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Date:: Mon Jun 19 20:36:49 2023 UTC
Message:: update gotd_proc_names after session process unveil changes fixes "proc (null)" appearing in gotd logs
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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_read",
727 	"session_write",
728 	"repo_read",
729 	"repo_write"
730 };
731 
732 static void
733 kill_proc(struct gotd_child_proc *proc, int fatal)
734 {
735 	if (fatal) {
736 		log_warnx("sending SIGKILL to PID %d", proc->pid);
737 		kill(proc->pid, SIGKILL);
738 	} else
739 		kill(proc->pid, SIGTERM);
740 }
741 
742 static void
743 gotd_shutdown(void)
744 {
745 	struct gotd_child_proc *proc;
746 	uint64_t slot;
747 
748 	log_debug("shutting down");
749 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
750 		struct gotd_client *c, *tmp;
751 
752 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
753 			disconnect(c);
754 	}
755 
756 	proc = &gotd.listen_proc;
757 	msgbuf_clear(&proc->iev.ibuf.w);
758 	close(proc->iev.ibuf.fd);
759 	kill_proc(proc, 0);
760 	wait_for_child(proc->pid);
761 
762 	log_info("terminating");
763 	exit(0);
764 }
765 
766 void
767 gotd_sighdlr(int sig, short event, void *arg)
768 {
769 	/*
770 	 * Normal signal handler rules don't apply because libevent
771 	 * decouples for us.
772 	 */
773 
774 	switch (sig) {
775 	case SIGHUP:
776 		log_info("%s: ignoring SIGHUP", __func__);
777 		break;
778 	case SIGUSR1:
779 		log_info("%s: ignoring SIGUSR1", __func__);
780 		break;
781 	case SIGTERM:
782 	case SIGINT:
783 		gotd_shutdown();
784 		break;
785 	default:
786 		fatalx("unexpected signal");
787 	}
788 }
789 
790 static const struct got_error *
791 ensure_proc_is_reading(struct gotd_client *client,
792     struct gotd_child_proc *proc)
793 {
794 	if (!client_is_reading(client)) {
795 		kill_proc(proc, 1);
796 		return got_error_fmt(GOT_ERR_BAD_PACKET,
797 		    "PID %d handled a read-request for uid %d but this "
798 		    "user is not reading from a repository", proc->pid,
799 		    client->euid);
800 	}
801 
802 	return NULL;
803 }
804 
805 static const struct got_error *
806 ensure_proc_is_writing(struct gotd_client *client,
807     struct gotd_child_proc *proc)
808 {
809 	if (!client_is_writing(client)) {
810 		kill_proc(proc, 1);
811 		return got_error_fmt(GOT_ERR_BAD_PACKET,
812 		    "PID %d handled a write-request for uid %d but this "
813 		    "user is not writing to a repository", proc->pid,
814 		    client->euid);
815 	}
816 
817 	return NULL;
818 }
819 
820 static int
821 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
822     struct imsg *imsg)
823 {
824 	const struct got_error *err;
825 	int ret = 0;
826 
827 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
828 		if (client->repo == NULL)
829 			fatalx("no process found for uid %d", client->euid);
830 		if (proc->pid != client->repo->pid) {
831 			kill_proc(proc, 1);
832 			log_warnx("received message from PID %d for uid %d, "
833 			    "while PID %d is the process serving this user",
834 			    proc->pid, client->euid, client->repo->pid);
835 			return 0;
836 		}
837 	}
838 	if (proc->type == PROC_SESSION_READ ||
839 	    proc->type == PROC_SESSION_WRITE) {
840 		if (client->session == NULL) {
841 			log_warnx("no session found for uid %d", client->euid);
842 			return 0;
843 		}
844 		if (proc->pid != client->session->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->session->pid);
849 			return 0;
850 		}
851 	}
852 
853 	switch (imsg->hdr.type) {
854 	case GOTD_IMSG_ERROR:
855 		ret = 1;
856 		break;
857 	case GOTD_IMSG_CONNECT:
858 		if (proc->type != PROC_LISTEN) {
859 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
860 			    "new connection for uid %d from PID %d "
861 			    "which is not the listen process",
862 			    proc->pid, client->euid);
863 		} else
864 			ret = 1;
865 		break;
866 	case GOTD_IMSG_ACCESS_GRANTED:
867 		if (proc->type != PROC_AUTH) {
868 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
869 			    "authentication of uid %d from PID %d "
870 			    "which is not the auth process",
871 			    proc->pid, client->euid);
872 		} else
873 			ret = 1;
874 		break;
875 	case GOTD_IMSG_CLIENT_SESSION_READY:
876 		if (proc->type != PROC_SESSION_READ &&
