op public repos

Blob

Date:: Mon May 1 13:09:44 2023 UTC
Message:: gotd: return early after disconnect on auth event error This fixes a segv reported by Mikhail. In this path, any error is already logged, client freed, and event_del() called so we don't need to cleanup in done. ok stsp@
Actions:: History | Blame | Raw File
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/tree.h>
19 #include <sys/time.h>
20 #include <sys/types.h>
21 #include <sys/stat.h>
22 #include <sys/socket.h>
23 #include <sys/un.h>
24 #include <sys/wait.h>
25 
26 #include <fcntl.h>
27 #include <err.h>
28 #include <errno.h>
29 #include <event.h>
30 #include <limits.h>
31 #include <pwd.h>
32 #include <imsg.h>
33 #include <sha1.h>
34 #include <sha2.h>
35 #include <signal.h>
36 #include <siphash.h>
37 #include <stdarg.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <syslog.h>
42 #include <unistd.h>
43 
44 #include "got_error.h"
45 #include "got_opentemp.h"
46 #include "got_path.h"
47 #include "got_repository.h"
48 #include "got_object.h"
49 #include "got_reference.h"
50 
51 #include "got_lib_delta.h"
52 #include "got_lib_object.h"
53 #include "got_lib_object_cache.h"
54 #include "got_lib_hash.h"
55 #include "got_lib_gitproto.h"
56 #include "got_lib_pack.h"
57 #include "got_lib_repository.h"
58 
59 #include "gotd.h"
60 #include "log.h"
61 #include "listen.h"
62 #include "auth.h"
63 #include "session.h"
64 #include "repo_read.h"
65 #include "repo_write.h"
66 
67 #ifndef nitems
68 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
69 #endif
70 
71 enum gotd_client_state {
72 	GOTD_CLIENT_STATE_NEW,
73 	GOTD_CLIENT_STATE_ACCESS_GRANTED,
74 };
75 
76 struct gotd_client {
77 	STAILQ_ENTRY(gotd_client)	 entry;
78 	enum gotd_client_state		 state;
79 	uint32_t			 id;
80 	int				 fd;
81 	struct gotd_imsgev		 iev;
82 	struct event			 tmo;
83 	uid_t				 euid;
84 	gid_t				 egid;
85 	struct gotd_child_proc		*repo;
86 	struct gotd_child_proc		*auth;
87 	struct gotd_child_proc		*session;
88 	int				 required_auth;
89 };
90 STAILQ_HEAD(gotd_clients, gotd_client);
91 
92 static struct gotd_clients gotd_clients[GOTD_CLIENT_TABLE_SIZE];
93 static SIPHASH_KEY clients_hash_key;
94 volatile int client_cnt;
95 static struct timeval auth_timeout = { 5, 0 };
96 static struct gotd gotd;
97 
98 void gotd_sighdlr(int sig, short event, void *arg);
99 static void gotd_shutdown(void);
100 static const struct got_error *start_session_child(struct gotd_client *,
101     struct gotd_repo *, char *, const char *, int, int);
102 static const struct got_error *start_repo_child(struct gotd_client *,
103     enum gotd_procid, struct gotd_repo *, char *, const char *, int, int);
104 static const struct got_error *start_auth_child(struct gotd_client *, int,
105     struct gotd_repo *, char *, const char *, int, int);
106 static void kill_proc(struct gotd_child_proc *, int);
107 
108 __dead static void
109 usage(void)
110 {
111 	fprintf(stderr, "usage: %s [-dnv] [-f config-file]\n", getprogname());
112 	exit(1);
113 }
114 
115 static int
116 unix_socket_listen(const char *unix_socket_path, uid_t uid, gid_t gid)
117 {
118 	struct sockaddr_un sun;
119 	int fd = -1;
120 	mode_t old_umask, mode;
121 
122 	fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
123 	if (fd == -1) {
124 		log_warn("socket");
125 		return -1;
126 	}
127 
128 	sun.sun_family = AF_UNIX;
129 	if (strlcpy(sun.sun_path, unix_socket_path,
130 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
131 		log_warnx("%s: name too long", unix_socket_path);
132 		close(fd);
133 		return -1;
134 	}
135 
136 	if (unlink(unix_socket_path) == -1) {
137 		if (errno != ENOENT) {
138 			log_warn("unlink %s", unix_socket_path);
139 			close(fd);
140 			return -1;
141 		}
142 	}
143 
144 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
145 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
146 
147 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
148 		log_warn("bind: %s", unix_socket_path);
149 		close(fd);
150 		umask(old_umask);
151 		return -1;
152 	}
153 
154 	umask(old_umask);
155 
156 	if (chmod(unix_socket_path, mode) == -1) {
157 		log_warn("chmod %o %s", mode, unix_socket_path);
158 		close(fd);
159 		unlink(unix_socket_path);
160 		return -1;
161 	}
162 
163 	if (chown(unix_socket_path, uid, gid) == -1) {
164 		log_warn("chown %s uid=%d gid=%d", unix_socket_path, uid, gid);
165 		close(fd);
166 		unlink(unix_socket_path);
167 		return -1;
168 	}
169 
170 	if (listen(fd, GOTD_UNIX_SOCKET_BACKLOG) == -1) {
171 		log_warn("listen");
172 		close(fd);
173 		unlink(unix_socket_path);
174 		return -1;
175 	}
176 
177 	return fd;
178 }
179 
180 static uint64_t
181 client_hash(uint32_t client_id)
182 {
183 	return SipHash24(&clients_hash_key, &client_id, sizeof(client_id));
184 }
185 
186 static void
187 add_client(struct gotd_client *client)
188 {
189 	uint64_t slot = client_hash(client->id) % nitems(gotd_clients);
190 	STAILQ_INSERT_HEAD(&gotd_clients[slot], client, entry);
191 	client_cnt++;
192 }
193 
194 static struct gotd_client *
195 find_client(uint32_t client_id)
196 {
197 	uint64_t slot;
198 	struct gotd_client *c;
199 
200 	slot = client_hash(client_id) % nitems(gotd_clients);
201 	STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
202 		if (c->id == client_id)
203 			return c;
204 	}
205 
206 	return NULL;
207 }
208 
209 static struct gotd_client *
210 find_client_by_proc_fd(int fd)
211 {
212 	uint64_t slot;
213 
214 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
215 		struct gotd_client *c;
216 
217 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
218 			if (c->repo && c->repo->iev.ibuf.fd == fd)
219 				return c;
220 			if (c->auth && c->auth->iev.ibuf.fd == fd)
221 				return c;
222 			if (c->session && c->session->iev.ibuf.fd == fd)
223 				return c;
224 		}
225 	}
226 
227 	return NULL;
228 }
229 
230 static int
231 client_is_reading(struct gotd_client *client)
232 {
233 	return (client->required_auth &
234 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) == GOTD_AUTH_READ;
235 }
236 
237 static int
238 client_is_writing(struct gotd_client *client)
239 {
240 	return (client->required_auth &
241 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) ==
242 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE);
243 }
244 
245 static const struct got_error *
246 ensure_client_is_not_writing(struct gotd_client *client)
247 {
248 	if (client_is_writing(client)) {
249 		return got_error_fmt(GOT_ERR_BAD_PACKET,
250 		    "uid %d made a read-request but is writing to "
251 		    "a repository", client->euid);
252 	}
253 
254 	return NULL;
255 }
256 
257 static const struct got_error *
258 ensure_client_is_not_reading(struct gotd_client *client)
259 {
260 	if (client_is_reading(client)) {
261 		return got_error_fmt(GOT_ERR_BAD_PACKET,
262 		    "uid %d made a write-request but is reading from "
263 		    "a repository", client->euid);
264 	}
265 
266 	return NULL;
267 }
268 
269 static void
270 wait_for_child(pid_t child_pid)
271 {
272 	pid_t pid;
273 	int status;
274 
275 	log_debug("waiting for child PID %ld to terminate",
276 	    (long)child_pid);
277 
278 	do {
279 		pid = waitpid(child_pid, &status, WNOHANG);
280 		if (pid == -1) {
281 			if (errno != EINTR && errno != ECHILD)
282 				fatal("wait");
283 		} else if (WIFSIGNALED(status)) {
284 			log_warnx("child PID %ld terminated; signal %d",
285 			    (long)pid, WTERMSIG(status));
286 		}
287 	} while (pid != -1 || (pid == -1 && errno == EINTR));
288 }
289 
290 static void
291 proc_done(struct gotd_child_proc *proc)
292 {
293 	event_del(&proc->iev.ev);
294 	msgbuf_clear(&proc->iev.ibuf.w);
295 	close(proc->iev.ibuf.fd);
296 	kill_proc(proc, 0);
