euid);
885 		} else
886 			ret = 1;
887 		break;
888 	case GOTD_IMSG_CLIENT_SESSION_READY:
889 		if (proc->type != PROC_SESSION) {
890 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
891 			    "unexpected \"ready\" signal from PID %d",
892 			    proc->pid);
893 		} else
894 			ret = 1;
895 		break;
896 	case GOTD_IMSG_REPO_CHILD_READY:
897 		if (proc->type != PROC_REPO_READ &&
898 		    proc->type != PROC_REPO_WRITE) {
899 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
900 			    "unexpected \"ready\" signal from PID %d",
901 			    proc->pid);
902 		} else
903 			ret = 1;
904 		break;
905 	case GOTD_IMSG_PACKFILE_DONE:
906 		err = ensure_proc_is_reading(client, proc);
907 		if (err)
908 			log_warnx("uid %d: %s", client->euid, err->msg);
909 		else
910 			ret = 1;
911 		break;
912 	case GOTD_IMSG_PACKFILE_INSTALL:
913 	case GOTD_IMSG_REF_UPDATES_START:
914 	case GOTD_IMSG_REF_UPDATE:
915 		err = ensure_proc_is_writing(client, proc);
916 		if (err)
917 			log_warnx("uid %d: %s", client->euid, err->msg);
918 		else
919 			ret = 1;
920 		break;
921 	default:
922 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
923 		break;
924 	}
925 
926 	return ret;
927 }
928 
929 static const struct got_error *
930 connect_repo_child(struct gotd_client *client,
931     struct gotd_child_proc *repo_proc)
932 {
933 	static const struct got_error *err;
934 	struct gotd_imsgev *session_iev = &client->session->iev;
935 	struct gotd_imsg_connect_repo_child ireq;
936 	int pipe[2];
937 
938 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
939 		return got_error_msg(GOT_ERR_BAD_REQUEST,
940 		    "unexpected repo child ready signal received");
941 
942 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
943 	    PF_UNSPEC, pipe) == -1)
944 		fatal("socketpair");
945 
946 	memset(&ireq, 0, sizeof(ireq));
947 	ireq.client_id = client->id;
948 	ireq.proc_id = repo_proc->type;
949 
950 	/* Pass repo child pipe to session child process. */
951 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
952 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
953 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
954 		close(pipe[0]);
955 		close(pipe[1]);
956 		return err;
957 	}
958 
959 	/* Pass session child pipe to repo child process. */
960 	if (gotd_imsg_compose_event(&repo_proc->iev,
961 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
962 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
963 		close(pipe[1]);
964 		return err;
965 	}
966 
967 	return NULL;
968 }
969 
970 static void
971 gotd_dispatch_listener(int fd, short event, void *arg)
972 {
973 	struct gotd_imsgev *iev = arg;
974 	struct imsgbuf *ibuf = &iev->ibuf;
975 	struct gotd_child_proc *proc = &gotd.listen_proc;
976 	ssize_t n;
977 	int shut = 0;
978 	struct imsg imsg;
979 
980 	if (proc->iev.ibuf.fd != fd)
981 		fatalx("%s: unexpected fd %d", __func__, fd);
982 
983 	if (event & EV_READ) {
984 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
985 			fatal("imsg_read error");
986 		if (n == 0) {
987 			/* Connection closed. */
988 			shut = 1;
989 			goto done;
990 		}
991 	}
992 
993 	if (event & EV_WRITE) {
994 		n = msgbuf_write(&ibuf->w);
995 		if (n == -1 && errno != EAGAIN)
996 			fatal("msgbuf_write");
997 		if (n == 0) {
998 			/* Connection closed. */
999 			shut = 1;
1000 			goto done;
1001 		}
1002 	}
1003 
1004 	for (;;) {
1005 		const struct got_error *err = NULL;
1006 		struct gotd_client *client = NULL;
1007 		uint32_t client_id = 0;
1008 		int do_disconnect = 0;
1009 
1010 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1011 			fatal("%s: imsg_get error", __func__);
1012 		if (n == 0)	/* No more messages. */
1013 			break;
1014 
1015 		switch (imsg.hdr.type) {
1016 		case GOTD_IMSG_ERROR:
1017 			do_disconnect = 1;
1018 			err = gotd_imsg_recv_error(&client_id, &imsg);
1019 			break;
1020 		case GOTD_IMSG_CONNECT:
1021 			err = recv_connect(&client_id, &imsg);
1022 			break;
1023 		default:
1024 			log_debug("unexpected imsg %d", imsg.hdr.type);
1025 			break;
1026 		}
1027 
1028 		client = find_client(client_id);
1029 		if (client == NULL) {
1030 			log_warnx("%s: client not found", __func__);
1031 			imsg_free(&imsg);
1032 			continue;
1033 		}
1034 
1035 		if (err)
1036 			log_warnx("uid %d: %s", client->euid, err->msg);
