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 <signal.h>
34 #include <siphash.h>
35 #include <stdarg.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <syslog.h>
40 #include <unistd.h>
41 
42 #include "got_error.h"
43 #include "got_opentemp.h"
44 #include "got_path.h"
45 #include "got_repository.h"
46 #include "got_object.h"
47 #include "got_reference.h"
48 
49 #include "got_lib_delta.h"
50 #include "got_lib_object.h"
51 #include "got_lib_object_cache.h"
52 #include "got_lib_hash.h"
53 #include "got_lib_gitproto.h"
54 #include "got_lib_pack.h"
55 #include "got_lib_repository.h"
56 
57 #include "gotd.h"
58 #include "log.h"
59 #include "listen.h"
60 #include "auth.h"
61 #include "session.h"
62 #include "repo_read.h"
63 #include "repo_write.h"
64 
65 #ifndef nitems
66 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
67 #endif
68 
69 enum gotd_client_state {
70 	GOTD_CLIENT_STATE_NEW,
71 	GOTD_CLIENT_STATE_ACCESS_GRANTED,
72 };
73 
74 struct gotd_client {
75 	STAILQ_ENTRY(gotd_client)	 entry;
76 	enum gotd_client_state		 state;
77 	uint32_t			 id;
78 	int				 fd;
79 	struct gotd_imsgev		 iev;
80 	struct event			 tmo;
81 	uid_t				 euid;
82 	gid_t				 egid;
83 	struct gotd_child_proc		*repo;
84 	struct gotd_child_proc		*auth;
85 	struct gotd_child_proc		*session;
86 	int				 required_auth;
87 };
88 STAILQ_HEAD(gotd_clients, gotd_client);
89 
90 static struct gotd_clients gotd_clients[GOTD_CLIENT_TABLE_SIZE];
91 static SIPHASH_KEY clients_hash_key;
92 volatile int client_cnt;
93 static struct timeval auth_timeout = { 5, 0 };
94 static struct gotd gotd;
95 
96 void gotd_sighdlr(int sig, short event, void *arg);
97 static void gotd_shutdown(void);
98 static const struct got_error *start_session_child(struct gotd_client *,
99     struct gotd_repo *, char *, const char *, int, int);
100 static const struct got_error *start_repo_child(struct gotd_client *,
101     enum gotd_procid, struct gotd_repo *, char *, const char *, int, int);
102 static const struct got_error *start_auth_child(struct gotd_client *, int,
103     struct gotd_repo *, char *, const char *, int, int);
104 static void kill_proc(struct gotd_child_proc *, int);
105 
106 __dead static void
107 usage(void)
108 {
109 	fprintf(stderr, "usage: %s [-dnv] [-f config-file]\n", getprogname());
110 	exit(1);
111 }
112 
113 static int
114 unix_socket_listen(const char *unix_socket_path, uid_t uid, gid_t gid)
115 {
116 	struct sockaddr_un sun;
117 	int fd = -1;
118 	mode_t old_umask, mode;
119 
120 	fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
121 	if (fd == -1) {
122 		log_warn("socket");
123 		return -1;
124 	}
125 
126 	sun.sun_family = AF_UNIX;
127 	if (strlcpy(sun.sun_path, unix_socket_path,
128 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
129 		log_warnx("%s: name too long", unix_socket_path);
130 		close(fd);
131 		return -1;
132 	}
133 
134 	if (unlink(unix_socket_path) == -1) {
135 		if (errno != ENOENT) {
136 			log_warn("unlink %s", unix_socket_path);
137 			close(fd);
138 			return -1;
139 		}
140 	}
141 
142 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
143 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
144 
145 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
146 		log_warn("bind: %s", unix_socket_path);
147 		close(fd);
148 		umask(old_umask);
149 		return -1;
150 	}
151 
152 	umask(old_umask);
153 
154 	if (chmod(unix_socket_path, mode) == -1) {
155 		log_warn("chmod %o %s", mode, unix_socket_path);
156 		close(fd);
157 		unlink(unix_socket_path);
158 		return -1;
159 	}
160 
161 	if (chown(unix_socket_path, uid, gid) == -1) {
162 		log_warn("chown %s uid=%d gid=%d", unix_socket_path, uid, gid);
163 		close(fd);
164 		unlink(unix_socket_path);
165 		return -1;
166 	}
167 
168 	if (listen(fd, GOTD_UNIX_SOCKET_BACKLOG) == -1) {
169 		log_warn("listen");
170 		close(fd);
171 		unlink(unix_socket_path);
172 		return -1;
173 	}
174 
175 	return fd;
176 }
177 
178 static uint64_t
179 client_hash(uint32_t client_id)
180 {
181 	return SipHash24(&clients_hash_key, &client_id, sizeof(client_id));
182 }
183 
184 static void
185 add_client(struct gotd_client *client)
186 {
187 	uint64_t slot = client_hash(client->id) % nitems(gotd_clients);
188 	STAILQ_INSERT_HEAD(&gotd_clients[slot], client, entry);
189 	client_cnt++;
190 }
191 
192 static struct gotd_client *
193 find_client(uint32_t client_id)
194 {
195 	uint64_t slot;
196 	struct gotd_client *c;
197 
198 	slot = client_hash(client_id) % nitems(gotd_clients);
199 	STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
200 		if (c->id == client_id)
201 			return c;
202 	}
203 
204 	return NULL;
205 }
206 
207 static struct gotd_client *
208 find_client_by_proc_fd(int fd)
209 {
210 	uint64_t slot;
211 
212 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
213 		struct gotd_client *c;
214 
215 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
216 			if (c->repo && c->repo->iev.ibuf.fd == fd)
217 				return c;
218 			if (c->auth && c->auth->iev.ibuf.fd == fd)
219 				return c;