297 	wait_for_child(proc->pid);
298 	free(proc);
299 }
300 
301 static void
302 kill_auth_proc(struct gotd_client *client)
303 {
304 	struct gotd_child_proc *proc;
305 
306 	if (client->auth == NULL)
307 		return;
308 
309 	proc = client->auth;
310 	client->auth = NULL;
311 
312 	proc_done(proc);
313 }
314 
315 static void
316 kill_session_proc(struct gotd_client *client)
317 {
318 	struct gotd_child_proc *proc;
319 
320 	if (client->session == NULL)
321 		return;
322 
323 	proc = client->session;
324 	client->session = NULL;
325 
326 	proc_done(proc);
327 }
328 
329 static void
330 disconnect(struct gotd_client *client)
331 {
332 	struct gotd_imsg_disconnect idisconnect;
333 	struct gotd_child_proc *proc = client->repo;
334 	struct gotd_child_proc *listen_proc = &gotd.listen_proc;
335 	uint64_t slot;
336 
337 	log_debug("uid %d: disconnecting", client->euid);
338 
339 	kill_auth_proc(client);
340 	kill_session_proc(client);
341 
342 	if (proc) {
343 		event_del(&proc->iev.ev);
344 		msgbuf_clear(&proc->iev.ibuf.w);
345 		close(proc->iev.ibuf.fd);
346 		kill_proc(proc, 0);
347 		wait_for_child(proc->pid);
348 		free(proc);
349 		proc = NULL;
350 	}
351 
352 	idisconnect.client_id = client->id;
353 	if (gotd_imsg_compose_event(&listen_proc->iev,
354 	    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
355 	    &idisconnect, sizeof(idisconnect)) == -1)
356 		log_warn("imsg compose DISCONNECT");
357 
358 	slot = client_hash(client->id) % nitems(gotd_clients);
359 	STAILQ_REMOVE(&gotd_clients[slot], client, gotd_client, entry);
360 	imsg_clear(&client->iev.ibuf);
361 	event_del(&client->iev.ev);
362 	evtimer_del(&client->tmo);
363 	if (client->fd != -1)
364 		close(client->fd);
365 	else if (client->iev.ibuf.fd != -1)
366 		close(client->iev.ibuf.fd);
367 	free(client);
368 	client_cnt--;
369 }
370 
371 static void
372 disconnect_on_error(struct gotd_client *client, const struct got_error *err)
373 {
374 	struct imsgbuf ibuf;
375 
376 	log_warnx("uid %d: %s", client->euid, err->msg);
377 	if (err->code != GOT_ERR_EOF && client->fd != -1) {
378 		imsg_init(&ibuf, client->fd);
379 		gotd_imsg_send_error(&ibuf, 0, PROC_GOTD, err);
380 		imsg_clear(&ibuf);
381 	}
382 	disconnect(client);
383 }
384 
385 static const struct got_error *
386 send_repo_info(struct gotd_imsgev *iev, struct gotd_repo *repo)
387 {
388 	const struct got_error *err = NULL;
389 	struct gotd_imsg_info_repo irepo;
390 
391 	memset(&irepo, 0, sizeof(irepo));
392 
393 	if (strlcpy(irepo.repo_name, repo->name, sizeof(irepo.repo_name))
394 	    >= sizeof(irepo.repo_name))
395 		return got_error_msg(GOT_ERR_NO_SPACE, "repo name too long");
396 	if (strlcpy(irepo.repo_path, repo->path, sizeof(irepo.repo_path))
397 	    >= sizeof(irepo.repo_path))
398 		return got_error_msg(GOT_ERR_NO_SPACE, "repo path too long");
399 
400 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_REPO, PROC_GOTD, -1,
401 	    &irepo, sizeof(irepo)) == -1) {
402 		err = got_error_from_errno("imsg compose INFO_REPO");
403 		if (err)
404 			return err;
405 	}
406 
407 	return NULL;
408 }
409 
410 static const struct got_error *
411 send_client_info(struct gotd_imsgev *iev, struct gotd_client *client)
412 {
413 	const struct got_error *err = NULL;
414 	struct gotd_imsg_info_client iclient;
415 	struct gotd_child_proc *proc;
416 
417 	memset(&iclient, 0, sizeof(iclient));
418 	iclient.euid = client->euid;
419 	iclient.egid = client->egid;
420 
421 	proc = client->repo;
422 	if (proc) {
423 		if (strlcpy(iclient.repo_name, proc->repo_path,
424 		    sizeof(iclient.repo_name)) >= sizeof(iclient.repo_name)) {
425 			return got_error_msg(GOT_ERR_NO_SPACE,
426 			    "repo name too long");
427 		}
428 		if (client_is_writing(client))
429 			iclient.is_writing = 1;
430 
431 		iclient.repo_child_pid = proc->pid;
432 	}
433 
434 	if (client->session)
435 		iclient.session_child_pid = client->session->pid;
436 
437 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_CLIENT, PROC_GOTD, -1,
438 	    &iclient, sizeof(iclient)) == -1) {
439 		err = got_error_from_errno("imsg compose INFO_CLIENT");
440 		if (err)
441 			return err;
442 	}
443 
444 	return NULL;
445 }
446 
447 static const struct got_error *
448 send_info(struct gotd_client *client)
449 {
450 	const struct got_error *err = NULL;
451 	struct gotd_imsg_info info;
452 	uint64_t slot;
453 	struct gotd_repo *repo;
454 
455 	if (client->euid != 0)
456 		return got_error_set_errno(EPERM, "info");
457 
458 	info.pid = gotd.pid;
459 	info.verbosity = gotd.verbosity;
460 	info.nrepos = gotd.nrepos;
461 	info.nclients = client_cnt - 1;
462 
463 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_INFO, PROC_GOTD, -1,
464 	    &info, sizeof(info)) == -1) {
465 		err = got_error_from_errno("imsg compose INFO");
466 		if (err)
467 			return err;
468 	}
469 
470 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
471 		err = send_repo_info(&client->iev, repo);
472 		if (err)
473 			return err;
474 	}
475 
476 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
477 		struct gotd_client *c;
478 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
479 			if (c->id == client->id)
480 				continue;
481 			err = send_client_info(&client->iev, c);
482 			if (err)
483 				return err;
484 		}
485 	}
486 
487 	return NULL;
488 }
489 
490 static const struct got_error *
491 stop_gotd(struct gotd_client *client)
492 {
493 
494 	if (client->euid != 0)
495 		return got_error_set_errno(EPERM, "stop");
496 
497 	gotd_shutdown();
498 	/* NOTREACHED */
499 	return NULL;
500 }
501 
502 static const struct got_error *
503 start_client_authentication(struct gotd_client *client, struct imsg *imsg)
504 {
505 	const struct got_error *err;
506 	struct gotd_imsg_list_refs ireq;
507 	struct gotd_repo *repo = NULL;
508 	size_t datalen;
509 
510 	log_debug("list-refs request from uid %d", client->euid);
511 
512 	if (client->state != GOTD_CLIENT_STATE_NEW)
513 		return got_error_msg(GOT_ERR_BAD_REQUEST,
514 		    "unexpected list-refs request received");
515 
516 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
517 	if (datalen != sizeof(ireq))
518 		return got_error(GOT_ERR_PRIVSEP_LEN);
519 
520 	memcpy(&ireq, imsg->data, datalen);
521 
522 	if (ireq.client_is_reading) {
523 		err = ensure_client_is_not_writing(client);
524 		if (err)
525 			return err;
526 		repo = gotd_find_repo_by_name(ireq.repo_name, &gotd);
527 		if (repo == NULL)
528 			return got_error(GOT_ERR_NOT_GIT_REPO);
529 		err = start_auth_child(client, GOTD_AUTH_READ, repo,
530 		    gotd.argv0, gotd.confpath, gotd.daemonize,
531 		    gotd.verbosity);
532 		if (err)
533 			return err;
534 	} else {
535 		err = ensure_client_is_not_reading(client);
536 		if (err)
537 			return err;
538 		repo = gotd_find_repo_by_name(ireq.repo_name, &gotd);
539 		if (repo == NULL)
540 			return got_error(GOT_ERR_NOT_GIT_REPO);
541 		err = start_auth_child(client,
542 		    GOTD_AUTH_READ | GOTD_AUTH_WRITE,
543 		    repo, gotd.argv0, gotd.confpath, gotd.daemonize,
544 		    gotd.verbosity);
545 		if (err)
546 			return err;
547 	}
548 
549 	evtimer_add(&client->tmo, &auth_timeout);
550 
551 	/* Flow continues upon authentication successs/failure or timeout. */
552 	return NULL;
553 }
554 
555 static void
556 gotd_request(int fd, short events, void *arg)
557 {
558 	struct gotd_imsgev *iev = arg;
559 	struct imsgbuf *ibuf = &iev->ibuf;
560 	struct gotd_client *client = iev->handler_arg;
561 	const struct got_error *err = NULL;
562 	struct imsg imsg;
563 	ssize_t n;
564 
565 	if (events & EV_WRITE) {
566 		while (ibuf->w.queued) {
567 			n = msgbuf_write(&ibuf->w);
568 			if (n == -1 && errno == EPIPE) {
569 				/*
570 				 * The client has closed its socket.