1037 
1038 		if (do_disconnect) {
1039 			if (err)
1040 				disconnect_on_error(client, err);
1041 			else
1042 				disconnect(client);
1043 		}
1044 
1045 		imsg_free(&imsg);
1046 	}
1047 done:
1048 	if (!shut) {
1049 		gotd_imsg_event_add(iev);
1050 	} else {
1051 		/* This pipe is dead. Remove its event handler */
1052 		event_del(&iev->ev);
1053 		event_loopexit(NULL);
1054 	}
1055 }
1056 
1057 static void
1058 gotd_dispatch_auth_child(int fd, short event, void *arg)
1059 {
1060 	const struct got_error *err = NULL;
1061 	struct gotd_imsgev *iev = arg;
1062 	struct imsgbuf *ibuf = &iev->ibuf;
1063 	struct gotd_client *client;
1064 	struct gotd_repo *repo = NULL;
1065 	ssize_t n;
1066 	int shut = 0;
1067 	struct imsg imsg;
1068 	uint32_t client_id = 0;
1069 	int do_disconnect = 0;
1070 
1071 	client = find_client_by_proc_fd(fd);
1072 	if (client == NULL) {
1073 		/* Can happen during process teardown. */
1074 		warnx("cannot find client for fd %d", fd);
1075 		shut = 1;
1076 		goto done;
1077 	}
1078 
1079 	if (client->auth == NULL)
1080 		fatalx("cannot find auth child process for fd %d", fd);
1081 
1082 	if (event & EV_READ) {
1083 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1084 			fatal("imsg_read error");
1085 		if (n == 0) {
1086 			/* Connection closed. */
1087 			shut = 1;
1088 			goto done;
1089 		}
1090 	}
1091 
1092 	if (event & EV_WRITE) {
1093 		n = msgbuf_write(&ibuf->w);
1094 		if (n == -1 && errno != EAGAIN)
1095 			fatal("msgbuf_write");
1096 		if (n == 0) {
1097 			/* Connection closed. */
1098 			shut = 1;
1099 		}
1100 		goto done;
1101 	}
1102 
1103 	if (client->auth->iev.ibuf.fd != fd)
1104 		fatalx("%s: unexpected fd %d", __func__, fd);
1105 
1106 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1107 		fatal("%s: imsg_get error", __func__);
1108 	if (n == 0)	/* No more messages. */
1109 		return;
1110 
1111 	evtimer_del(&client->tmo);
1112 
1113 	switch (imsg.hdr.type) {
1114 	case GOTD_IMSG_ERROR:
1115 		do_disconnect = 1;
1116 		err = gotd_imsg_recv_error(&client_id, &imsg);
1117 		break;
1118 	case GOTD_IMSG_ACCESS_GRANTED:
1119 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1120 		break;
1121 	default:
1122 		do_disconnect = 1;
1123 		log_debug("unexpected imsg %d", imsg.hdr.type);
1124 		break;
1125 	}
1126 
1127 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1128 		do_disconnect = 1;
1129 		log_debug("dropping imsg type %d from PID %d",
1130 		    imsg.hdr.type, client->auth->pid);
1131 	}
1132 	imsg_free(&imsg);
1133 
1134 	if (do_disconnect) {
1135 		if (err)
1136 			disconnect_on_error(client, err);
1137 		else
1138 			disconnect(client);
1139 		goto done;
1140 	}
1141 
1142 	repo = find_repo_by_name(client->auth->repo_name);
1143 	if (repo == NULL) {
1144 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1145 		goto done;
1146 	}
1147 	kill_auth_proc(client);
1148 
1149 	log_info("authenticated uid %d for repository %s",
1150 	    client->euid, repo->name);
1151 
1152 	err = start_session_child(client, repo, gotd.argv0,
1153 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1154 	if (err)
1155 		goto done;
1156 done:
1157 	if (err)
1158 		log_warnx("uid %d: %s", client->euid, err->msg);
1159 
1160 	/* We might have killed the auth process by now. */
1161 	if (client->auth != NULL) {
1162 		if (!shut) {
1163 			gotd_imsg_event_add(iev);
1164 		} else {
1165 			/* This pipe is dead. Remove its event handler */
1166 			event_del(&iev->ev);
1167 		}
1168 	}
1169 }
1170 
1171 static const struct got_error *
1172 connect_session(struct gotd_client *client)
1173 {
1174 	const struct got_error *err = NULL;
1175 	struct gotd_imsg_connect iconnect;
1176 	int s;
1177 
1178 	memset(&iconnect, 0, sizeof(iconnect));
1179 
1180 	s = dup(client->fd);
1181 	if (s == -1)
1182 		return got_error_from_errno("dup");
1183 
1184 	iconnect.client_id = client->id;
1185 	iconnect.euid = client->euid;
1186 	iconnect.egid = client->egid;
1187 
1188 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1189 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1190 		err = got_error_from_errno("imsg compose CONNECT");
1191 		close(s);
1192 		return err;
1193 	}
1194 
1195 	/*
1196 	 * We are no longer interested in messages from this client.