877 		    proc->type != PROC_SESSION_WRITE) {
878 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
879 			    "unexpected \"ready\" signal from PID %d",
880 			    proc->pid);
881 		} else
882 			ret = 1;
883 		break;
884 	case GOTD_IMSG_REPO_CHILD_READY:
885 		if (proc->type != PROC_REPO_READ &&
886 		    proc->type != PROC_REPO_WRITE) {
887 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
888 			    "unexpected \"ready\" signal from PID %d",
889 			    proc->pid);
890 		} else
891 			ret = 1;
892 		break;
893 	case GOTD_IMSG_PACKFILE_DONE:
894 		err = ensure_proc_is_reading(client, proc);
895 		if (err)
896 			log_warnx("uid %d: %s", client->euid, err->msg);
897 		else
898 			ret = 1;
899 		break;
900 	case GOTD_IMSG_PACKFILE_INSTALL:
901 	case GOTD_IMSG_REF_UPDATES_START:
902 	case GOTD_IMSG_REF_UPDATE:
903 		err = ensure_proc_is_writing(client, proc);
904 		if (err)
905 			log_warnx("uid %d: %s", client->euid, err->msg);
906 		else
907 			ret = 1;
908 		break;
909 	default:
910 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
911 		break;
912 	}
913 
914 	return ret;
915 }
916 
917 static const struct got_error *
918 connect_repo_child(struct gotd_client *client,
919     struct gotd_child_proc *repo_proc)
920 {
921 	static const struct got_error *err;
922 	struct gotd_imsgev *session_iev = &client->session->iev;
923 	struct gotd_imsg_connect_repo_child ireq;
924 	int pipe[2];
925 
926 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
927 		return got_error_msg(GOT_ERR_BAD_REQUEST,
928 		    "unexpected repo child ready signal received");
929 
930 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
931 	    PF_UNSPEC, pipe) == -1)
932 		fatal("socketpair");
933 
934 	memset(&ireq, 0, sizeof(ireq));
935 	ireq.client_id = client->id;
936 	ireq.proc_id = repo_proc->type;
937 
938 	/* Pass repo child pipe to session child process. */
939 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
940 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
941 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
942 		close(pipe[0]);
943 		close(pipe[1]);
944 		return err;
945 	}
946 
947 	/* Pass session child pipe to repo child process. */
948 	if (gotd_imsg_compose_event(&repo_proc->iev,
949 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
950 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
951 		close(pipe[1]);
952 		return err;
953 	}
954 
955 	return NULL;
956 }
957 
958 static void
959 gotd_dispatch_listener(int fd, short event, void *arg)
960 {
961 	struct gotd_imsgev *iev = arg;
962 	struct imsgbuf *ibuf = &iev->ibuf;
963 	struct gotd_child_proc *proc = &gotd.listen_proc;
964 	ssize_t n;
965 	int shut = 0;
966 	struct imsg imsg;
967 
968 	if (proc->iev.ibuf.fd != fd)
969 		fatalx("%s: unexpected fd %d", __func__, fd);
970 
971 	if (event & EV_READ) {
972 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
973 			fatal("imsg_read error");
974 		if (n == 0) {
975 			/* Connection closed. */
976 			shut = 1;
977 			goto done;
978 		}
979 	}
980 
981 	if (event & EV_WRITE) {
982 		n = msgbuf_write(&ibuf->w);
983 		if (n == -1 && errno != EAGAIN)
984 			fatal("msgbuf_write");
985 		if (n == 0) {
986 			/* Connection closed. */
987 			shut = 1;
988 			goto done;
989 		}
990 	}
991 
992 	for (;;) {
993 		const struct got_error *err = NULL;
994 		struct gotd_client *client = NULL;
995 		uint32_t client_id = 0;
996 		int do_disconnect = 0;
997 
998 		if ((n = imsg_get(ibuf, &imsg)) == -1)
999 			fatal("%s: imsg_get error", __func__);
1000 		if (n == 0)	/* No more messages. */
1001 			break;
1002 
1003 		switch (imsg.hdr.type) {
1004 		case GOTD_IMSG_ERROR:
1005 			do_disconnect = 1;
1006 			err = gotd_imsg_recv_error(&client_id, &imsg);
1007 			break;
1008 		case GOTD_IMSG_CONNECT:
1009 			err = recv_connect(&client_id, &imsg);
1010 			break;
1011 		default:
1012 			log_debug("unexpected imsg %d", imsg.hdr.type);
1013 			break;
1014 		}
1015 
1016 		client = find_client(client_id);
1017 		if (client == NULL) {
1018 			log_warnx("%s: client not found", __func__);
1019 			imsg_free(&imsg);
1020 			continue;
1021 		}
1022 
1023 		if (err)
1024 			log_warnx("uid %d: %s", client->euid, err->msg);
1025 
1026 		if (do_disconnect) {
1027 			if (err)