220 			if (c->session && c->session->iev.ibuf.fd == fd)
221 				return c;
222 		}
223 	}
224 
225 	return NULL;
226 }
227 
228 static int
229 client_is_reading(struct gotd_client *client)
230 {
231 	return (client->required_auth &
232 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) == GOTD_AUTH_READ;
233 }
234 
235 static int
236 client_is_writing(struct gotd_client *client)
237 {
238 	return (client->required_auth &
239 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) ==
240 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE);
241 }
242 
243 static const struct got_error *
244 ensure_client_is_not_writing(struct gotd_client *client)
245 {
246 	if (client_is_writing(client)) {
247 		return got_error_fmt(GOT_ERR_BAD_PACKET,
248 		    "uid %d made a read-request but is writing to "
249 		    "a repository", client->euid);
250 	}
251 
252 	return NULL;
253 }
254 
255 static const struct got_error *
256 ensure_client_is_not_reading(struct gotd_client *client)
257 {
258 	if (client_is_reading(client)) {
259 		return got_error_fmt(GOT_ERR_BAD_PACKET,
260 		    "uid %d made a write-request but is reading from "
261 		    "a repository", client->euid);
262 	}
263 
264 	return NULL;
265 }
266 
267 static void
268 wait_for_child(pid_t child_pid)
269 {
270 	pid_t pid;
271 	int status;
272 
273 	log_debug("waiting for child PID %ld to terminate",
274 	    (long)child_pid);
275 
276 	do {
277 		pid = waitpid(child_pid, &status, WNOHANG);
278 		if (pid == -1) {
279 			if (errno != EINTR && errno != ECHILD)
280 				fatal("wait");
281 		} else if (WIFSIGNALED(status)) {
282 			log_warnx("child PID %ld terminated; signal %d",
283 			    (long)pid, WTERMSIG(status));
284 		}
285 	} while (pid != -1 || (pid == -1 && errno == EINTR));
286 }
287 
288 static void
289 proc_done(struct gotd_child_proc *proc)
290 {
291 	event_del(&proc->iev.ev);
292 	msgbuf_clear(&proc->iev.ibuf.w);
293 	close(proc->iev.ibuf.fd);
294 	kill_proc(proc, 0);
295 	wait_for_child(proc->pid);
296 	free(proc);
297 }
298 
299 static void
300 kill_auth_proc(struct gotd_client *client)
301 {
302 	struct gotd_child_proc *proc;
303 
304 	if (client->auth == NULL)
305 		return;
306 
307 	proc = client->auth;
308 	client->auth = NULL;
309 
310 	proc_done(proc);
311 }
312 
313 static void
314 kill_session_proc(struct gotd_client *client)
315 {
316 	struct gotd_child_proc *proc;
317 
318 	if (client->session == NULL)
319 		return;
320 
321 	proc = client->session;
322 	client->session = NULL;
323 
324 	proc_done(proc);
325 }
326 
327 static void
328 disconnect(struct gotd_client *client)
329 {
330 	struct gotd_imsg_disconnect idisconnect;
331 	struct gotd_child_proc *proc = client->repo;
332 	struct gotd_child_proc *listen_proc = &gotd.listen_proc;
333 	uint64_t slot;
334 
335 	log_debug("uid %d: disconnecting", client->euid);
336 
337 	kill_auth_proc(client);
338 	kill_session_proc(client);
339 
340 	if (proc) {
341 		event_del(&proc->iev.ev);
342 		msgbuf_clear(&proc->iev.ibuf.w);
343 		close(proc->iev.ibuf.fd);
344 		kill_proc(proc, 0);
345 		wait_for_child(proc->pid);
346 		free(proc);
347 		proc = NULL;
348 	}
349 
350 	idisconnect.client_id = client->id;
351 	if (gotd_imsg_compose_event(&listen_proc->iev,
352 	    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
353 	    &idisconnect, sizeof(idisconnect)) == -1)
354 		log_warn("imsg compose DISCONNECT");
355 
356 	slot = client_hash(client->id) % nitems(gotd_clients);
357 	STAILQ_REMOVE(&gotd_clients[slot], client, gotd_client, entry);
358 	imsg_clear(&client->iev.ibuf);
359 	event_del(&client->iev.ev);
360 	evtimer_del(&client->tmo);
361 	if (client->fd != -1)
362 		close(client->fd);
363 	else if (client->iev.ibuf.fd != -1)
364 		close(client->iev.ibuf.fd);
365 	free(client);
366 	client_cnt--;
367 }
368 
369 static void
370 disconnect_on_error(struct gotd_client *client, const struct got_error *err)
371 {
372 	struct imsgbuf ibuf;
373 
374 	log_warnx("uid %d: %s", client->euid, err->msg);
375 	if (err->code != GOT_ERR_EOF && client->fd != -1) {
376 		imsg_init(&ibuf, client->fd);
377 		gotd_imsg_send_error(&ibuf, 0, PROC_GOTD, err);
378 		imsg_clear(&ibuf);
379 	}
380 	disconnect(client);
381 }
382 
383 static const struct got_error *
384 send_repo_info(struct gotd_imsgev *iev, struct gotd_repo *repo)
385 {
386 	const struct got_error *err = NULL;
387 	struct gotd_imsg_info_repo irepo;
388 
389 	memset(&irepo, 0, sizeof(irepo));
390 
391 	if (strlcpy(irepo.repo_name, repo->name, sizeof(irepo.repo_name))
392 	    >= sizeof(irepo.repo_name))
393 		return got_error_msg(GOT_ERR_NO_SPACE, "repo name too long");
394 	if (strlcpy(irepo.repo_path, repo->path, sizeof(irepo.repo_path))
395 	    >= sizeof(irepo.repo_path))
396 		return got_error_msg(GOT_ERR_NO_SPACE, "repo path too long");
397 
398 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_REPO, PROC_GOTD, -1,
399 	    &irepo, sizeof(irepo)) == -1) {
400 		err = got_error_from_errno("imsg compose INFO_REPO");
401 		if (err)
402 			return err;
403 	}
404 
405 	return NULL;
406 }
407 