1197 	 * Further client requests will be handled by the session process.
1198 	 */
1199 	msgbuf_clear(&client->iev.ibuf.w);
1200 	imsg_clear(&client->iev.ibuf);
1201 	event_del(&client->iev.ev);
1202 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1203 
1204 	return NULL;
1205 }
1206 
1207 static void
1208 gotd_dispatch_client_session(int fd, short event, void *arg)
1209 {
1210 	struct gotd_imsgev *iev = arg;
1211 	struct imsgbuf *ibuf = &iev->ibuf;
1212 	struct gotd_child_proc *proc = NULL;
1213 	struct gotd_client *client = NULL;
1214 	ssize_t n;
1215 	int shut = 0;
1216 	struct imsg imsg;
1217 
1218 	client = find_client_by_proc_fd(fd);
1219 	if (client == NULL) {
1220 		/* Can happen during process teardown. */
1221 		warnx("cannot find client for fd %d", fd);
1222 		shut = 1;
1223 		goto done;
1224 	}
1225 
1226 	if (event & EV_READ) {
1227 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1228 			fatal("imsg_read error");
1229 		if (n == 0) {
1230 			/* Connection closed. */
1231 			shut = 1;
1232 			goto done;
1233 		}
1234 	}
1235 
1236 	if (event & EV_WRITE) {
1237 		n = msgbuf_write(&ibuf->w);
1238 		if (n == -1 && errno != EAGAIN)
1239 			fatal("msgbuf_write");
1240 		if (n == 0) {
1241 			/* Connection closed. */
1242 			shut = 1;
1243 			goto done;
1244 		}
1245 	}
1246 
1247 	proc = client->session;
1248 	if (proc == NULL)
1249 		fatalx("cannot find session child process for fd %d", fd);
1250 
1251 	for (;;) {
1252 		const struct got_error *err = NULL;
1253 		uint32_t client_id = 0;
1254 		int do_disconnect = 0, do_start_repo_child = 0;
1255 
1256 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1257 			fatal("%s: imsg_get error", __func__);
1258 		if (n == 0)	/* No more messages. */
1259 			break;
1260 
1261 		switch (imsg.hdr.type) {
1262 		case GOTD_IMSG_ERROR:
1263 			do_disconnect = 1;
1264 			err = gotd_imsg_recv_error(&client_id, &imsg);
1265 			break;
1266 		case GOTD_IMSG_CLIENT_SESSION_READY:
1267 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1268 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1269 				break;
1270 			}
1271 			do_start_repo_child = 1;
1272 			break;
1273 		case GOTD_IMSG_DISCONNECT:
1274 			do_disconnect = 1;
1275 			break;
1276 		default:
1277 			log_debug("unexpected imsg %d", imsg.hdr.type);
1278 			break;
1279 		}
1280 
1281 		if (!verify_imsg_src(client, proc, &imsg)) {
1282 			log_debug("dropping imsg type %d from PID %d",
1283 			    imsg.hdr.type, proc->pid);
1284 			imsg_free(&imsg);
1285 			continue;
1286 		}
1287 		if (err)
1288 			log_warnx("uid %d: %s", client->euid, err->msg);
1289 
1290 		if (do_start_repo_child) {
1291 			struct gotd_repo *repo;
1292 
1293 			repo = find_repo_by_name(client->session->repo_name);
1294 			if (repo != NULL) {
1295 				enum gotd_procid proc_type;
1296 
1297 				if (client->required_auth & GOTD_AUTH_WRITE)
1298 					proc_type = PROC_REPO_WRITE;
1299 				else
1300 					proc_type = PROC_REPO_READ;
1301 
1302 				err = start_repo_child(client, proc_type, repo,
1303 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1304 				    gotd.verbosity);
1305 			} else
1306 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1307 
1308 			if (err) {
1309 				log_warnx("uid %d: %s", client->euid, err->msg);
1310 				do_disconnect = 1;
1311 			}
1312 		}
1313 
1314 		if (do_disconnect) {
1315 			if (err)
1316 				disconnect_on_error(client, err);
1317 			else
1318 				disconnect(client);
1319 		}
1320 
1321 		imsg_free(&imsg);
1322 	}
1323 done:
1324 	if (!shut) {
1325 		gotd_imsg_event_add(iev);
1326 	} else {
1327 		/* This pipe is dead. Remove its event handler */
1328 		event_del(&iev->ev);
1329 		disconnect(client);
1330 	}
1331 }
1332 
1333 static void