1028 				disconnect_on_error(client, err);
1029 			else
1030 				disconnect(client);
1031 		}
1032 
1033 		imsg_free(&imsg);
1034 	}
1035 done:
1036 	if (!shut) {
1037 		gotd_imsg_event_add(iev);
1038 	} else {
1039 		/* This pipe is dead. Remove its event handler */
1040 		event_del(&iev->ev);
1041 		event_loopexit(NULL);
1042 	}
1043 }
1044 
1045 static void
1046 gotd_dispatch_auth_child(int fd, short event, void *arg)
1047 {
1048 	const struct got_error *err = NULL;
1049 	struct gotd_imsgev *iev = arg;
1050 	struct imsgbuf *ibuf = &iev->ibuf;
1051 	struct gotd_client *client;
1052 	struct gotd_repo *repo = NULL;
1053 	ssize_t n;
1054 	int shut = 0;
1055 	struct imsg imsg;
1056 	uint32_t client_id = 0;
1057 	int do_disconnect = 0;
1058 
1059 	client = find_client_by_proc_fd(fd);
1060 	if (client == NULL) {
1061 		/* Can happen during process teardown. */
1062 		warnx("cannot find client for fd %d", fd);
1063 		shut = 1;
1064 		goto done;
1065 	}
1066 
1067 	if (client->auth == NULL)
1068 		fatalx("cannot find auth child process for fd %d", fd);
1069 
1070 	if (event & EV_READ) {
1071 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1072 			fatal("imsg_read error");
1073 		if (n == 0) {
1074 			/* Connection closed. */
1075 			shut = 1;
1076 			goto done;
1077 		}
1078 	}
1079 
1080 	if (event & EV_WRITE) {
1081 		n = msgbuf_write(&ibuf->w);
1082 		if (n == -1 && errno != EAGAIN)
1083 			fatal("msgbuf_write");
1084 		if (n == 0) {
1085 			/* Connection closed. */
1086 			shut = 1;
1087 		}
1088 		goto done;
1089 	}
1090 
1091 	if (client->auth->iev.ibuf.fd != fd)
1092 		fatalx("%s: unexpected fd %d", __func__, fd);
1093 
1094 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1095 		fatal("%s: imsg_get error", __func__);
1096 	if (n == 0)	/* No more messages. */
1097 		return;
1098 
1099 	evtimer_del(&client->tmo);
1100 
1101 	switch (imsg.hdr.type) {
1102 	case GOTD_IMSG_ERROR:
1103 		do_disconnect = 1;
1104 		err = gotd_imsg_recv_error(&client_id, &imsg);
1105 		break;
1106 	case GOTD_IMSG_ACCESS_GRANTED:
1107 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1108 		break;
1109 	default:
1110 		do_disconnect = 1;
1111 		log_debug("unexpected imsg %d", imsg.hdr.type);
1112 		break;
1113 	}
1114 
1115 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1116 		do_disconnect = 1;
1117 		log_debug("dropping imsg type %d from PID %d",
1118 		    imsg.hdr.type, client->auth->pid);
1119 	}
1120 	imsg_free(&imsg);
1121 
1122 	if (do_disconnect) {
1123 		if (err)
1124 			disconnect_on_error(client, err);
1125 		else
1126 			disconnect(client);
1127 		return;
1128 	}
1129 
1130 	repo = gotd_find_repo_by_name(client->auth->repo_name, &gotd);
1131 	if (repo == NULL) {
1132 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1133 		goto done;
1134 	}
1135 	kill_auth_proc(client);
1136 
1137 	log_info("authenticated uid %d for repository %s",
1138 	    client->euid, repo->name);
1139 
1140 	err = start_session_child(client, repo, gotd.argv0,
1141 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1142 	if (err)
1143 		goto done;
1144 done:
1145 	if (err)
1146 		log_warnx("uid %d: %s", client->euid, err->msg);
1147 
1148 	/* We might have killed the auth process by now. */
1149 	if (client->auth != NULL) {
1150 		if (!shut) {
1151 			gotd_imsg_event_add(iev);
1152 		} else {
1153 			/* This pipe is dead. Remove its event handler */
1154 			event_del(&iev->ev);
1155 		}
1156 	}
1157 }
1158 
1159 static const struct got_error *
1160 connect_session(struct gotd_client *client)
1161 {
1162 	const struct got_error *err = NULL;
1163 	struct gotd_imsg_connect iconnect;
1164 	int s;
1165 
1166 	memset(&iconnect, 0, sizeof(iconnect));
1167 
1168 	s = dup(client->fd);
1169 	if (s == -1)
1170 		return got_error_from_errno("dup");
1171 
1172 	iconnect.client_id = client->id;
1173 	iconnect.euid = client->euid;
1174 	iconnect.egid = client->egid;
1175 
1176 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1177 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1178 		err = got_error_from_errno("imsg compose CONNECT");
1179 		close(s);
1180 		return err;
1181 	}
1182 
1183 	/*
1184 	 * We are no longer interested in messages from this client.
1185 	 * Further client requests will be handled by the session process.