571 				 * This can happen when Git clients are
572 				 * done sending pack file data.
573 				 */
574 				msgbuf_clear(&ibuf->w);
575 				continue;
576 			} else if (n == -1 && errno != EAGAIN) {
577 				err = got_error_from_errno("imsg_flush");
578 				disconnect_on_error(client, err);
579 				return;
580 			}
581 			if (n == 0) {
582 				/* Connection closed. */
583 				err = got_error(GOT_ERR_EOF);
584 				disconnect_on_error(client, err);
585 				return;
586 			}
587 		}
588 
589 		/* Disconnect gotctl(8) now that messages have been sent. */
590 		if (!client_is_reading(client) && !client_is_writing(client)) {
591 			disconnect(client);
592 			return;
593 		}
594 	}
595 
596 	if ((events & EV_READ) == 0)
597 		return;
598 
599 	memset(&imsg, 0, sizeof(imsg));
600 
601 	while (err == NULL) {
602 		err = gotd_imsg_recv(&imsg, ibuf, 0);
603 		if (err) {
604 			if (err->code == GOT_ERR_PRIVSEP_READ)
605 				err = NULL;
606 			break;
607 		}
608 
609 		evtimer_del(&client->tmo);
610 
611 		switch (imsg.hdr.type) {
612 		case GOTD_IMSG_INFO:
613 			err = send_info(client);
614 			break;
615 		case GOTD_IMSG_STOP:
616 			err = stop_gotd(client);
617 			break;
618 		case GOTD_IMSG_LIST_REFS:
619 			err = start_client_authentication(client, &imsg);
620 			break;
621 		default:
622 			log_debug("unexpected imsg %d", imsg.hdr.type);
623 			err = got_error(GOT_ERR_PRIVSEP_MSG);
624 			break;
625 		}
626 
627 		imsg_free(&imsg);
628 	}
629 
630 	if (err) {
631 		disconnect_on_error(client, err);
632 	} else {
633 		gotd_imsg_event_add(&client->iev);
634 	}
635 }
636 
637 static void
638 gotd_auth_timeout(int fd, short events, void *arg)
639 {
640 	struct gotd_client *client = arg;
641 
642 	log_debug("disconnecting uid %d due to authentication timeout",
643 	    client->euid);
644 	disconnect(client);
645 }
646 
647 static const struct got_error *
648 recv_connect(uint32_t *client_id, struct imsg *imsg)
649 {
650 	const struct got_error *err = NULL;
651 	struct gotd_imsg_connect iconnect;
652 	size_t datalen;
653 	int s = -1;
654 	struct gotd_client *client = NULL;
655 
656 	*client_id = 0;
657 
658 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
659 	if (datalen != sizeof(iconnect))
660 		return got_error(GOT_ERR_PRIVSEP_LEN);
661 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
662 
663 	s = imsg->fd;
664 	if (s == -1) {
665 		err = got_error(GOT_ERR_PRIVSEP_NO_FD);
666 		goto done;
667 	}
668 
669 	if (find_client(iconnect.client_id)) {
670 		err = got_error_msg(GOT_ERR_CLIENT_ID, "duplicate client ID");
671 		goto done;
672 	}
673 
674 	client = calloc(1, sizeof(*client));
675 	if (client == NULL) {
676 		err = got_error_from_errno("calloc");
677 		goto done;
678 	}
679 
680 	*client_id = iconnect.client_id;
681 
682 	client->state = GOTD_CLIENT_STATE_NEW;
683 	client->id = iconnect.client_id;
684 	client->fd = s;
685 	s = -1;
686 	/* The auth process will verify UID/GID for us. */
687 	client->euid = iconnect.euid;
688 	client->egid = iconnect.egid;
689 
690 	imsg_init(&client->iev.ibuf, client->fd);
691 	client->iev.handler = gotd_request;
692 	client->iev.events = EV_READ;
693 	client->iev.handler_arg = client;
694 
695 	event_set(&client->iev.ev, client->fd, EV_READ, gotd_request,
696 	    &client->iev);
697 	gotd_imsg_event_add(&client->iev);
698 
699 	evtimer_set(&client->tmo, gotd_auth_timeout, client);
700 
701 	add_client(client);
702 	log_debug("%s: new client uid %d connected on fd %d", __func__,
703 	    client->euid, client->fd);
704 done:
705 	if (err) {
706 		struct gotd_child_proc *listen_proc = &gotd.listen_proc;
707 		struct gotd_imsg_disconnect idisconnect;
708 
709 		idisconnect.client_id = client->id;
710 		if (gotd_imsg_compose_event(&listen_proc->iev,
711 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
712 		    &idisconnect, sizeof(idisconnect)) == -1)
713 			log_warn("imsg compose DISCONNECT");
714 
715 		if (s != -1)
716 			close(s);
717 	}
718 
719 	return err;
720 }
721 
722 static const char *gotd_proc_names[PROC_MAX] = {
723 	"parent",
724 	"listen",
725 	"auth",
726 	"session",
727 	"repo_read",
728 	"repo_write"
729 };
730 
731 static void
732 kill_proc(struct gotd_child_proc *proc, int fatal)
733 {
734 	if (fatal) {
735 		log_warnx("sending SIGKILL to PID %d", proc->pid);
736 		kill(proc->pid, SIGKILL);
737 	} else
738 		kill(proc->pid, SIGTERM);
739 }
740 
741 static void
742 gotd_shutdown(void)
743 {
744 	struct gotd_child_proc *proc;
745 	uint64_t slot;
746 
747 	log_debug("shutting down");
748 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
749 		struct gotd_client *c, *tmp;
750 
751 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
752 			disconnect(c);
753 	}
754 
755 	proc = &gotd.listen_proc;
756 	msgbuf_clear(&proc->iev.ibuf.w);
757 	close(proc->iev.ibuf.fd);
758 	kill_proc(proc, 0);
759 	wait_for_child(proc->pid);
760 
761 	log_info("terminating");
762 	exit(0);
763 }
764 
765 void
766 gotd_sighdlr(int sig, short event, void *arg)
767 {
768 	/*
769 	 * Normal signal handler rules don't apply because libevent
770 	 * decouples for us.