1334 gotd_dispatch_repo_child(int fd, short event, void *arg)
1335 {
1336 	struct gotd_imsgev *iev = arg;
1337 	struct imsgbuf *ibuf = &iev->ibuf;
1338 	struct gotd_child_proc *proc = NULL;
1339 	struct gotd_client *client;
1340 	ssize_t n;
1341 	int shut = 0;
1342 	struct imsg imsg;
1343 
1344 	client = find_client_by_proc_fd(fd);
1345 	if (client == NULL) {
1346 		/* Can happen during process teardown. */
1347 		warnx("cannot find client for fd %d", fd);
1348 		shut = 1;
1349 		goto done;
1350 	}
1351 
1352 	if (event & EV_READ) {
1353 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1354 			fatal("imsg_read error");
1355 		if (n == 0) {
1356 			/* Connection closed. */
1357 			shut = 1;
1358 			goto done;
1359 		}
1360 	}
1361 
1362 	if (event & EV_WRITE) {
1363 		n = msgbuf_write(&ibuf->w);
1364 		if (n == -1 && errno != EAGAIN)
1365 			fatal("msgbuf_write");
1366 		if (n == 0) {
1367 			/* Connection closed. */
1368 			shut = 1;
1369 			goto done;
1370 		}
1371 	}
1372 
1373 	proc = client->repo;
1374 	if (proc == NULL)
1375 		fatalx("cannot find child process for fd %d", fd);
1376 
1377 	for (;;) {
1378 		const struct got_error *err = NULL;
1379 		uint32_t client_id = 0;
1380 		int do_disconnect = 0;
1381 
1382 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1383 			fatal("%s: imsg_get error", __func__);
1384 		if (n == 0)	/* No more messages. */
1385 			break;
1386 
1387 		switch (imsg.hdr.type) {
1388 		case GOTD_IMSG_ERROR:
1389 			do_disconnect = 1;
1390 			err = gotd_imsg_recv_error(&client_id, &imsg);
1391 			break;
1392 		case GOTD_IMSG_REPO_CHILD_READY:
1393 			err = connect_session(client);
1394 			if (err)
1395 				break;
1396 			err = connect_repo_child(client, proc);
1397 			break;
1398 		default:
1399 			log_debug("unexpected imsg %d", imsg.hdr.type);
1400 			break;
1401 		}
1402 
1403 		if (!verify_imsg_src(client, proc, &imsg)) {
1404 			log_debug("dropping imsg type %d from PID %d",
1405 			    imsg.hdr.type, proc->pid);
1406 			imsg_free(&imsg);
1407 			continue;
1408 		}
1409 		if (err)
1410 			log_warnx("uid %d: %s", client->euid, err->msg);
1411 
1412 		if (do_disconnect) {
1413 			if (err)
1414 				disconnect_on_error(client, err);
1415 			else
1416 				disconnect(client);
1417 		}
1418 
1419 		imsg_free(&imsg);
1420 	}
1421 done:
1422 	if (!shut) {
1423 		gotd_imsg_event_add(iev);
1424 	} else {
1425 		/* This pipe is dead. Remove its event handler */
1426 		event_del(&iev->ev);
1427 		disconnect(client);
1428 	}
1429 }
1430 
1431 static pid_t
1432 start_child(enum gotd_procid proc_id, const char *repo_path,
1433     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1434 {
1435 	char	*argv[11];
1436 	int	 argc = 0;
1437 	pid_t	 pid;
1438 
1439 	switch (pid = fork()) {
1440 	case -1:
1441 		fatal("cannot fork");
1442 	case 0:
1443 		break;
1444 	default:
1445 		close(fd);
1446 		return pid;
1447 	}
1448 
1449 	if (fd != GOTD_FILENO_MSG_PIPE) {
1450 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1451 			fatal("cannot setup imsg fd");
1452 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1453 		fatal("cannot setup imsg fd");
1454 
1455 	argv[argc++] = argv0;
1456 	switch (proc_id) {
1457 	case PROC_LISTEN:
1458 		argv[argc++] = (char *)"-L";
1459 		break;
1460 	case PROC_AUTH:
1461 		argv[argc++] = (char *)"-A";
1462 		break;
1463 	case PROC_SESSION:
1464 		argv[argc++] = (char *)"-S";
1465 		break;
1466 	case PROC_REPO_READ:
1467 		argv[argc++] = (char *)"-R";
1468 		break;
1469 	case PROC_REPO_WRITE:
1470 		argv[argc++] = (char *)"-W";
1471 		break;
1472 	default:
1473 		fatalx("invalid process id %d", proc_id);
1474 	}
1475 
1476 	argv[argc++] = (char *)"-f";
1477 	argv[argc++] = (char *)confpath;
1478 