1186 	 */
1187 	msgbuf_clear(&client->iev.ibuf.w);
1188 	imsg_clear(&client->iev.ibuf);
1189 	event_del(&client->iev.ev);
1190 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1191 
1192 	return NULL;
1193 }
1194 
1195 static void
1196 gotd_dispatch_client_session(int fd, short event, void *arg)
1197 {
1198 	struct gotd_imsgev *iev = arg;
1199 	struct imsgbuf *ibuf = &iev->ibuf;
1200 	struct gotd_child_proc *proc = NULL;
1201 	struct gotd_client *client = NULL;
1202 	ssize_t n;
1203 	int shut = 0;
1204 	struct imsg imsg;
1205 
1206 	client = find_client_by_proc_fd(fd);
1207 	if (client == NULL) {
1208 		/* Can happen during process teardown. */
1209 		warnx("cannot find client for fd %d", fd);
1210 		shut = 1;
1211 		goto done;
1212 	}
1213 
1214 	if (event & EV_READ) {
1215 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1216 			fatal("imsg_read error");
1217 		if (n == 0) {
1218 			/* Connection closed. */
1219 			shut = 1;
1220 			goto done;
1221 		}
1222 	}
1223 
1224 	if (event & EV_WRITE) {
1225 		n = msgbuf_write(&ibuf->w);
1226 		if (n == -1 && errno != EAGAIN)
1227 			fatal("msgbuf_write");
1228 		if (n == 0) {
1229 			/* Connection closed. */
1230 			shut = 1;
1231 			goto done;
1232 		}
1233 	}
1234 
1235 	proc = client->session;
1236 	if (proc == NULL)
1237 		fatalx("cannot find session child process for fd %d", fd);
1238 
1239 	for (;;) {
1240 		const struct got_error *err = NULL;
1241 		uint32_t client_id = 0;
1242 		int do_disconnect = 0, do_start_repo_child = 0;
1243 
1244 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1245 			fatal("%s: imsg_get error", __func__);
1246 		if (n == 0)	/* No more messages. */
1247 			break;
1248 
1249 		switch (imsg.hdr.type) {
1250 		case GOTD_IMSG_ERROR:
1251 			do_disconnect = 1;
1252 			err = gotd_imsg_recv_error(&client_id, &imsg);
1253 			break;
1254 		case GOTD_IMSG_CLIENT_SESSION_READY:
1255 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1256 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1257 				break;
1258 			}
1259 			do_start_repo_child = 1;
1260 			break;
1261 		case GOTD_IMSG_DISCONNECT:
1262 			do_disconnect = 1;
1263 			break;
1264 		default:
1265 			log_debug("unexpected imsg %d", imsg.hdr.type);
1266 			break;
1267 		}
1268 
1269 		if (!verify_imsg_src(client, proc, &imsg)) {
1270 			log_debug("dropping imsg type %d from PID %d",
1271 			    imsg.hdr.type, proc->pid);
1272 			imsg_free(&imsg);
1273 			continue;
1274 		}
1275 		if (err)
1276 			log_warnx("uid %d: %s", client->euid, err->msg);
1277 
1278 		if (do_start_repo_child) {
1279 			struct gotd_repo *repo;
1280 			const char *name = client->session->repo_name;
1281 
1282 			repo = gotd_find_repo_by_name(name, &gotd);
1283 			if (repo != NULL) {
1284 				enum gotd_procid proc_type;
1285 
1286 				if (client->required_auth & GOTD_AUTH_WRITE)
1287 					proc_type = PROC_REPO_WRITE;
1288 				else
1289 					proc_type = PROC_REPO_READ;
1290 
1291 				err = start_repo_child(client, proc_type, repo,
1292 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1293 				    gotd.verbosity);
1294 			} else
1295 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1296 
1297 			if (err) {
1298 				log_warnx("uid %d: %s", client->euid, err->msg);
1299 				do_disconnect = 1;
1300 			}
1301 		}
1302 
1303 		if (do_disconnect) {
1304 			if (err)
1305 				disconnect_on_error(client, err);
1306 			else
1307 				disconnect(client);
1308 		}
1309 
1310 		imsg_free(&imsg);
1311 	}
1312 done:
1313 	if (!shut) {
1314 		gotd_imsg_event_add(iev);
1315 	} else {
1316 		/* This pipe is dead. Remove its event handler */
1317 		event_del(&iev->ev);
1318 		disconnect(client);
1319 	}
1320 }
1321 
1322 static void
1323 gotd_dispatch_repo_child(int fd, short event, void *arg)
1324 {
1325 	struct gotd_imsgev *iev = arg;
1326 	struct imsgbuf *ibuf = &iev->ibuf;
1327 	struct gotd_child_proc *proc = NULL;
1328 	struct gotd_client *client;
1329 	ssize_t n;
1330 	int shut = 0;
1331 	struct imsg imsg;
1332 
1333 	client = find_client_by_proc_fd(fd);
1334 	if (client == NULL) {
1335 		/* Can happen during process teardown. */
1336 		warnx("cannot find client for fd %d", fd);
1337 		shut = 1;
1338 		goto done;
1339 	}
1340 
1341 	if (event & EV_READ) {
1342 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1343 			fatal("imsg_read error");
1344 		if (n == 0) {
1345 			/* Connection closed. */