771 	 */
772 
773 	switch (sig) {
774 	case SIGHUP:
775 		log_info("%s: ignoring SIGHUP", __func__);
776 		break;
777 	case SIGUSR1:
778 		log_info("%s: ignoring SIGUSR1", __func__);
779 		break;
780 	case SIGTERM:
781 	case SIGINT:
782 		gotd_shutdown();
783 		break;
784 	default:
785 		fatalx("unexpected signal");
786 	}
787 }
788 
789 static const struct got_error *
790 ensure_proc_is_reading(struct gotd_client *client,
791     struct gotd_child_proc *proc)
792 {
793 	if (!client_is_reading(client)) {
794 		kill_proc(proc, 1);
795 		return got_error_fmt(GOT_ERR_BAD_PACKET,
796 		    "PID %d handled a read-request for uid %d but this "
797 		    "user is not reading from a repository", proc->pid,
798 		    client->euid);
799 	}
800 
801 	return NULL;
802 }
803 
804 static const struct got_error *
805 ensure_proc_is_writing(struct gotd_client *client,
806     struct gotd_child_proc *proc)
807 {
808 	if (!client_is_writing(client)) {
809 		kill_proc(proc, 1);
810 		return got_error_fmt(GOT_ERR_BAD_PACKET,
811 		    "PID %d handled a write-request for uid %d but this "
812 		    "user is not writing to a repository", proc->pid,
813 		    client->euid);
814 	}
815 
816 	return NULL;
817 }
818 
819 static int
820 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
821     struct imsg *imsg)
822 {
823 	const struct got_error *err;
824 	int ret = 0;
825 
826 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
827 		if (client->repo == NULL)
828 			fatalx("no process found for uid %d", client->euid);
829 		if (proc->pid != client->repo->pid) {
830 			kill_proc(proc, 1);
831 			log_warnx("received message from PID %d for uid %d, "
832 			    "while PID %d is the process serving this user",
833 			    proc->pid, client->euid, client->repo->pid);
834 			return 0;
835 		}
836 	}
837 	if (proc->type == PROC_SESSION) {
838 		if (client->session == NULL) {
839 			log_warnx("no session found for uid %d", client->euid);
840 			return 0;
841 		}
842 		if (proc->pid != client->session->pid) {
843 			kill_proc(proc, 1);
844 			log_warnx("received message from PID %d for uid %d, "
845 			    "while PID %d is the process serving this user",
846 			    proc->pid, client->euid, client->session->pid);
847 			return 0;
848 		}
849 	}
850 
851 	switch (imsg->hdr.type) {
852 	case GOTD_IMSG_ERROR:
853 		ret = 1;
854 		break;
855 	case GOTD_IMSG_CONNECT:
856 		if (proc->type != PROC_LISTEN) {
857 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
858 			    "new connection for uid %d from PID %d "
859 			    "which is not the listen process",
860 			    proc->pid, client->euid);
861 		} else
862 			ret = 1;
863 		break;
864 	case GOTD_IMSG_ACCESS_GRANTED:
865 		if (proc->type != PROC_AUTH) {
866 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
867 			    "authentication of uid %d from PID %d "
868 			    "which is not the auth process",
869 			    proc->pid, client->euid);
870 		} else
871 			ret = 1;
872 		break;
873 	case GOTD_IMSG_CLIENT_SESSION_READY:
874 		if (proc->type != PROC_SESSION) {
875 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
876 			    "unexpected \"ready\" signal from PID %d",
877 			    proc->pid);
878 		} else
879 			ret = 1;
880 		break;
881 	case GOTD_IMSG_REPO_CHILD_READY:
882 		if (proc->type != PROC_REPO_READ &&
883 		    proc->type != PROC_REPO_WRITE) {
884 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
885 			    "unexpected \"ready\" signal from PID %d",
886 			    proc->pid);
887 		} else
888 			ret = 1;
889 		break;
890 	case GOTD_IMSG_PACKFILE_DONE:
891 		err = ensure_proc_is_reading(client, proc);
892 		if (err)
893 			log_warnx("uid %d: %s", client->euid, err->msg);
894 		else
895 			ret = 1;
896 		break;
897 	case GOTD_IMSG_PACKFILE_INSTALL:
898 	case GOTD_IMSG_REF_UPDATES_START:
899 	case GOTD_IMSG_REF_UPDATE:
900 		err = ensure_proc_is_writing(client, proc);
901 		if (err)
902 			log_warnx("uid %d: %s", client->euid, err->msg);
903 		else
904 			ret = 1;
905 		break;
906 	default:
907 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
908 		break;
909 	}
910 
911 	return ret;
912 }
913 
914 static const struct got_error *
915 connect_repo_child(struct gotd_client *client,
916     struct gotd_child_proc *repo_proc)
917 {
918 	static const struct got_error *err;
919 	struct gotd_imsgev *session_iev = &client->session->iev;
920 	struct gotd_imsg_connect_repo_child ireq;
921 	int pipe[2];
922 
923 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
924 		return got_error_msg(GOT_ERR_BAD_REQUEST,
925 		    "unexpected repo child ready signal received");
926 
927 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
928 	    PF_UNSPEC, pipe) == -1)
929 		fatal("socketpair");
930 
931 	memset(&ireq, 0, sizeof(ireq));
932 	ireq.client_id = client->id;
933 	ireq.proc_id = repo_proc->type;
934 
935 	/* Pass repo child pipe to session child process. */
936 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
937 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
938 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
939 		close(pipe[0]);
940 		close(pipe[1]);
941 		return err;
942 	}
943 
944 	/* Pass session child pipe to repo child process. */
945 	if (gotd_imsg_compose_event(&repo_proc->iev,
946 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
947 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
948 		close(pipe[1]);
949 		return err;
950 	}
951 
952 	return NULL;
953 }
954 
955 static void
956 gotd_dispatch_listener(int fd, short event, void *arg)
957 {
958 	struct gotd_imsgev *iev = arg;
959 	struct imsgbuf *ibuf = &iev->ibuf;
960 	struct gotd_child_proc *proc = &gotd.listen_proc;
961 	ssize_t n;
962 	int shut = 0;
963 	struct imsg imsg;
964 
965 	if (proc->iev.ibuf.fd != fd)