408 static const struct got_error *
409 send_client_info(struct gotd_imsgev *iev, struct gotd_client *client)
410 {
411 	const struct got_error *err = NULL;
412 	struct gotd_imsg_info_client iclient;
413 	struct gotd_child_proc *proc;
414 
415 	memset(&iclient, 0, sizeof(iclient));
416 	iclient.euid = client->euid;
417 	iclient.egid = client->egid;
418 
419 	proc = client->repo;
420 	if (proc) {
421 		if (strlcpy(iclient.repo_name, proc->repo_path,
422 		    sizeof(iclient.repo_name)) >= sizeof(iclient.repo_name)) {
423 			return got_error_msg(GOT_ERR_NO_SPACE,
424 			    "repo name too long");
425 		}
426 		if (client_is_writing(client))
427 			iclient.is_writing = 1;
428 
429 		iclient.repo_child_pid = proc->pid;
430 	}
431 
432 	if (client->session)
433 		iclient.session_child_pid = client->session->pid;
434 
435 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_CLIENT, PROC_GOTD, -1,
436 	    &iclient, sizeof(iclient)) == -1) {
437 		err = got_error_from_errno("imsg compose INFO_CLIENT");
438 		if (err)
439 			return err;
440 	}
441 
442 	return NULL;
443 }
444 
445 static const struct got_error *
446 send_info(struct gotd_client *client)
447 {
448 	const struct got_error *err = NULL;
449 	struct gotd_imsg_info info;
450 	uint64_t slot;
451 	struct gotd_repo *repo;
452 
453 	if (client->euid != 0)
454 		return got_error_set_errno(EPERM, "info");
455 
456 	info.pid = gotd.pid;
457 	info.verbosity = gotd.verbosity;
458 	info.nrepos = gotd.nrepos;
459 	info.nclients = client_cnt - 1;
460 
461 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_INFO, PROC_GOTD, -1,
462 	    &info, sizeof(info)) == -1) {
463 		err = got_error_from_errno("imsg compose INFO");
464 		if (err)
465 			return err;
466 	}
467 
468 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
469 		err = send_repo_info(&client->iev, repo);
470 		if (err)
471 			return err;
472 	}
473 
474 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
475 		struct gotd_client *c;
476 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
477 			if (c->id == client->id)
478 				continue;
479 			err = send_client_info(&client->iev, c);
480 			if (err)
481 				return err;
482 		}
483 	}
484 
485 	return NULL;
486 }
487 
488 static const struct got_error *
489 stop_gotd(struct gotd_client *client)
490 {
491 
492 	if (client->euid != 0)
493 		return got_error_set_errno(EPERM, "stop");
494 
495 	gotd_shutdown();
496 	/* NOTREACHED */
497 	return NULL;
498 }
499 
500 static struct gotd_repo *
501 find_repo_by_name(const char *repo_name)
502 {
503 	struct gotd_repo *repo;
504 	size_t namelen;
505 
506 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
507 		namelen = strlen(repo->name);
508 		if (strncmp(repo->name, repo_name, namelen) != 0)
509 			continue;
510 		if (repo_name[namelen] == '\0' ||
511 		    strcmp(&repo_name[namelen], ".git") == 0)
512 			return repo;
513 	}
514 
515 	return NULL;
516 }
517 
518 static const struct got_error *
519 start_client_authentication(struct gotd_client *client, struct imsg *imsg)
520 {
521 	const struct got_error *err;
522 	struct gotd_imsg_list_refs ireq;
523 	struct gotd_repo *repo = NULL;
524 	size_t datalen;
525 
526 	log_debug("list-refs request from uid %d", client->euid);
527 
528 	if (client->state != GOTD_CLIENT_STATE_NEW)
529 		return got_error_msg(GOT_ERR_BAD_REQUEST,
530 		    "unexpected list-refs request received");
531 
532 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
533 	if (datalen != sizeof(ireq))
534 		return got_error(GOT_ERR_PRIVSEP_LEN);
535 
536 	memcpy(&ireq, imsg->data, datalen);
537 
538 	if (ireq.client_is_reading) {
539 		err = ensure_client_is_not_writing(client);
540 		if (err)
541 			return err;
542 		repo = find_repo_by_name(ireq.repo_name);
543 		if (repo == NULL)
544 			return got_error(GOT_ERR_NOT_GIT_REPO);
545 		err = start_auth_child(client, GOTD_AUTH_READ, repo,
546 		    gotd.argv0, gotd.confpath, gotd.daemonize,
547 		    gotd.verbosity);
548 		if (err)
549 			return err;
550 	} else {
551 		err = ensure_client_is_not_reading(client);
552 		if (err)
553 			return err;
554 		repo = find_repo_by_name(ireq.repo_name);
555 		if (repo == NULL)
556 			return got_error(GOT_ERR_NOT_GIT_REPO);
557 		err = start_auth_child(client,
558 		    GOTD_AUTH_READ | GOTD_AUTH_WRITE,
559 		    repo, gotd.argv0, gotd.confpath, gotd.daemonize,
560 		    gotd.verbosity);
561 		if (err)
562 			return err;
563 	}
564 
565 	evtimer_add(&client->tmo, &auth_timeout);
566 
567 	/* Flow continues upon authentication successs/failure or timeout. */
568 	return NULL;
569 }
570 
571 static void
572 gotd_request(int fd, short events, void *arg)
573 {
574 	struct gotd_imsgev *iev = arg;
575 	struct imsgbuf *ibuf = &iev->ibuf;
576 	struct gotd_client *client = iev->handler_arg;
577 	const struct got_error *err = NULL;
578 	struct imsg imsg;
579 	ssize_t n;
580 
581 	if (events & EV_WRITE) {
582 		while (ibuf->w.queued) {
583 			n = msgbuf_write(&ibuf->w);
584 			if (n == -1 && errno == EPIPE) {
585 				/*
586 				 * The client has closed its socket.