1346 			shut = 1;
1347 			goto done;
1348 		}
1349 	}
1350 
1351 	if (event & EV_WRITE) {
1352 		n = msgbuf_write(&ibuf->w);
1353 		if (n == -1 && errno != EAGAIN)
1354 			fatal("msgbuf_write");
1355 		if (n == 0) {
1356 			/* Connection closed. */
1357 			shut = 1;
1358 			goto done;
1359 		}
1360 	}
1361 
1362 	proc = client->repo;
1363 	if (proc == NULL)
1364 		fatalx("cannot find child process for fd %d", fd);
1365 
1366 	for (;;) {
1367 		const struct got_error *err = NULL;
1368 		uint32_t client_id = 0;
1369 		int do_disconnect = 0;
1370 
1371 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1372 			fatal("%s: imsg_get error", __func__);
1373 		if (n == 0)	/* No more messages. */
1374 			break;
1375 
1376 		switch (imsg.hdr.type) {
1377 		case GOTD_IMSG_ERROR:
1378 			do_disconnect = 1;
1379 			err = gotd_imsg_recv_error(&client_id, &imsg);
1380 			break;
1381 		case GOTD_IMSG_REPO_CHILD_READY:
1382 			err = connect_session(client);
1383 			if (err)
1384 				break;
1385 			err = connect_repo_child(client, proc);
1386 			break;
1387 		default:
1388 			log_debug("unexpected imsg %d", imsg.hdr.type);
1389 			break;
1390 		}
1391 
1392 		if (!verify_imsg_src(client, proc, &imsg)) {
1393 			log_debug("dropping imsg type %d from PID %d",
1394 			    imsg.hdr.type, proc->pid);
1395 			imsg_free(&imsg);
1396 			continue;
1397 		}
1398 		if (err)
1399 			log_warnx("uid %d: %s", client->euid, err->msg);
1400 
1401 		if (do_disconnect) {
1402 			if (err)
1403 				disconnect_on_error(client, err);
1404 			else
1405 				disconnect(client);
1406 		}
1407 
1408 		imsg_free(&imsg);
1409 	}
1410 done:
1411 	if (!shut) {
1412 		gotd_imsg_event_add(iev);
1413 	} else {
1414 		/* This pipe is dead. Remove its event handler */
1415 		event_del(&iev->ev);
1416 		disconnect(client);
1417 	}
1418 }
1419 
1420 static pid_t
1421 start_child(enum gotd_procid proc_id, const char *repo_path,
1422     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1423 {
1424 	char	*argv[11];
1425 	int	 argc = 0;
1426 	pid_t	 pid;
1427 
1428 	switch (pid = fork()) {
1429 	case -1:
1430 		fatal("cannot fork");
1431 	case 0:
1432 		break;
1433 	default:
1434 		close(fd);
1435 		return pid;
1436 	}
1437 
1438 	if (fd != GOTD_FILENO_MSG_PIPE) {
1439 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1440 			fatal("cannot setup imsg fd");
1441 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1442 		fatal("cannot setup imsg fd");
1443 
1444 	argv[argc++] = argv0;
1445 	switch (proc_id) {
1446 	case PROC_LISTEN:
1447 		argv[argc++] = (char *)"-L";
1448 		break;
1449 	case PROC_AUTH:
1450 		argv[argc++] = (char *)"-A";
1451 		break;
1452 	case PROC_SESSION_READ:
1453 		argv[argc++] = (char *)"-s";
1454 		break;
1455 	case PROC_SESSION_WRITE:
1456 		argv[argc++] = (char *)"-S";
1457 		break;
1458 	case PROC_REPO_READ:
1459 		argv[argc++] = (char *)"-R";
1460 		break;
1461 	case PROC_REPO_WRITE:
1462 		argv[argc++] = (char *)"-W";
1463 		break;
1464 	default:
1465 		fatalx("invalid process id %d", proc_id);
1466 	}
1467 
1468 	argv[argc++] = (char *)"-f";
1469 	argv[argc++] = (char *)confpath;
1470 
1471 	if (repo_path) {
1472 		argv[argc++] = (char *)"-P";
1473 		argv[argc++] = (char *)repo_path;
1474 	}
1475 
1476 	if (!daemonize)
1477 		argv[argc++] = (char *)"-d";
1478 	if (verbosity > 0)
1479 		argv[argc++] = (char *)"-v";
1480 	if (verbosity > 1)
1481 		argv[argc++] = (char *)"-v";
1482 	argv[argc++] = NULL;
1483 
1484 	execvp(argv0, argv);
1485 	fatal("execvp");
1486 }
1487 
1488 static void
1489 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1490 {
1491 	struct gotd_child_proc *proc = &gotd.listen_proc;
1492 
1493 	proc->type = PROC_LISTEN;
1494 
1495 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1496 	    PF_UNSPEC, proc->pipe) == -1)
1497 		fatal("socketpair");
1498 
1499 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1500 	    proc->pipe[1], daemonize, verbosity);
1501 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1502 	proc->iev.handler = gotd_dispatch_listener;
1503 	proc->iev.events = EV_READ;
1504 	proc->iev.handler_arg = NULL;
1505 }
1506 
1507 static const struct got_error *
1508 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1509     char *argv0, const char *confpath, int daemonize, int verbosity)
1510 {
1511 	struct gotd_child_proc *proc;
1512 
1513 	proc = calloc(1, sizeof(*proc));