966 		fatalx("%s: unexpected fd %d", __func__, fd);
967 
968 	if (event & EV_READ) {
969 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
970 			fatal("imsg_read error");
971 		if (n == 0) {
972 			/* Connection closed. */
973 			shut = 1;
974 			goto done;
975 		}
976 	}
977 
978 	if (event & EV_WRITE) {
979 		n = msgbuf_write(&ibuf->w);
980 		if (n == -1 && errno != EAGAIN)
981 			fatal("msgbuf_write");
982 		if (n == 0) {
983 			/* Connection closed. */
984 			shut = 1;
985 			goto done;
986 		}
987 	}
988 
989 	for (;;) {
990 		const struct got_error *err = NULL;
991 		struct gotd_client *client = NULL;
992 		uint32_t client_id = 0;
993 		int do_disconnect = 0;
994 
995 		if ((n = imsg_get(ibuf, &imsg)) == -1)
996 			fatal("%s: imsg_get error", __func__);
997 		if (n == 0)	/* No more messages. */
998 			break;
999 
1000 		switch (imsg.hdr.type) {
1001 		case GOTD_IMSG_ERROR:
1002 			do_disconnect = 1;
1003 			err = gotd_imsg_recv_error(&client_id, &imsg);
1004 			break;
1005 		case GOTD_IMSG_CONNECT:
1006 			err = recv_connect(&client_id, &imsg);
1007 			break;
1008 		default:
1009 			log_debug("unexpected imsg %d", imsg.hdr.type);
1010 			break;
1011 		}
1012 
1013 		client = find_client(client_id);
1014 		if (client == NULL) {
1015 			log_warnx("%s: client not found", __func__);
1016 			imsg_free(&imsg);
1017 			continue;
1018 		}
1019 
1020 		if (err)
1021 			log_warnx("uid %d: %s", client->euid, err->msg);
1022 
1023 		if (do_disconnect) {
1024 			if (err)
1025 				disconnect_on_error(client, err);
1026 			else
1027 				disconnect(client);
1028 		}
1029 
1030 		imsg_free(&imsg);
1031 	}
1032 done:
1033 	if (!shut) {
1034 		gotd_imsg_event_add(iev);
1035 	} else {
1036 		/* This pipe is dead. Remove its event handler */
1037 		event_del(&iev->ev);
1038 		event_loopexit(NULL);
1039 	}
1040 }
1041 
1042 static void
1043 gotd_dispatch_auth_child(int fd, short event, void *arg)
1044 {
1045 	const struct got_error *err = NULL;
1046 	struct gotd_imsgev *iev = arg;
1047 	struct imsgbuf *ibuf = &iev->ibuf;
1048 	struct gotd_client *client;
1049 	struct gotd_repo *repo = NULL;
1050 	ssize_t n;
1051 	int shut = 0;
1052 	struct imsg imsg;
1053 	uint32_t client_id = 0;
1054 	int do_disconnect = 0;
1055 
1056 	client = find_client_by_proc_fd(fd);
1057 	if (client == NULL) {
1058 		/* Can happen during process teardown. */
1059 		warnx("cannot find client for fd %d", fd);
1060 		shut = 1;
1061 		goto done;
1062 	}
1063 
1064 	if (client->auth == NULL)
1065 		fatalx("cannot find auth child process for fd %d", fd);
1066 
1067 	if (event & EV_READ) {
1068 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1069 			fatal("imsg_read error");
1070 		if (n == 0) {
1071 			/* Connection closed. */
1072 			shut = 1;
1073 			goto done;
1074 		}
1075 	}
1076 
1077 	if (event & EV_WRITE) {
1078 		n = msgbuf_write(&ibuf->w);
1079 		if (n == -1 && errno != EAGAIN)
1080 			fatal("msgbuf_write");
1081 		if (n == 0) {
1082 			/* Connection closed. */
1083 			shut = 1;
1084 		}
1085 		goto done;
1086 	}
1087 
1088 	if (client->auth->iev.ibuf.fd != fd)
1089 		fatalx("%s: unexpected fd %d", __func__, fd);
1090 
1091 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1092 		fatal("%s: imsg_get error", __func__);
1093 	if (n == 0)	/* No more messages. */
1094 		return;
1095 
1096 	evtimer_del(&client->tmo);
1097 
1098 	switch (imsg.hdr.type) {
1099 	case GOTD_IMSG_ERROR:
1100 		do_disconnect = 1;
1101 		err = gotd_imsg_recv_error(&client_id, &imsg);
1102 		break;
1103 	case GOTD_IMSG_ACCESS_GRANTED:
1104 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1105 		break;
1106 	default:
1107 		do_disconnect = 1;
1108 		log_debug("unexpected imsg %d", imsg.hdr.type);
1109 		break;
1110 	}
1111 
1112 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1113 		do_disconnect = 1;
1114 		log_debug("dropping imsg type %d from PID %d",
1115 		    imsg.hdr.type, client->auth->pid);
1116 	}
1117 	imsg_free(&imsg);
1118 
1119 	if (do_disconnect) {
1120 		if (err)
1121 			disconnect_on_error(client, err);
1122 		else
1123 			disconnect(client);
1124 		return;
1125 	}
1126 
1127 	repo = gotd_find_repo_by_name(client->auth->repo_name, &gotd);
1128 	if (repo == NULL) {
1129 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1130 		goto done;
1131 	}
1132 	kill_auth_proc(client);
1133 
1134 	log_info("authenticated uid %d for repository %s",
1135 	    client->euid, repo->name);
1136 
1137 	err = start_session_child(client, repo, gotd.argv0,
1138 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1139 	if (err)
1140 		goto done;
1141 done:
1142 	if (err)
1143 		log_warnx("uid %d: %s", client->euid, err->msg);
1144 
1145 	/* We might have killed the auth process by now. */
1146 	if (client->auth != NULL) {
1147 		if (!shut) {
1148 			gotd_imsg_event_add(iev);
1149 		} else {
1150 			/* This pipe is dead. Remove its event handler */
1151 			event_del(&iev->ev);
1152 		}
1153 	}
1154 }
1155 
1156 static const struct got_error *
1157 connect_session(struct gotd_client *client)
1158 {
1159 	const struct got_error *err = NULL;
1160 	struct gotd_imsg_connect iconnect;
1161 	int s;
1162 
1163 	memset(&iconnect, 0, sizeof(iconnect));
1164 
1165 	s = dup(client->fd);
1166 	if (s == -1)
1167 		return got_error_from_errno("dup");
1168 
1169 	iconnect.client_id = client->id;
1170 	iconnect.euid = client->euid;
1171 	iconnect.egid = client->egid;
1172 
1173 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1174 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1175 		err = got_error_from_errno("imsg compose CONNECT");
1176 		close(s);
1177 		return err;
1178 	}
1179 
1180 	/*
1181 	 * We are no longer interested in messages from this client.
1182 	 * Further client requests will be handled by the session process.