587 				 * This can happen when Git clients are
588 				 * done sending pack file data.
589 				 */
590 				msgbuf_clear(&ibuf->w);
591 				continue;
592 			} else if (n == -1 && errno != EAGAIN) {
593 				err = got_error_from_errno("imsg_flush");
594 				disconnect_on_error(client, err);
595 				return;
596 			}
597 			if (n == 0) {
598 				/* Connection closed. */
599 				err = got_error(GOT_ERR_EOF);
600 				disconnect_on_error(client, err);
601 				return;
602 			}
603 		}
604 
605 		/* Disconnect gotctl(8) now that messages have been sent. */
606 		if (!client_is_reading(client) && !client_is_writing(client)) {
607 			disconnect(client);
608 			return;
609 		}
610 	}
611 
612 	if ((events & EV_READ) == 0)
613 		return;
614 
615 	memset(&imsg, 0, sizeof(imsg));
616 
617 	while (err == NULL) {
618 		err = gotd_imsg_recv(&imsg, ibuf, 0);
619 		if (err) {
620 			if (err->code == GOT_ERR_PRIVSEP_READ)
621 				err = NULL;
622 			break;
623 		}
624 
625 		evtimer_del(&client->tmo);
626 
627 		switch (imsg.hdr.type) {
628 		case GOTD_IMSG_INFO:
629 			err = send_info(client);
630 			break;
631 		case GOTD_IMSG_STOP:
632 			err = stop_gotd(client);
633 			break;
634 		case GOTD_IMSG_LIST_REFS:
635 			err = start_client_authentication(client, &imsg);
636 			break;
637 		default:
638 			log_debug("unexpected imsg %d", imsg.hdr.type);
639 			err = got_error(GOT_ERR_PRIVSEP_MSG);
640 			break;
641 		}
642 
643 		imsg_free(&imsg);
644 	}
645 
646 	if (err) {
647 		disconnect_on_error(client, err);
648 	} else {
649 		gotd_imsg_event_add(&client->iev);
650 	}
651 }
652 
653 static void
654 gotd_auth_timeout(int fd, short events, void *arg)
655 {
656 	struct gotd_client *client = arg;
657 
658 	log_debug("disconnecting uid %d due to authentication timeout",
659 	    client->euid);
660 	disconnect(client);
661 }
662 
663 static const struct got_error *
664 recv_connect(uint32_t *client_id, struct imsg *imsg)
665 {
666 	const struct got_error *err = NULL;
667 	struct gotd_imsg_connect iconnect;
668 	size_t datalen;
669 	int s = -1;
670 	struct gotd_client *client = NULL;
671 
672 	*client_id = 0;
673 
674 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
675 	if (datalen != sizeof(iconnect))
676 		return got_error(GOT_ERR_PRIVSEP_LEN);
677 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
678 
679 	s = imsg->fd;
680 	if (s == -1) {
681 		err = got_error(GOT_ERR_PRIVSEP_NO_FD);
682 		goto done;
683 	}
684 
685 	if (find_client(iconnect.client_id)) {
686 		err = got_error_msg(GOT_ERR_CLIENT_ID, "duplicate client ID");
687 		goto done;
688 	}
689 
690 	client = calloc(1, sizeof(*client));
691 	if (client == NULL) {
692 		err = got_error_from_errno("calloc");
693 		goto done;
694 	}
695 
696 	*client_id = iconnect.client_id;
697 
698 	client->state = GOTD_CLIENT_STATE_NEW;
699 	client->id = iconnect.client_id;
700 	client->fd = s;
701 	s = -1;
702 	/* The auth process will verify UID/GID for us. */
703 	client->euid = iconnect.euid;
704 	client->egid = iconnect.egid;
705 
706 	imsg_init(&client->iev.ibuf, client->fd);
707 	client->iev.handler = gotd_request;
708 	client->iev.events = EV_READ;
709 	client->iev.handler_arg = client;
710 
711 	event_set(&client->iev.ev, client->fd, EV_READ, gotd_request,
712 	    &client->iev);
713 	gotd_imsg_event_add(&client->iev);
714 
715 	evtimer_set(&client->tmo, gotd_auth_timeout, client);
716 
717 	add_client(client);
718 	log_debug("%s: new client uid %d connected on fd %d", __func__,
719 	    client->euid, client->fd);
720 done:
721 	if (err) {
722 		struct gotd_child_proc *listen_proc = &gotd.listen_proc;
723 		struct gotd_imsg_disconnect idisconnect;
724 
725 		idisconnect.client_id = client->id;
726 		if (gotd_imsg_compose_event(&listen_proc->iev,
727 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
728 		    &idisconnect, sizeof(idisconnect)) == -1)
729 			log_warn("imsg compose DISCONNECT");
730 
731 		if (s != -1)
732 			close(s);
733 	}
734 
735 	return err;
736 }
737 
738 static const char *gotd_proc_names[PROC_MAX] = {
739 	"parent",
740 	"listen",
741 	"auth",
742 	"session",
743 	"repo_read",
744 	"repo_write"
745 };
746 
747 static void