1514 	if (proc == NULL)
1515 		return got_error_from_errno("calloc");
1516 
1517 	if (client_is_reading(client))
1518 		proc->type = PROC_SESSION_READ;
1519 	else
1520 		proc->type = PROC_SESSION_WRITE;
1521 	if (strlcpy(proc->repo_name, repo->name,
1522 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1523 		fatalx("repository name too long: %s", repo->name);
1524 	log_debug("starting client uid %d session for repository %s",
1525 	    client->euid, repo->name);
1526 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1527 	    sizeof(proc->repo_path))
1528 		fatalx("repository path too long: %s", repo->path);
1529 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1530 	    PF_UNSPEC, proc->pipe) == -1)
1531 		fatal("socketpair");
1532 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1533 	    confpath, proc->pipe[1], daemonize, verbosity);
1534 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1535 	log_debug("proc %s %s is on fd %d",
1536 	    gotd_proc_names[proc->type], proc->repo_path,
1537 	    proc->pipe[0]);
1538 	proc->iev.handler = gotd_dispatch_client_session;
1539 	proc->iev.events = EV_READ;
1540 	proc->iev.handler_arg = NULL;
1541 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1542 	    gotd_dispatch_client_session, &proc->iev);
1543 	gotd_imsg_event_add(&proc->iev);
1544 
1545 	client->session = proc;
1546 	return NULL;
1547 }
1548 
1549 static const struct got_error *
1550 start_repo_child(struct gotd_client *client, enum gotd_procid proc_type,
1551     struct gotd_repo *repo, char *argv0, const char *confpath,
1552     int daemonize, int verbosity)
1553 {
1554 	struct gotd_child_proc *proc;
1555 
1556 	if (proc_type != PROC_REPO_READ && proc_type != PROC_REPO_WRITE)
1557 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad process type");
1558 
1559 	proc = calloc(1, sizeof(*proc));
1560 	if (proc == NULL)
1561 		return got_error_from_errno("calloc");
1562 
1563 	proc->type = proc_type;
1564 	if (strlcpy(proc->repo_name, repo->name,
1565 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1566 		fatalx("repository name too long: %s", repo->name);
1567 	log_debug("starting %s for repository %s",
1568 	    proc->type == PROC_REPO_READ ? "reader" : "writer", repo->name);
1569 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1570 	    sizeof(proc->repo_path))
1571 		fatalx("repository path too long: %s", repo->path);
1572 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1573 	    PF_UNSPEC, proc->pipe) == -1)
1574 		fatal("socketpair");
1575 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1576 	    confpath, proc->pipe[1], daemonize, verbosity);
1577 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1578 	log_debug("proc %s %s is on fd %d",
1579 	    gotd_proc_names[proc->type], proc->repo_path,
1580 	    proc->pipe[0]);
1581 	proc->iev.handler = gotd_dispatch_repo_child;
1582 	proc->iev.events = EV_READ;
1583 	proc->iev.handler_arg = NULL;
1584 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1585 	    gotd_dispatch_repo_child, &proc->iev);
1586 	gotd_imsg_event_add(&proc->iev);
1587 
1588 	client->repo = proc;
1589 	return NULL;
1590 }
1591 
1592 static const struct got_error *
1593 start_auth_child(struct gotd_client *client, int required_auth,
1594     struct gotd_repo *repo, char *argv0, const char *confpath,
1595     int daemonize, int verbosity)
1596 {
1597 	const struct got_error *err = NULL;
1598 	struct gotd_child_proc *proc;
1599 	struct gotd_imsg_auth iauth;
1600 	int fd;
1601 
1602 	memset(&iauth, 0, sizeof(iauth));
1603 
1604 	fd = dup(client->fd);
1605 	if (fd == -1)
1606 		return got_error_from_errno("dup");
1607 
1608 	proc = calloc(1, sizeof(*proc));
1609 	if (proc == NULL) {
1610 		err = got_error_from_errno("calloc");
1611 		close(fd);
1612 		return err;
1613 	}
1614 
1615 	proc->type = PROC_AUTH;
1616 	if (strlcpy(proc->repo_name, repo->name,
1617 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1618 		fatalx("repository name too long: %s", repo->name);
1619 	log_debug("starting auth for uid %d repository %s",
1620 	    client->euid, repo->name);
1621 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1622 	    sizeof(proc->repo_path))
1623 		fatalx("repository path too long: %s", repo->path);
1624 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1625 	    PF_UNSPEC, proc->pipe) == -1)