1479 	if (repo_path) {
1480 		argv[argc++] = (char *)"-P";
1481 		argv[argc++] = (char *)repo_path;
1482 	}
1483 
1484 	if (!daemonize)
1485 		argv[argc++] = (char *)"-d";
1486 	if (verbosity > 0)
1487 		argv[argc++] = (char *)"-v";
1488 	if (verbosity > 1)
1489 		argv[argc++] = (char *)"-v";
1490 	argv[argc++] = NULL;
1491 
1492 	execvp(argv0, argv);
1493 	fatal("execvp");
1494 }
1495 
1496 static void
1497 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1498 {
1499 	struct gotd_child_proc *proc = &gotd.listen_proc;
1500 
1501 	proc->type = PROC_LISTEN;
1502 
1503 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1504 	    PF_UNSPEC, proc->pipe) == -1)
1505 		fatal("socketpair");
1506 
1507 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1508 	    proc->pipe[1], daemonize, verbosity);
1509 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1510 	proc->iev.handler = gotd_dispatch_listener;
1511 	proc->iev.events = EV_READ;
1512 	proc->iev.handler_arg = NULL;
1513 }
1514 
1515 static const struct got_error *
1516 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1517     char *argv0, const char *confpath, int daemonize, int verbosity)
1518 {
1519 	struct gotd_child_proc *proc;
1520 
1521 	proc = calloc(1, sizeof(*proc));
1522 	if (proc == NULL)
1523 		return got_error_from_errno("calloc");
1524 
1525 	proc->type = PROC_SESSION;
1526 	if (strlcpy(proc->repo_name, repo->name,
1527 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1528 		fatalx("repository name too long: %s", repo->name);
1529 	log_debug("starting client uid %d session for repository %s",
1530 	    client->euid, repo->name);
1531 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1532 	    sizeof(proc->repo_path))
1533 		fatalx("repository path too long: %s", repo->path);
1534 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1535 	    PF_UNSPEC, proc->pipe) == -1)
1536 		fatal("socketpair");
1537 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1538 	    confpath, proc->pipe[1], daemonize, verbosity);
1539 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1540 	log_debug("proc %s %s is on fd %d",
1541 	    gotd_proc_names[proc->type], proc->repo_path,
1542 	    proc->pipe[0]);
1543 	proc->iev.handler = gotd_dispatch_client_session;
1544 	proc->iev.events = EV_READ;
1545 	proc->iev.handler_arg = NULL;
1546 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1547 	    gotd_dispatch_client_session, &proc->iev);
1548 	gotd_imsg_event_add(&proc->iev);
1549 
1550 	client->session = proc;
1551 	return NULL;
1552 }
1553 
1554 static const struct got_error *
1555 start_repo_child(struct gotd_client *client, enum gotd_procid proc_type,
1556     struct gotd_repo *repo, char *argv0, const char *confpath,
1557     int daemonize, int verbosity)
1558 {
1559 	struct gotd_child_proc *proc;
1560 
1561 	if (proc_type != PROC_REPO_READ && proc_type != PROC_REPO_WRITE)
1562 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad process type");
1563 
1564 	proc = calloc(1, sizeof(*proc));
1565 	if (proc == NULL)
1566 		return got_error_from_errno("calloc");
1567 
1568 	proc->type = proc_type;
1569 	if (strlcpy(proc->repo_name, repo->name,
1570 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1571 		fatalx("repository name too long: %s", repo->name);
1572 	log_debug("starting %s for repository %s",
1573 	    proc->type == PROC_REPO_READ ? "reader" : "writer", repo->name);
1574 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1575 	    sizeof(proc->repo_path))
1576 		fatalx("repository path too long: %s", repo->path);
1577 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1578 	    PF_UNSPEC, proc->pipe) == -1)
1579 		fatal("socketpair");