748 kill_proc(struct gotd_child_proc *proc, int fatal)
749 {
750 	if (fatal) {
751 		log_warnx("sending SIGKILL to PID %d", proc->pid);
752 		kill(proc->pid, SIGKILL);
753 	} else
754 		kill(proc->pid, SIGTERM);
755 }
756 
757 static void
758 gotd_shutdown(void)
759 {
760 	struct gotd_child_proc *proc;
761 	uint64_t slot;
762 
763 	log_debug("shutting down");
764 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
765 		struct gotd_client *c, *tmp;
766 
767 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
768 			disconnect(c);
769 	}
770 
771 	proc = &gotd.listen_proc;
772 	msgbuf_clear(&proc->iev.ibuf.w);
773 	close(proc->iev.ibuf.fd);
774 	kill_proc(proc, 0);
775 	wait_for_child(proc->pid);
776 
777 	log_info("terminating");
778 	exit(0);
779 }
780 
781 void
782 gotd_sighdlr(int sig, short event, void *arg)
783 {
784 	/*
785 	 * Normal signal handler rules don't apply because libevent
786 	 * decouples for us.
787 	 */
788 
789 	switch (sig) {
790 	case SIGHUP:
791 		log_info("%s: ignoring SIGHUP", __func__);
792 		break;
793 	case SIGUSR1:
794 		log_info("%s: ignoring SIGUSR1", __func__);
795 		break;
796 	case SIGTERM:
797 	case SIGINT:
798 		gotd_shutdown();
799 		break;
800 	default:
801 		fatalx("unexpected signal");
802 	}
803 }
804 
805 static const struct got_error *
806 ensure_proc_is_reading(struct gotd_client *client,
807     struct gotd_child_proc *proc)
808 {
809 	if (!client_is_reading(client)) {
810 		kill_proc(proc, 1);
811 		return got_error_fmt(GOT_ERR_BAD_PACKET,
812 		    "PID %d handled a read-request for uid %d but this "
813 		    "user is not reading from a repository", proc->pid,
814 		    client->euid);
815 	}
816 
817 	return NULL;
818 }
819 
820 static const struct got_error *
821 ensure_proc_is_writing(struct gotd_client *client,
822     struct gotd_child_proc *proc)
823 {
824 	if (!client_is_writing(client)) {
825 		kill_proc(proc, 1);
826 		return got_error_fmt(GOT_ERR_BAD_PACKET,
827 		    "PID %d handled a write-request for uid %d but this "
828 		    "user is not writing to a repository", proc->pid,
829 		    client->euid);
830 	}
831 
832 	return NULL;
833 }
834 
835 static int
836 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
837     struct imsg *imsg)
838 {
839 	const struct got_error *err;
840 	int ret = 0;
841 
842 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
843 		if (client->repo == NULL)
844 			fatalx("no process found for uid %d", client->euid);
845 		if (proc->pid != client->repo->pid) {
846 			kill_proc(proc, 1);
847 			log_warnx("received message from PID %d for uid %d, "
848 			    "while PID %d is the process serving this user",
849 			    proc->pid, client->euid, client->repo->pid);
850 			return 0;
851 		}
852 	}
853 	if (proc->type == PROC_SESSION) {
854 		if (client->session == NULL) {
855 			log_warnx("no session found for uid %d", client->euid);
856 			return 0;
857 		}
858 		if (proc->pid != client->session->pid) {
859 			kill_proc(proc, 1);
860 			log_warnx("received message from PID %d for uid %d, "
861 			    "while PID %d is the process serving this user",
862 			    proc->pid, client->euid, client->session->pid);
863 			return 0;
864 		}
865 	}
866 
867 	switch (imsg->hdr.type) {
868 	case GOTD_IMSG_ERROR:
869 		ret = 1;
870 		break;
871 	case GOTD_IMSG_CONNECT:
872 		if (proc->type != PROC_LISTEN) {
873 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
874 			    "new connection for uid %d from PID %d "
875 			    "which is not the listen process",
876 			    proc->pid, client->euid);
877 		} else
878 			ret = 1;
879 		break;
880 	case GOTD_IMSG_ACCESS_GRANTED:
881 		if (proc->type != PROC_AUTH) {
882 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
883 			    "authentication of uid %d from PID %d "
884 			    "which is not the auth process",
885 			    proc->pid, client->euid);
886 		} else
887 			ret = 1;
888 		break;
889 	case GOTD_IMSG_CLIENT_SESSION_READY:
890 		if (proc->type != PROC_SESSION) {
891 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
892 			    "unexpected \"ready\" signal from PID %d",
893 			    proc->pid);
894 		} else
895 			ret = 1;
896 		break;