1626 		fatal("socketpair");
1627 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1628 	    confpath, proc->pipe[1], daemonize, verbosity);
1629 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1630 	log_debug("proc %s %s is on fd %d",
1631 	    gotd_proc_names[proc->type], proc->repo_path,
1632 	    proc->pipe[0]);
1633 	proc->iev.handler = gotd_dispatch_auth_child;
1634 	proc->iev.events = EV_READ;
1635 	proc->iev.handler_arg = NULL;
1636 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1637 	    gotd_dispatch_auth_child, &proc->iev);
1638 	gotd_imsg_event_add(&proc->iev);
1639 
1640 	iauth.euid = client->euid;
1641 	iauth.egid = client->egid;
1642 	iauth.required_auth = required_auth;
1643 	iauth.client_id = client->id;
1644 	if (gotd_imsg_compose_event(&proc->iev, GOTD_IMSG_AUTHENTICATE,
1645 	    PROC_GOTD, fd, &iauth, sizeof(iauth)) == -1) {
1646 		log_warn("imsg compose AUTHENTICATE");
1647 		close(fd);
1648 		/* Let the auth_timeout handler tidy up. */
1649 	}
1650 
1651 	client->auth = proc;
1652 	client->required_auth = required_auth;
1653 	return NULL;
1654 }
1655 
1656 static void
1657 apply_unveil_repo_readonly(const char *repo_path, int need_tmpdir)
1658 {
1659 	if (need_tmpdir) {
1660 		if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1661 			fatal("unveil %s", GOT_TMPDIR_STR);
1662 	}
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 	struct gotd_repo *repo = NULL;
1718 
1719 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1720 
1721 	while ((ch = getopt(argc, argv, "Adf:LnP:RsSvW")) != -1) {
1722 		switch (ch) {
1723 		case 'A':
1724 			proc_id = PROC_AUTH;
1725 			break;
1726 		case 'd':
1727 			daemonize = 0;
1728 			break;
1729 		case 'f':
1730 			confpath = optarg;
1731 			break;
1732 		case 'L':
1733 			proc_id = PROC_LISTEN;
1734 			break;
1735 		case 'n':
1736 			noaction = 1;
1737 			break;
1738 		case 'P':
1739 			repo_path = realpath(optarg, NULL);
1740 			if (repo_path == NULL)
1741 				fatal("realpath '%s'", optarg);
1742 			break;
1743 		case 'R':
1744 			proc_id = PROC_REPO_READ;
1745 			break;
1746 		case 's':
1747 			proc_id = PROC_SESSION_READ;
1748 			break;
1749 		case 'S':
1750 			proc_id = PROC_SESSION_WRITE;
1751 			break;
1752 		case 'v':
1753 			if (verbosity < 3)
1754 				verbosity++;
1755 			break;
1756 		case 'W':
1757 			proc_id = PROC_REPO_WRITE;
1758 			break;
1759 		default:
1760 			usage();
1761 		}
1762 	}
1763 
1764 	argc -= optind;
1765 	argv += optind;
1766 
1767 	if (argc != 0)
1768 		usage();
1769 
1770 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1771 		fatalx("need root privileges");
1772 
1773 	if (parse_config(confpath, proc_id, &gotd, 1) != 0)
1774 		return 1;
1775 
1776 	pw = getpwnam(gotd.user_name);
1777 	if (pw == NULL)
1778 		fatalx("user %s not found", gotd.user_name);
1779 
1780 	if (pw->pw_uid == 0)
1781 		fatalx("cannot run %s as the superuser", getprogname());
1782 
1783 	if (noaction) {
1784 		fprintf(stderr, "configuration OK\n");
1785 		return 0;
1786 	}
1787 
1788 	gotd.argv0 = argv0;
1789 	gotd.daemonize = daemonize;
1790 	gotd.verbosity = verbosity;
1791 	gotd.confpath = confpath;
1792 
1793 	/* Require an absolute path in argv[0] for reliable re-exec. */
1794 	if (!got_path_is_absolute(argv0))
1795 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1796 
1797 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1798 	log_setverbose(verbosity);
1799 
1800 	if (proc_id == PROC_GOTD) {
1801 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1802 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1803 		if (daemonize && daemon(1, 0) == -1)
1804 			fatal("daemon");
1805 		gotd.pid = getpid();
1806 		start_listener(argv0, confpath, daemonize, verbosity);
1807 	} else if (proc_id == PROC_LISTEN) {
1808 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1809 		if (verbosity) {
1810 			log_info("socket: %s", gotd.unix_socket_path);
1811 			log_info("user: %s", pw->pw_name);
1812 		}
1813 
1814 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1815 		    pw->pw_gid);
1816 		if (fd == -1) {
1817 			fatal("cannot listen on unix socket %s",
1818 			    gotd.unix_socket_path);
1819 		}
1820 	} else if (proc_id == PROC_AUTH) {
1821 		snprintf(title, sizeof(title), "%s %s",
1822 		    gotd_proc_names[proc_id], repo_path);
1823 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1824 	    proc_id == PROC_SESSION_READ || proc_id == PROC_SESSION_WRITE) {