1580 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1581 	    confpath, proc->pipe[1], daemonize, verbosity);
1582 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1583 	log_debug("proc %s %s is on fd %d",
1584 	    gotd_proc_names[proc->type], proc->repo_path,
1585 	    proc->pipe[0]);
1586 	proc->iev.handler = gotd_dispatch_repo_child;
1587 	proc->iev.events = EV_READ;
1588 	proc->iev.handler_arg = NULL;
1589 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1590 	    gotd_dispatch_repo_child, &proc->iev);
1591 	gotd_imsg_event_add(&proc->iev);
1592 
1593 	client->repo = proc;
1594 	return NULL;
1595 }
1596 
1597 static const struct got_error *
1598 start_auth_child(struct gotd_client *client, int required_auth,
1599     struct gotd_repo *repo, char *argv0, const char *confpath,
1600     int daemonize, int verbosity)
1601 {
1602 	const struct got_error *err = NULL;
1603 	struct gotd_child_proc *proc;
1604 	struct gotd_imsg_auth iauth;
1605 	int fd;
1606 
1607 	memset(&iauth, 0, sizeof(iauth));
1608 
1609 	fd = dup(client->fd);
1610 	if (fd == -1)
1611 		return got_error_from_errno("dup");
1612 
1613 	proc = calloc(1, sizeof(*proc));
1614 	if (proc == NULL) {
1615 		err = got_error_from_errno("calloc");
1616 		close(fd);
1617 		return err;
1618 	}
1619 
1620 	proc->type = PROC_AUTH;
1621 	if (strlcpy(proc->repo_name, repo->name,
1622 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1623 		fatalx("repository name too long: %s", repo->name);
1624 	log_debug("starting auth for uid %d repository %s",
1625 	    client->euid, repo->name);
1626 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1627 	    sizeof(proc->repo_path))
1628 		fatalx("repository path too long: %s", repo->path);
1629 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1630 	    PF_UNSPEC, proc->pipe) == -1)
1631 		fatal("socketpair");
1632 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1633 	    confpath, proc->pipe[1], daemonize, verbosity);
1634 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1635 	log_debug("proc %s %s is on fd %d",
1636 	    gotd_proc_names[proc->type], proc->repo_path,
1637 	    proc->pipe[0]);
1638 	proc->iev.handler = gotd_dispatch_auth_child;
1639 	proc->iev.events = EV_READ;
1640 	proc->iev.handler_arg = NULL;
1641 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1642 	    gotd_dispatch_auth_child, &proc->iev);
1643 	gotd_imsg_event_add(&proc->iev);
1644 
1645 	iauth.euid = client->euid;
1646 	iauth.egid = client->egid;
1647 	iauth.required_auth = required_auth;
1648 	iauth.client_id = client->id;
1649 	if (gotd_imsg_compose_event(&proc->iev, GOTD_IMSG_AUTHENTICATE,
1650 	    PROC_GOTD, fd, &iauth, sizeof(iauth)) == -1) {
1651 		log_warn("imsg compose AUTHENTICATE");
1652 		close(fd);
1653 		/* Let the auth_timeout handler tidy up. */
1654 	}
1655 
1656 	client->auth = proc;
1657 	client->required_auth = required_auth;
1658 	return NULL;
1659 }
1660 
1661 static void
1662 apply_unveil_repo_readonly(const char *repo_path)
1663 {
1664 	if (unveil(repo_path, "r") == -1)
1665 		fatal("unveil %s", repo_path);
1666 
1667 	if (unveil(NULL, NULL) == -1)
1668 		fatal("unveil");
1669 }
1670 
1671 static void
1672 apply_unveil_repo_readwrite(const char *repo_path)
1673 {
1674 	if (unveil(repo_path, "rwc") == -1)
1675 		fatal("unveil %s", repo_path);
1676 
1677 	if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1678 		fatal("unveil %s", GOT_TMPDIR_STR);
1679 
1680 	if (unveil(NULL, NULL) == -1)
1681 		fatal("unveil");
1682 }
1683 
1684 static void
1685 apply_unveil_none(void)
1686 {
1687 	if (unveil("/", "") == -1)
1688 		fatal("unveil");
1689 
1690 	if (unveil(NULL, NULL) == -1)
1691 		fatal("unveil");
1692 }
1693 
1694 static void
1695 apply_unveil_selfexec(void)