1183 	 */
1184 	msgbuf_clear(&client->iev.ibuf.w);
1185 	imsg_clear(&client->iev.ibuf);
1186 	event_del(&client->iev.ev);
1187 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1188 
1189 	return NULL;
1190 }
1191 
1192 static void
1193 gotd_dispatch_client_session(int fd, short event, void *arg)
1194 {
1195 	struct gotd_imsgev *iev = arg;
1196 	struct imsgbuf *ibuf = &iev->ibuf;
1197 	struct gotd_child_proc *proc = NULL;
1198 	struct gotd_client *client = NULL;
1199 	ssize_t n;
1200 	int shut = 0;
1201 	struct imsg imsg;
1202 
1203 	client = find_client_by_proc_fd(fd);
1204 	if (client == NULL) {
1205 		/* Can happen during process teardown. */
1206 		warnx("cannot find client for fd %d", fd);
1207 		shut = 1;
1208 		goto done;
1209 	}
1210 
1211 	if (event & EV_READ) {
1212 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1213 			fatal("imsg_read error");
1214 		if (n == 0) {
1215 			/* Connection closed. */
1216 			shut = 1;
1217 			goto done;
1218 		}
1219 	}
1220 
1221 	if (event & EV_WRITE) {
1222 		n = msgbuf_write(&ibuf->w);
1223 		if (n == -1 && errno != EAGAIN)
1224 			fatal("msgbuf_write");
1225 		if (n == 0) {
1226 			/* Connection closed. */
1227 			shut = 1;
1228 			goto done;
1229 		}
1230 	}
1231 
1232 	proc = client->session;
1233 	if (proc == NULL)
1234 		fatalx("cannot find session child process for fd %d", fd);
1235 
1236 	for (;;) {
1237 		const struct got_error *err = NULL;
1238 		uint32_t client_id = 0;
1239 		int do_disconnect = 0, do_start_repo_child = 0;
1240 
1241 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1242 			fatal("%s: imsg_get error", __func__);
1243 		if (n == 0)	/* No more messages. */
1244 			break;
1245 
1246 		switch (imsg.hdr.type) {
1247 		case GOTD_IMSG_ERROR:
1248 			do_disconnect = 1;
1249 			err = gotd_imsg_recv_error(&client_id, &imsg);
1250 			break;
1251 		case GOTD_IMSG_CLIENT_SESSION_READY:
1252 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1253 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1254 				break;
1255 			}
1256 			do_start_repo_child = 1;
1257 			break;
1258 		case GOTD_IMSG_DISCONNECT:
1259 			do_disconnect = 1;
1260 			break;
1261 		default:
1262 			log_debug("unexpected imsg %d", imsg.hdr.type);
1263 			break;
1264 		}
1265 
1266 		if (!verify_imsg_src(client, proc, &imsg)) {
1267 			log_debug("dropping imsg type %d from PID %d",
1268 			    imsg.hdr.type, proc->pid);
1269 			imsg_free(&imsg);
1270 			continue;
1271 		}
1272 		if (err)
1273 			log_warnx("uid %d: %s", client->euid, err->msg);
1274 
1275 		if (do_start_repo_child) {
1276 			struct gotd_repo *repo;
1277 			const char *name = client->session->repo_name;
1278 
1279 			repo = gotd_find_repo_by_name(name, &gotd);
1280 			if (repo != NULL) {
1281 				enum gotd_procid proc_type;
1282 
1283 				if (client->required_auth & GOTD_AUTH_WRITE)
1284 					proc_type = PROC_REPO_WRITE;
1285 				else
1286 					proc_type = PROC_REPO_READ;
1287 
1288 				err = start_repo_child(client, proc_type, repo,
1289 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1290 				    gotd.verbosity);
1291 			} else
1292 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1293 
1294 			if (err) {
1295 				log_warnx("uid %d: %s", client->euid, err->msg);
1296 				do_disconnect = 1;
1297 			}
1298 		}
1299 
1300 		if (do_disconnect) {
1301 			if (err)
1302 				disconnect_on_error(client, err);
1303 			else
1304 				disconnect(client);
1305 		}
1306 
1307 		imsg_free(&imsg);
1308 	}
1309 done:
1310 	if (!shut) {
1311 		gotd_imsg_event_add(iev);
1312 	} else {
1313 		/* This pipe is dead. Remove its event handler */
1314 		event_del(&iev->ev);
1315 		disconnect(client);
1316 	}
1317 }
1318 
1319 static void
1320 gotd_dispatch_repo_child(int fd, short event, void *arg)
1321 {
1322 	struct gotd_imsgev *iev = arg;
1323 	struct imsgbuf *ibuf = &iev->ibuf;
1324 	struct gotd_child_proc *proc = NULL;
1325 	struct gotd_client *client;
1326 	ssize_t n;
1327 	int shut = 0;
1328 	struct imsg imsg;
1329 
1330 	client = find_client_by_proc_fd(fd);
1331 	if (client == NULL) {
1332 		/* Can happen during process teardown. */
1333 		warnx("cannot find client for fd %d", fd);
1334 		shut = 1;
1335 		goto done;
1336 	}
1337 
1338 	if (event & EV_READ) {
1339 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1340 			fatal("imsg_read error");
1341 		if (n == 0) {
1342 			/* Connection closed. */
1343 			shut = 1;
1344 			goto done;
1345 		}
1346 	}
1347 
1348 	if (event & EV_WRITE) {
1349 		n = msgbuf_write(&ibuf->w);
1350 		if (n == -1 && errno != EAGAIN)
1351 			fatal("msgbuf_write");
1352 		if (n == 0) {
1353 			/* Connection closed. */
1354 			shut = 1;
1355 			goto done;
1356 		}
1357 	}
1358 
1359 	proc = client->repo;
1360 	if (proc == NULL)
1361 		fatalx("cannot find child process for fd %d", fd);
1362 
1363 	for (;;) {
1364 		const struct got_error *err = NULL;
1365 		uint32_t client_id = 0;
1366 		int do_disconnect = 0;
1367 
1368 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1369 			fatal("%s: imsg_get error", __func__);
1370 		if (n == 0)	/* No more messages. */
1371 			break;
1372 
1373 		switch (imsg.hdr.type) {
1374 		case GOTD_IMSG_ERROR:
1375 			do_disconnect = 1;
1376 			err = gotd_imsg_recv_error(&client_id, &imsg);
1377 			break;
1378 		case GOTD_IMSG_REPO_CHILD_READY:
1379 			err = connect_session(client);
1380 			if (err)
1381 				break;
1382 			err = connect_repo_child(client, proc);
1383 			break;
1384 		default:
1385 			log_debug("unexpected imsg %d", imsg.hdr.type);
1386 			break;
1387 		}
1388 
1389 		if (!verify_imsg_src(client, proc, &imsg)) {
1390 			log_debug("dropping imsg type %d from PID %d",
1391 			    imsg.hdr.type, proc->pid);
1392 			imsg_free(&imsg);
1393 			continue;
1394 		}
1395 		if (err)
1396 			log_warnx("uid %d: %s", client->euid, err->msg);
1397 
1398 		if (do_disconnect) {
1399 			if (err)
1400 				disconnect_on_error(client, err);
1401 			else
1402 				disconnect(client);
1403 		}
1404 
1405 		imsg_free(&imsg);
1406 	}
1407 done:
1408 	if (!shut) {
1409 		gotd_imsg_event_add(iev);
1410 	} else {
1411 		/* This pipe is dead. Remove its event handler */
1412 		event_del(&iev->ev);
1413 		disconnect(client);
1414 	}
1415 }
1416 
1417 static pid_t
1418 start_child(enum gotd_procid proc_id, const char *repo_path,
1419     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1420 {
1421 	char	*argv[11];
1422 	int	 argc = 0;
1423 	pid_t	 pid;
1424 
1425 	switch (pid = fork()) {
1426 	case -1:
1427 		fatal("cannot fork");
1428 	case 0:
1429 		break;
1430 	default:
1431 		close(fd);
1432 		return pid;
1433 	}
1434 
1435 	if (fd != GOTD_FILENO_MSG_PIPE) {
1436 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1437 			fatal("cannot setup imsg fd");
1438 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1439 		fatal("cannot setup imsg fd");
1440 
1441 	argv[argc++] = argv0;
1442 	switch (proc_id) {
1443 	case PROC_LISTEN:
1444 		argv[argc++] = (char *)"-L";
1445 		break;
1446 	case PROC_AUTH:
1447 		argv[argc++] = (char *)"-A";
1448 		break;
1449 	case PROC_SESSION:
1450 		argv[argc++] = (char *)"-S";
1451 		break;
1452 	case PROC_REPO_READ:
1453 		argv[argc++] = (char *)"-R";
1454 		break;
1455 	case PROC_REPO_WRITE:
1456 		argv[argc++] = (char *)"-W";
1457 		break;
1458 	default:
1459 		fatalx("invalid process id %d", proc_id);
1460 	}
1461 
1462 	argv[argc++] = (char *)"-f";
1463 	argv[argc++] = (char *)confpath;
1464 
1465 	if (repo_path) {
1466 		argv[argc++] = (char *)"-P";
1467 		argv[argc++] = (char *)repo_path;
1468 	}
1469 