897 	case GOTD_IMSG_REPO_CHILD_READY:
898 		if (proc->type != PROC_REPO_READ &&
899 		    proc->type != PROC_REPO_WRITE) {
900 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
901 			    "unexpected \"ready\" signal from PID %d",
902 			    proc->pid);
903 		} else
904 			ret = 1;
905 		break;
906 	case GOTD_IMSG_PACKFILE_DONE:
907 		err = ensure_proc_is_reading(client, proc);
908 		if (err)
909 			log_warnx("uid %d: %s", client->euid, err->msg);
910 		else
911 			ret = 1;
912 		break;
913 	case GOTD_IMSG_PACKFILE_INSTALL:
914 	case GOTD_IMSG_REF_UPDATES_START:
915 	case GOTD_IMSG_REF_UPDATE:
916 		err = ensure_proc_is_writing(client, proc);
917 		if (err)
918 			log_warnx("uid %d: %s", client->euid, err->msg);
919 		else
920 			ret = 1;
921 		break;
922 	default:
923 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
924 		break;
925 	}
926 
927 	return ret;
928 }
929 
930 static const struct got_error *
931 connect_repo_child(struct gotd_client *client,
932     struct gotd_child_proc *repo_proc)
933 {
934 	static const struct got_error *err;
935 	struct gotd_imsgev *session_iev = &client->session->iev;
936 	struct gotd_imsg_connect_repo_child ireq;
937 	int pipe[2];
938 
939 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
940 		return got_error_msg(GOT_ERR_BAD_REQUEST,
941 		    "unexpected repo child ready signal received");
942 
943 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
944 	    PF_UNSPEC, pipe) == -1)
945 		fatal("socketpair");
946 
947 	memset(&ireq, 0, sizeof(ireq));
948 	ireq.client_id = client->id;
949 	ireq.proc_id = repo_proc->type;
950 
951 	/* Pass repo child pipe to session child process. */
952 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
953 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
954 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
955 		close(pipe[0]);
956 		close(pipe[1]);
957 		return err;
958 	}
959 
960 	/* Pass session child pipe to repo child process. */
961 	if (gotd_imsg_compose_event(&repo_proc->iev,
962 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
963 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
964 		close(pipe[1]);
965 		return err;
966 	}
967 
968 	return NULL;
969 }
970 
971 static void
972 gotd_dispatch_listener(int fd, short event, void *arg)
973 {
974 	struct gotd_imsgev *iev = arg;
975 	struct imsgbuf *ibuf = &iev->ibuf;
976 	struct gotd_child_proc *proc = &gotd.listen_proc;
977 	ssize_t n;
978 	int shut = 0;
979 	struct imsg imsg;
980 
981 	if (proc->iev.ibuf.fd != fd)
982 		fatalx("%s: unexpected fd %d", __func__, fd);
983 
984 	if (event & EV_READ) {
985 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
986 			fatal("imsg_read error");
987 		if (n == 0) {
988 			/* Connection closed. */
989 			shut = 1;
990 			goto done;
991 		}
992 	}
993 
994 	if (event & EV_WRITE) {
995 		n = msgbuf_write(&ibuf->w);
996 		if (n == -1 && errno != EAGAIN)
997 			fatal("msgbuf_write");
998 		if (n == 0) {
999 			/* Connection closed. */
1000 			shut = 1;
1001 			goto done;
1002 		}
1003 	}
1004 
1005 	for (;;) {
1006 		const struct got_error *err = NULL;
1007 		struct gotd_client *client = NULL;
1008 		uint32_t client_id = 0;
1009 		int do_disconnect = 0;
1010 
1011 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1012 			fatal("%s: imsg_get error", __func__);
1013 		if (n == 0)	/* No more messages. */
1014 			break;
1015 
1016 		switch (imsg.hdr.type) {
1017 		case GOTD_IMSG_ERROR:
1018 			do_disconnect = 1;
1019 			err = gotd_imsg_recv_error(&client_id, &imsg);
1020 			break;
1021 		case GOTD_IMSG_CONNECT:
1022 			err = recv_connect(&client_id, &imsg);
1023 			break;
1024 		default:
1025 			log_debug("unexpected imsg %d", imsg.hdr.type);
1026 			break;
1027 		}
1028 
1029 		client = find_client(client_id);
1030 		if (client == NULL) {
1031 			log_warnx("%s: client not found", __func__);
1032 			imsg_free(&imsg);
1033 			continue;
1034 		}
1035 
1036 		if (err)
1037 			log_warnx("uid %d: %s", client->euid, err->msg);
1038 
1039 		if (do_disconnect) {
1040 			if (err)
1041 				disconnect_on_error(client, err);
1042 			else
1043 				disconnect(client);
1044 		}
1045 
1046 		imsg_free(&imsg);