1696 {
1697 	if (unveil(gotd.argv0, "x") == -1)
1698 		fatal("unveil %s", gotd.argv0);
1699 
1700 	if (unveil(NULL, NULL) == -1)
1701 		fatal("unveil");
1702 }
1703 
1704 int
1705 main(int argc, char **argv)
1706 {
1707 	const struct got_error *error = NULL;
1708 	int ch, fd = -1, daemonize = 1, verbosity = 0, noaction = 0;
1709 	const char *confpath = GOTD_CONF_PATH;
1710 	char *argv0 = argv[0];
1711 	char title[2048];
1712 	struct passwd *pw = NULL;
1713 	char *repo_path = NULL;
1714 	enum gotd_procid proc_id = PROC_GOTD;
1715 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1716 	int *pack_fds = NULL, *temp_fds = NULL;
1717 
1718 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1719 
1720 	while ((ch = getopt(argc, argv, "Adf:LnP:RSvW")) != -1) {
1721 		switch (ch) {
1722 		case 'A':
1723 			proc_id = PROC_AUTH;
1724 			break;
1725 		case 'd':
1726 			daemonize = 0;
1727 			break;
1728 		case 'f':
1729 			confpath = optarg;
1730 			break;
1731 		case 'L':
1732 			proc_id = PROC_LISTEN;
1733 			break;
1734 		case 'n':
1735 			noaction = 1;
1736 			break;
1737 		case 'P':
1738 			repo_path = realpath(optarg, NULL);
1739 			if (repo_path == NULL)
1740 				fatal("realpath '%s'", optarg);
1741 			break;
1742 		case 'R':
1743 			proc_id = PROC_REPO_READ;
1744 			break;
1745 		case 'S':
1746 			proc_id = PROC_SESSION;
1747 			break;
1748 		case 'v':
1749 			if (verbosity < 3)
1750 				verbosity++;
1751 			break;
1752 		case 'W':
1753 			proc_id = PROC_REPO_WRITE;
1754 			break;
1755 		default:
1756 			usage();
1757 		}
1758 	}
1759 
1760 	argc -= optind;
1761 	argv += optind;
1762 
1763 	if (argc != 0)
1764 		usage();
1765 
1766 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1767 		fatalx("need root privileges");
1768 
1769 	if (parse_config(confpath, proc_id, &gotd) != 0)
1770 		return 1;
1771 
1772 	pw = getpwnam(gotd.user_name);
1773 	if (pw == NULL)
1774 		fatalx("user %s not found", gotd.user_name);
1775 
1776 	if (pw->pw_uid == 0)
1777 		fatalx("cannot run %s as the superuser", getprogname());
1778 
1779 	if (noaction) {
1780 		fprintf(stderr, "configuration OK\n");
1781 		return 0;
1782 	}
1783 
1784 	gotd.argv0 = argv0;
1785 	gotd.daemonize = daemonize;
1786 	gotd.verbosity = verbosity;
1787 	gotd.confpath = confpath;
1788 
1789 	/* Require an absolute path in argv[0] for reliable re-exec. */
1790 	if (!got_path_is_absolute(argv0))
1791 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1792 
1793 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1794 	log_setverbose(verbosity);
1795 
1796 	if (proc_id == PROC_GOTD) {
1797 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1798 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1799 		if (daemonize && daemon(1, 0) == -1)
1800 			fatal("daemon");
1801 		gotd.pid = getpid();
1802 		start_listener(argv0, confpath, daemonize, verbosity);
1803 	} else if (proc_id == PROC_LISTEN) {
1804 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1805 		if (verbosity) {
1806 			log_info("socket: %s", gotd.unix_socket_path);
1807 			log_info("user: %s", pw->pw_name);
1808 		}
1809 
1810 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1811 		    pw->pw_gid);
1812 		if (fd == -1) {
1813 			fatal("cannot listen on unix socket %s",
1814 			    gotd.unix_socket_path);
1815 		}
1816 	} else if (proc_id == PROC_AUTH) {
1817 		snprintf(title, sizeof(title), "%s %s",
1818 		    gotd_proc_names[proc_id], repo_path);
1819 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1820 	    proc_id == PROC_SESSION) {
1821 		error = got_repo_pack_fds_open(&pack_fds);
1822 		if (error != NULL)
1823 			fatalx("cannot open pack tempfiles: %s", error->msg);
1824 		error = got_repo_temp_fds_open(&temp_fds);