1470 	if (!daemonize)
1471 		argv[argc++] = (char *)"-d";
1472 	if (verbosity > 0)
1473 		argv[argc++] = (char *)"-v";
1474 	if (verbosity > 1)
1475 		argv[argc++] = (char *)"-v";
1476 	argv[argc++] = NULL;
1477 
1478 	execvp(argv0, argv);
1479 	fatal("execvp");
1480 }
1481 
1482 static void
1483 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1484 {
1485 	struct gotd_child_proc *proc = &gotd.listen_proc;
1486 
1487 	proc->type = PROC_LISTEN;
1488 
1489 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1490 	    PF_UNSPEC, proc->pipe) == -1)
1491 		fatal("socketpair");
1492 
1493 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1494 	    proc->pipe[1], daemonize, verbosity);
1495 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1496 	proc->iev.handler = gotd_dispatch_listener;
1497 	proc->iev.events = EV_READ;
1498 	proc->iev.handler_arg = NULL;
1499 }
1500 
1501 static const struct got_error *
1502 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1503     char *argv0, const char *confpath, int daemonize, int verbosity)
1504 {
1505 	struct gotd_child_proc *proc;
1506 
1507 	proc = calloc(1, sizeof(*proc));
1508 	if (proc == NULL)
1509 		return got_error_from_errno("calloc");
1510 
1511 	proc->type = PROC_SESSION;
1512 	if (strlcpy(proc->repo_name, repo->name,
1513 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1514 		fatalx("repository name too long: %s", repo->name);
1515 	log_debug("starting client uid %d session for repository %s",
1516 	    client->euid, repo->name);
1517 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1518 	    sizeof(proc->repo_path))
1519 		fatalx("repository path too long: %s", repo->path);
1520 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1521 	    PF_UNSPEC, proc->pipe) == -1)
1522 		fatal("socketpair");
1523 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1524 	    confpath, proc->pipe[1], daemonize, verbosity);
1525 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1526 	log_debug("proc %s %s is on fd %d",
1527 	    gotd_proc_names[proc->type], proc->repo_path,
1528 	    proc->pipe[0]);
1529 	proc->iev.handler = gotd_dispatch_client_session;
1530 	proc->iev.events = EV_READ;
1531 	proc->iev.handler_arg = NULL;
1532 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1533 	    gotd_dispatch_client_session, &proc->iev);
1534 	gotd_imsg_event_add(&proc->iev);
1535 
1536 	client->session = proc;
1537 	return NULL;
1538 }
1539 
1540 static const struct got_error *
1541 start_repo_child(struct gotd_client *client, enum gotd_procid proc_type,
1542     struct gotd_repo *repo, char *argv0, const char *confpath,
1543     int daemonize, int verbosity)
1544 {
1545 	struct gotd_child_proc *proc;
1546 
1547 	if (proc_type != PROC_REPO_READ && proc_type != PROC_REPO_WRITE)
1548 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad process type");
1549 
1550 	proc = calloc(1, sizeof(*proc));
1551 	if (proc == NULL)
1552 		return got_error_from_errno("calloc");
1553 
1554 	proc->type = proc_type;
1555 	if (strlcpy(proc->repo_name, repo->name,
1556 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1557 		fatalx("repository name too long: %s", repo->name);
1558 	log_debug("starting %s for repository %s",
1559 	    proc->type == PROC_REPO_READ ? "reader" : "writer", repo->name);
1560 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1561 	    sizeof(proc->repo_path))
1562 		fatalx("repository path too long: %s", repo->path);
1563 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1564 	    PF_UNSPEC, proc->pipe) == -1)
1565 		fatal("socketpair");
1566 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1567 	    confpath, proc->pipe[1], daemonize, verbosity);
1568 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1569 	log_debug("proc %s %s is on fd %d",
1570 	    gotd_proc_names[proc->type], proc->repo_path,
1571 	    proc->pipe[0]);
1572 	proc->iev.handler = gotd_dispatch_repo_child;
1573 	proc->iev.events = EV_READ;
1574 	proc->iev.handler_arg = NULL;
1575 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1576 	    gotd_dispatch_repo_child, &proc->iev);
1577 	gotd_imsg_event_add(&proc->iev);
1578 
1579 	client->repo = proc;
1580 	return NULL;
1581 }
1582 
1583 static const struct got_error *
1584 start_auth_child(struct gotd_client *client, int required_auth,
1585     struct gotd_repo *repo, char *argv0, const char *confpath,
1586     int daemonize, int verbosity)
1587 {
1588 	const struct got_error *err = NULL;
1589 	struct gotd_child_proc *proc;
1590 	struct gotd_imsg_auth iauth;
1591 	int fd;
1592 
1593 	memset(&iauth, 0, sizeof(iauth));
1594 
1595 	fd = dup(client->fd);
1596 	if (fd == -1)
1597 		return got_error_from_errno("dup");
1598 
1599 	proc = calloc(1, sizeof(*proc));
1600 	if (proc == NULL) {
1601 		err = got_error_from_errno("calloc");
1602 		close(fd);
1603 		return err;
1604 	}
1605 
1606 	proc->type = PROC_AUTH;
1607 	if (strlcpy(proc->repo_name, repo->name,
1608 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1609 		fatalx("repository name too long: %s", repo->name);
1610 	log_debug("starting auth for uid %d repository %s",
1611 	    client->euid, repo->name);
1612 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1613 	    sizeof(proc->repo_path))
1614 		fatalx("repository path too long: %s", repo->path);
1615 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1616 	    PF_UNSPEC, proc->pipe) == -1)
1617 		fatal("socketpair");
1618 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1619 	    confpath, proc->pipe[1], daemonize, verbosity);
1620 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1621 	log_debug("proc %s %s is on fd %d",
1622 	    gotd_proc_names[proc->type], proc->repo_path,
1623 	    proc->pipe[0]);
1624 	proc->iev.handler = gotd_dispatch_auth_child;
1625 	proc->iev.events = EV_READ;
1626 	proc->iev.handler_arg = NULL;
1627 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1628 	    gotd_dispatch_auth_child, &proc->iev);
1629 	gotd_imsg_event_add(&proc->iev);
1630 
1631 	iauth.euid = client->euid;
1632 	iauth.egid = client->egid;
1633 	iauth.required_auth = required_auth;
1634 	iauth.client_id = client->id;
1635 	if (gotd_imsg_compose_event(&proc->iev, GOTD_IMSG_AUTHENTICATE,
1636 	    PROC_GOTD, fd, &iauth, sizeof(iauth)) == -1) {
1637 		log_warn("imsg compose AUTHENTICATE");
1638 		close(fd);
1639 		/* Let the auth_timeout handler tidy up. */
1640 	}
1641 
1642 	client->auth = proc;
1643 	client->required_auth = required_auth;
1644 	return NULL;
1645 }
1646 
1647 static void
1648 apply_unveil_repo_readonly(const char *repo_path)
1649 {
1650 	if (unveil(repo_path, "r") == -1)
1651 		fatal("unveil %s", repo_path);
1652 
1653 	if (unveil(NULL, NULL) == -1)
1654 		fatal("unveil");
1655 }
1656 
1657 static void
1658 apply_unveil_repo_readwrite(const char *repo_path)
1659 {
1660 	if (unveil(repo_path, "rwc") == -1)
1661 		fatal("unveil %s", repo_path);
1662 
1663 	if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1664 		fatal("unveil %s", GOT_TMPDIR_STR);
1665 
1666 	if (unveil(NULL, NULL) == -1)
1667 		fatal("unveil");
1668 }
1669 
1670 static void
1671 apply_unveil_none(void)
1672 {
1673 	if (unveil("/", "") == -1)
1674 		fatal("unveil");
1675 
1676 	if (unveil(NULL, NULL) == -1)
1677 		fatal("unveil");
1678 }
1679 
1680 static void
1681 apply_unveil_selfexec(void)
1682 {
1683 	if (unveil(gotd.argv0, "x") == -1)
1684 		fatal("unveil %s", gotd.argv0);
1685 
1686 	if (unveil(NULL, NULL) == -1)
1687 		fatal("unveil");
1688 }
1689 
1690 int
1691 main(int argc, char **argv)