1825 		error = got_repo_pack_fds_open(&pack_fds);
1826 		if (error != NULL)
1827 			fatalx("cannot open pack tempfiles: %s", error->msg);
1828 		error = got_repo_temp_fds_open(&temp_fds);
1829 		if (error != NULL)
1830 			fatalx("cannot open pack tempfiles: %s", error->msg);
1831 		if (repo_path == NULL)
1832 			fatalx("repository path not specified");
1833 		snprintf(title, sizeof(title), "%s %s",
1834 		    gotd_proc_names[proc_id], repo_path);
1835 	} else
1836 		fatal("invalid process id %d", proc_id);
1837 
1838 	setproctitle("%s", title);
1839 	log_procinit(title);
1840 
1841 	/* Drop root privileges. */
1842 	if (setgid(pw->pw_gid) == -1)
1843 		fatal("setgid %d failed", pw->pw_gid);
1844 	if (setuid(pw->pw_uid) == -1)
1845 		fatal("setuid %d failed", pw->pw_uid);
1846 
1847 	event_init();
1848 
1849 	switch (proc_id) {
1850 	case PROC_GOTD:
1851 #ifndef PROFILE
1852 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1853 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1854 			err(1, "pledge");
1855 #endif
1856 		break;
1857 	case PROC_LISTEN:
1858 #ifndef PROFILE
1859 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1860 			err(1, "pledge");
1861 #endif
1862 		/*
1863 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1864 		 * sockets by revoking all filesystem access via unveil(2).
1865 		 */
1866 		apply_unveil_none();
1867 
1868 		listen_main(title, fd, gotd.connection_limits,
1869 		    gotd.nconnection_limits);
1870 		/* NOTREACHED */
1871 		break;
1872 	case PROC_AUTH:
1873 #ifndef PROFILE
1874 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1875 			err(1, "pledge");
1876 #endif
1877 		/*
1878 		 * We need the "unix" pledge promise for getpeername(2) only.
1879 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1880 		 * filesystem access via unveil(2). Access to password database
1881 		 * files will still work since "getpw" bypasses unveil(2).
1882 		 */
1883 		apply_unveil_none();
1884 
1885 		auth_main(title, &gotd.repos, repo_path);
1886 		/* NOTREACHED */
1887 		break;
1888 	case PROC_SESSION_READ:
1889 	case PROC_SESSION_WRITE:
1890 #ifndef PROFILE
1891 		/*
1892 		 * The "recvfd" promise is only needed during setup and
1893 		 * will be removed in a later pledge(2) call.
1894 		 */
1895 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1896 		    "unveil", NULL) == -1)
1897 			err(1, "pledge");
1898 #endif
1899 		if (proc_id == PROC_SESSION_READ)
1900 			apply_unveil_repo_readonly(repo_path, 1);
1901 		else
1902 			apply_unveil_repo_readwrite(repo_path);
1903 		session_main(title, repo_path, pack_fds, temp_fds,
1904 		    &gotd.request_timeout, proc_id);
1905 		/* NOTREACHED */
1906 		break;
1907 	case PROC_REPO_READ:
1908 #ifndef PROFILE
1909 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1910 			err(1, "pledge");
1911 #endif
1912 		apply_unveil_repo_readonly(repo_path, 0);
1913 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1914 		/* NOTREACHED */
1915 		exit(0);
1916 	case PROC_REPO_WRITE:
1917 #ifndef PROFILE
1918 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1919 			err(1, "pledge");
1920 #endif
1921 		apply_unveil_repo_readonly(repo_path, 0);
1922 		repo = gotd_find_repo_by_path(repo_path, &gotd);
1923 		if (repo == NULL)
1924 			fatalx("no repository for path %s", repo_path);
1925 		repo_write_main(title, repo_path, pack_fds, temp_fds,
1926 		    &repo->protected_tag_namespaces,
1927 		    &repo->protected_branch_namespaces,
1928 		    &repo->protected_branches);
1929 		/* NOTREACHED */
1930 		exit(0);
1931 	default:
1932 		fatal("invalid process id %d", proc_id);
1933 	}
1934 
1935 	if (proc_id != PROC_GOTD)
1936 		fatal("invalid process id %d", proc_id);
1937 
1938 	apply_unveil_selfexec();
1939 
1940 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1941 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1942 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1943 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1944 	signal(SIGPIPE, SIG_IGN);
1945 
1946 	signal_add(&evsigint, NULL);
1947 	signal_add(&evsigterm, NULL);
1948 	signal_add(&evsighup, NULL);
1949 	signal_add(&evsigusr1, NULL);
1950 
1951 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1952 
1953 	event_dispatch();
1954 
1955 	free(repo_path);
1956 	gotd_shutdown();
1957 
1958 	return 0;
1959 }