1825 		if (error != NULL)
1826 			fatalx("cannot open pack tempfiles: %s", error->msg);
1827 		if (repo_path == NULL)
1828 			fatalx("repository path not specified");
1829 		snprintf(title, sizeof(title), "%s %s",
1830 		    gotd_proc_names[proc_id], repo_path);
1831 	} else
1832 		fatal("invalid process id %d", proc_id);
1833 
1834 	setproctitle("%s", title);
1835 	log_procinit(title);
1836 
1837 	/* Drop root privileges. */
1838 	if (setgid(pw->pw_gid) == -1)
1839 		fatal("setgid %d failed", pw->pw_gid);
1840 	if (setuid(pw->pw_uid) == -1)
1841 		fatal("setuid %d failed", pw->pw_uid);
1842 
1843 	event_init();
1844 
1845 	switch (proc_id) {
1846 	case PROC_GOTD:
1847 #ifndef PROFILE
1848 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1849 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1850 			err(1, "pledge");
1851 #endif
1852 		break;
1853 	case PROC_LISTEN:
1854 #ifndef PROFILE
1855 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1856 			err(1, "pledge");
1857 #endif
1858 		/*
1859 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1860 		 * sockets by revoking all filesystem access via unveil(2).
1861 		 */
1862 		apply_unveil_none();
1863 
1864 		listen_main(title, fd, gotd.connection_limits,
1865 		    gotd.nconnection_limits);
1866 		/* NOTREACHED */
1867 		break;
1868 	case PROC_AUTH:
1869 #ifndef PROFILE
1870 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1871 			err(1, "pledge");
1872 #endif
1873 		/*
1874 		 * We need the "unix" pledge promise for getpeername(2) only.
1875 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1876 		 * filesystem access via unveil(2). Access to password database
1877 		 * files will still work since "getpw" bypasses unveil(2).
1878 		 */
1879 		apply_unveil_none();
1880 
1881 		auth_main(title, &gotd.repos, repo_path);
1882 		/* NOTREACHED */
1883 		break;
1884 	case PROC_SESSION:
1885 #ifndef PROFILE
1886 		/*
1887 		 * The "recvfd" promise is only needed during setup and
1888 		 * will be removed in a later pledge(2) call.
1889 		 */
1890 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1891 		    "unveil", NULL) == -1)
1892 			err(1, "pledge");
1893 #endif
1894 		apply_unveil_repo_readwrite(repo_path);
1895 		session_main(title, repo_path, pack_fds, temp_fds,
1896 		    &gotd.request_timeout);
1897 		/* NOTREACHED */
1898 		break;
1899 	case PROC_REPO_READ:
1900 #ifndef PROFILE
1901 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1902 			err(1, "pledge");
1903 #endif
1904 		apply_unveil_repo_readonly(repo_path);
1905 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1906 		/* NOTREACHED */
1907 		exit(0);
1908 	case PROC_REPO_WRITE:
1909 #ifndef PROFILE
1910 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1911 			err(1, "pledge");
1912 #endif
1913 		apply_unveil_repo_readonly(repo_path);
1914 		repo_write_main(title, repo_path, pack_fds, temp_fds);
1915 		/* NOTREACHED */
1916 		exit(0);
1917 	default:
1918 		fatal("invalid process id %d", proc_id);
1919 	}
1920 
1921 	if (proc_id != PROC_GOTD)
1922 		fatal("invalid process id %d", proc_id);
1923 
1924 	apply_unveil_selfexec();
1925 
1926 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1927 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1928 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1929 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1930 	signal(SIGPIPE, SIG_IGN);
1931 
1932 	signal_add(&evsigint, NULL);
1933 	signal_add(&evsigterm, NULL);
1934 	signal_add(&evsighup, NULL);
1935 	signal_add(&evsigusr1, NULL);
1936 
1937 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1938 
1939 	event_dispatch();
1940 
1941 	free(repo_path);
1942 	gotd_shutdown();
1943 
1944 	return 0;
1945 }