1047 	}
1048 done:
1049 	if (!shut) {
1050 		gotd_imsg_event_add(iev);
1051 	} else {
1052 		/* This pipe is dead. Remove its event handler */
1053 		event_del(&iev->ev);
1054 		event_loopexit(NULL);
1055 	}
1056 }
1057 
1058 static void
1059 gotd_dispatch_auth_child(int fd, short event, void *arg)
1060 {
1061 	const struct got_error *err = NULL;
1062 	struct gotd_imsgev *iev = arg;
1063 	struct imsgbuf *ibuf = &iev->ibuf;
1064 	struct gotd_client *client;
1065 	struct gotd_repo *repo = NULL;
1066 	ssize_t n;
1067 	int shut = 0;
1068 	struct imsg imsg;
1069 	uint32_t client_id = 0;
1070 	int do_disconnect = 0;
1071 
1072 	client = find_client_by_proc_fd(fd);
1073 	if (client == NULL) {
1074 		/* Can happen during process teardown. */
1075 		warnx("cannot find client for fd %d", fd);
1076 		shut = 1;
1077 		goto done;
1078 	}
1079 
1080 	if (client->auth == NULL)
1081 		fatalx("cannot find auth child process for fd %d", fd);
1082 
1083 	if (event & EV_READ) {
1084 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1085 			fatal("imsg_read error");
1086 		if (n == 0) {
1087 			/* Connection closed. */
1088 			shut = 1;
1089 			goto done;
1090 		}
1091 	}
1092 
1093 	if (event & EV_WRITE) {
1094 		n = msgbuf_write(&ibuf->w);
1095 		if (n == -1 && errno != EAGAIN)
1096 			fatal("msgbuf_write");
1097 		if (n == 0) {
1098 			/* Connection closed. */
1099 			shut = 1;
1100 		}
1101 		goto done;
1102 	}
1103 
1104 	if (client->auth->iev.ibuf.fd != fd)
1105 		fatalx("%s: unexpected fd %d", __func__, fd);
1106 
1107 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1108 		fatal("%s: imsg_get error", __func__);
1109 	if (n == 0)	/* No more messages. */
1110 		return;
1111 
1112 	evtimer_del(&client->tmo);
1113 
1114 	switch (imsg.hdr.type) {
1115 	case GOTD_IMSG_ERROR:
1116 		do_disconnect = 1;
1117 		err = gotd_imsg_recv_error(&client_id, &imsg);
1118 		break;
1119 	case GOTD_IMSG_ACCESS_GRANTED:
1120 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1121 		break;
1122 	default:
1123 		do_disconnect = 1;
1124 		log_debug("unexpected imsg %d", imsg.hdr.type);
1125 		break;
1126 	}
1127 
1128 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1129 		do_disconnect = 1;
1130 		log_debug("dropping imsg type %d from PID %d",
1131 		    imsg.hdr.type, client->auth->pid);
1132 	}
1133 	imsg_free(&imsg);
1134 
1135 	if (do_disconnect) {
1136 		if (err)
1137 			disconnect_on_error(client, err);
1138 		else
1139 			disconnect(client);
1140 		goto done;
1141 	}
1142 
1143 	repo = find_repo_by_name(client->auth->repo_name);
1144 	if (repo == NULL) {
1145 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1146 		goto done;
1147 	}
1148 	kill_auth_proc(client);
1149 
1150 	log_info("authenticated uid %d for repository %s",
1151 	    client->euid, repo->name);
1152 
1153 	err = start_session_child(client, repo, gotd.argv0,
1154 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1155 	if (err)
1156 		goto done;
1157 done:
1158 	if (err)
1159 		log_warnx("uid %d: %s", client->euid, err->msg);
1160 
1161 	/* We might have killed the auth process by now. */
1162 	if (client->auth != NULL) {
1163 		if (!shut) {
1164 			gotd_imsg_event_add(iev);
1165 		} else {
1166 			/* This pipe is dead. Remove its event handler */
1167 			event_del(&iev->ev);
1168 		}
1169 	}
1170 }
1171 
1172 static const struct got_error *
1173 connect_session(struct gotd_client *client)
1174 {
1175 	const struct got_error *err = NULL;
1176 	struct gotd_imsg_connect iconnect;
1177 	int s;
1178 
1179 	memset(&iconnect, 0, sizeof(iconnect));
1180 
1181 	s = dup(client->fd);
1182 	if (s == -1)
1183 		return got_error_from_errno("dup");
1184 
1185 	iconnect.client_id = client->id;
1186 	iconnect.euid = client->euid;
1187 	iconnect.egid = client->egid;
1188 
1189 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1190 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1191 		err = got_error_from_errno("imsg compose CONNECT");
1192 		close(s);
1193 		return err;
1194 	}
1195 
1196 	/*
1197 	 * We are no longer interested in messages from this client.
1198 	 * Further client requests will be handled by the session process.