1692 {
1693 	const struct got_error *error = NULL;
1694 	int ch, fd = -1, daemonize = 1, verbosity = 0, noaction = 0;
1695 	const char *confpath = GOTD_CONF_PATH;
1696 	char *argv0 = argv[0];
1697 	char title[2048];
1698 	struct passwd *pw = NULL;
1699 	char *repo_path = NULL;
1700 	enum gotd_procid proc_id = PROC_GOTD;
1701 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1702 	int *pack_fds = NULL, *temp_fds = NULL;
1703 	struct gotd_repo *repo = NULL;
1704 
1705 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1706 
1707 	while ((ch = getopt(argc, argv, "Adf:LnP:RSvW")) != -1) {
1708 		switch (ch) {
1709 		case 'A':
1710 			proc_id = PROC_AUTH;
1711 			break;
1712 		case 'd':
1713 			daemonize = 0;
1714 			break;
1715 		case 'f':
1716 			confpath = optarg;
1717 			break;
1718 		case 'L':
1719 			proc_id = PROC_LISTEN;
1720 			break;
1721 		case 'n':
1722 			noaction = 1;
1723 			break;
1724 		case 'P':
1725 			repo_path = realpath(optarg, NULL);
1726 			if (repo_path == NULL)
1727 				fatal("realpath '%s'", optarg);
1728 			break;
1729 		case 'R':
1730 			proc_id = PROC_REPO_READ;
1731 			break;
1732 		case 'S':
1733 			proc_id = PROC_SESSION;
1734 			break;
1735 		case 'v':
1736 			if (verbosity < 3)
1737 				verbosity++;
1738 			break;
1739 		case 'W':
1740 			proc_id = PROC_REPO_WRITE;
1741 			break;
1742 		default:
1743 			usage();
1744 		}
1745 	}
1746 
1747 	argc -= optind;
1748 	argv += optind;
1749 
1750 	if (argc != 0)
1751 		usage();
1752 
1753 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1754 		fatalx("need root privileges");
1755 
1756 	if (parse_config(confpath, proc_id, &gotd, 1) != 0)
1757 		return 1;
1758 
1759 	pw = getpwnam(gotd.user_name);
1760 	if (pw == NULL)
1761 		fatalx("user %s not found", gotd.user_name);
1762 
1763 	if (pw->pw_uid == 0)
1764 		fatalx("cannot run %s as the superuser", getprogname());
1765 
1766 	if (noaction) {
1767 		fprintf(stderr, "configuration OK\n");
1768 		return 0;
1769 	}
1770 
1771 	gotd.argv0 = argv0;
1772 	gotd.daemonize = daemonize;
1773 	gotd.verbosity = verbosity;
1774 	gotd.confpath = confpath;
1775 
1776 	/* Require an absolute path in argv[0] for reliable re-exec. */
1777 	if (!got_path_is_absolute(argv0))
1778 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1779 
1780 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1781 	log_setverbose(verbosity);
1782 
1783 	if (proc_id == PROC_GOTD) {
1784 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1785 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1786 		if (daemonize && daemon(1, 0) == -1)
1787 			fatal("daemon");
1788 		gotd.pid = getpid();
1789 		start_listener(argv0, confpath, daemonize, verbosity);
1790 	} else if (proc_id == PROC_LISTEN) {
1791 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1792 		if (verbosity) {
1793 			log_info("socket: %s", gotd.unix_socket_path);
1794 			log_info("user: %s", pw->pw_name);
1795 		}
1796 
1797 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1798 		    pw->pw_gid);
1799 		if (fd == -1) {
1800 			fatal("cannot listen on unix socket %s",
1801 			    gotd.unix_socket_path);
1802 		}
1803 	} else if (proc_id == PROC_AUTH) {
1804 		snprintf(title, sizeof(title), "%s %s",
1805 		    gotd_proc_names[proc_id], repo_path);
1806 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1807 	    proc_id == PROC_SESSION) {
1808 		error = got_repo_pack_fds_open(&pack_fds);
1809 		if (error != NULL)
1810 			fatalx("cannot open pack tempfiles: %s", error->msg);
1811 		error = got_repo_temp_fds_open(&temp_fds);
1812 		if (error != NULL)
1813 			fatalx("cannot open pack tempfiles: %s", error->msg);
1814 		if (repo_path == NULL)
1815 			fatalx("repository path not specified");
1816 		snprintf(title, sizeof(title), "%s %s",
1817 		    gotd_proc_names[proc_id], repo_path);
1818 	} else
1819 		fatal("invalid process id %d", proc_id);
1820 
1821 	setproctitle("%s", title);
1822 	log_procinit(title);
1823 
1824 	/* Drop root privileges. */
1825 	if (setgid(pw->pw_gid) == -1)
1826 		fatal("setgid %d failed", pw->pw_gid);
1827 	if (setuid(pw->pw_uid) == -1)
1828 		fatal("setuid %d failed", pw->pw_uid);
1829 
1830 	event_init();
1831 
1832 	switch (proc_id) {
1833 	case PROC_GOTD:
1834 #ifndef PROFILE
1835 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1836 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1837 			err(1, "pledge");
1838 #endif
1839 		break;
1840 	case PROC_LISTEN:
1841 #ifndef PROFILE
1842 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1843 			err(1, "pledge");
1844 #endif
1845 		/*
1846 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1847 		 * sockets by revoking all filesystem access via unveil(2).
1848 		 */
1849 		apply_unveil_none();
1850 
1851 		listen_main(title, fd, gotd.connection_limits,
1852 		    gotd.nconnection_limits);
1853 		/* NOTREACHED */
1854 		break;
1855 	case PROC_AUTH:
1856 #ifndef PROFILE
1857 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1858 			err(1, "pledge");
1859 #endif
1860 		/*
1861 		 * We need the "unix" pledge promise for getpeername(2) only.
1862 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1863 		 * filesystem access via unveil(2). Access to password database
1864 		 * files will still work since "getpw" bypasses unveil(2).
1865 		 */
1866 		apply_unveil_none();
1867 
1868 		auth_main(title, &gotd.repos, repo_path);
1869 		/* NOTREACHED */
1870 		break;
1871 	case PROC_SESSION:
1872 #ifndef PROFILE
1873 		/*
1874 		 * The "recvfd" promise is only needed during setup and
1875 		 * will be removed in a later pledge(2) call.
1876 		 */
1877 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1878 		    "unveil", NULL) == -1)
1879 			err(1, "pledge");
1880 #endif
1881 		apply_unveil_repo_readwrite(repo_path);
1882 		session_main(title, repo_path, pack_fds, temp_fds,
1883 		    &gotd.request_timeout);
1884 		/* NOTREACHED */
1885 		break;
1886 	case PROC_REPO_READ:
1887 #ifndef PROFILE
1888 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1889 			err(1, "pledge");
1890 #endif
1891 		apply_unveil_repo_readonly(repo_path);
1892 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1893 		/* NOTREACHED */
1894 		exit(0);
1895 	case PROC_REPO_WRITE:
1896 #ifndef PROFILE
1897 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1898 			err(1, "pledge");
1899 #endif
1900 		apply_unveil_repo_readonly(repo_path);
1901 		repo = gotd_find_repo_by_path(repo_path, &gotd);
1902 		if (repo == NULL)
1903 			fatalx("no repository for path %s", repo_path);
1904 		repo_write_main(title, repo_path, pack_fds, temp_fds,
1905 		    &repo->protected_tag_namespaces,
1906 		    &repo->protected_branch_namespaces,
1907 		    &repo->protected_branches);
1908 		/* NOTREACHED */
1909 		exit(0);
1910 	default:
1911 		fatal("invalid process id %d", proc_id);
1912 	}
1913 
1914 	if (proc_id != PROC_GOTD)
1915 		fatal("invalid process id %d", proc_id);
1916 
1917 	apply_unveil_selfexec();
1918 
1919 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1920 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1921 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1922 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1923 	signal(SIGPIPE, SIG_IGN);
1924 
1925 	signal_add(&evsigint, NULL);
1926 	signal_add(&evsigterm, NULL);
1927 	signal_add(&evsighup, NULL);
1928 	signal_add(&evsigusr1, NULL);
1929 
1930 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1931 
1932 	event_dispatch();
1933 
1934 	free(repo_path);
1935 	gotd_shutdown();
1936 
1937 	return 0;
1938 }