1199 	 */
1200 	msgbuf_clear(&client->iev.ibuf.w);
1201 	imsg_clear(&client->iev.ibuf);
1202 	event_del(&client->iev.ev);
1203 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1204 
1205 	return NULL;
1206 }
1207 
1208 static void
1209 gotd_dispatch_client_session(int fd, short event, void *arg)
1210 {
1211 	struct gotd_imsgev *iev = arg;
1212 	struct imsgbuf *ibuf = &iev->ibuf;
1213 	struct gotd_child_proc *proc = NULL;
1214 	struct gotd_client *client = NULL;
1215 	ssize_t n;
1216 	int shut = 0;
1217 	struct imsg imsg;
1218 
1219 	client = find_client_by_proc_fd(fd);
1220 	if (client == NULL) {
1221 		/* Can happen during process teardown. */
1222 		warnx("cannot find client for fd %d", fd);
1223 		shut = 1;
1224 		goto done;
1225 	}
1226 
1227 	if (event & EV_READ) {
1228 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1229 			fatal("imsg_read error");
1230 		if (n == 0) {
1231 			/* Connection closed. */
1232 			shut = 1;
1233 			goto done;
1234 		}
1235 	}
1236 
1237 	if (event & EV_WRITE) {
1238 		n = msgbuf_write(&ibuf->w);
1239 		if (n == -1 && errno != EAGAIN)
1240 			fatal("msgbuf_write");
1241 		if (n == 0) {
1242 			/* Connection closed. */
1243 			shut = 1;
1244 			goto done;
1245 		}
1246 	}
1247 
1248 	proc = client->session;
1249 	if (proc == NULL)
1250 		fatalx("cannot find session child process for fd %d", fd);
1251 
1252 	for (;;) {
1253 		const struct got_error *err = NULL;
1254 		uint32_t client_id = 0;
1255 		int do_disconnect = 0, do_start_repo_child = 0;
1256 
1257 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1258 			fatal("%s: imsg_get error", __func__);
1259 		if (n == 0)	/* No more messages. */
1260 			break;
1261 
1262 		switch (imsg.hdr.type) {
1263 		case GOTD_IMSG_ERROR:
1264 			do_disconnect = 1;
1265 			err = gotd_imsg_recv_error(&client_id, &imsg);
1266 			break;
1267 		case GOTD_IMSG_CLIENT_SESSION_READY:
1268 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1269 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1270 				break;
1271 			}
1272 			do_start_repo_child = 1;
1273 			break;
1274 		case GOTD_IMSG_DISCONNECT:
1275 			do_disconnect = 1;
1276 			break;
1277 		default:
1278 			log_debug("unexpected imsg %d", imsg.hdr.type);
1279 			break;
1280 		}
1281 
1282 		if (!verify_imsg_src(client, proc, &imsg)) {
1283 			log_debug("dropping imsg type %d from PID %d",
1284 			    imsg.hdr.type, proc->pid);
1285 			imsg_free(&imsg);
1286 			continue;
1287 		}
1288 		if (err)
1289 			log_warnx("uid %d: %s", client->euid, err->msg);
1290 
1291 		if (do_start_repo_child) {
1292 			struct gotd_repo *repo;
1293 
1294 			repo = find_repo_by_name(client->session->repo_name);
1295 			if (repo != NULL) {
1296 				enum gotd_procid proc_type;
1297 
1298 				if (client->required_auth & GOTD_AUTH_WRITE)
1299 					proc_type = PROC_REPO_WRITE;
1300 				else
1301 					proc_type = PROC_REPO_READ;
1302 
1303 				err = start_repo_child(client, proc_type, repo,
1304 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1305 				    gotd.verbosity);
1306 			} else
1307 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1308 
1309 			if (err) {
1310 				log_warnx("uid %d: %s", client->euid, err->msg);
1311 				do_disconnect = 1;
1312 			}
1313 		}
1314 
1315 		if (do_disconnect) {
1316 			if (err)
1317 				disconnect_on_error(client, err);
1318 			else
1319 				disconnect(client);
1320 		}
1321 
1322 		imsg_free(&imsg);
1323 	}
1324 done:
1325 	if (!shut) {
1326 		gotd_imsg_event_add(iev);
1327 	} else {
1328 		/* This pipe is dead. Remove its event handler */
1329 		event_del(&iev->ev);
1330 		disconnect(client);
1331 	}
1332 }
1333 
1334 static void
1335 gotd_dispatch_repo_child(int fd, short event, void *arg)
1336 {
1337 	struct gotd_imsgev *iev = arg;
1338 	struct imsgbuf *ibuf = &iev->ibuf;
1339 	struct gotd_child_proc *proc = NULL;
1340 	struct gotd_client *client;
1341 	ssize_t n;
1342 	int shut = 0;
1343 	struct imsg imsg;
1344 
1345 	client = find_client_by_proc_fd(fd);
1346 	if (client == NULL) {
1347 		/* Can happen during process teardown. */
1348 		warnx("cannot find client for fd %d", fd);
1349 		shut = 1;
1350 		goto done;
1351 	}
1352 
1353 	if (event & EV_READ) {
1354 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1355 			fatal("imsg_read error");
1356 		if (n == 0) {
1357 			/* Connection closed. */
1358 			shut = 1;
1359 			goto done;
1360 		}
1361 	}
1362 
1363 	if (event & EV_WRITE) {
1364 		n = msgbuf_write(&ibuf->w);
1365 		if (n == -1 && errno != EAGAIN)
1366 			fatal("msgbuf_write");
1367 		if (n == 0) {
1368 			/* Connection closed. */
1369 			shut = 1;
1370 			goto done;
1371 		}
1372 	}
1373 
1374 	proc = client->repo;
1375 	if (proc == NULL)
1376 		fatalx("cannot find child process for fd %d", fd);
1377 
1378 	for (;;) {
1379 		const struct got_error *err = NULL;
1380 		uint32_t client_id = 0;
1381 		int do_disconnect = 0;
1382 
1383 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1384 			fatal("%s: imsg_get error", __func__);
1385 		if (n == 0)	/* No more messages. */
1386 			break;
1387 
1388 		switch (imsg.hdr.type) {
1389 		case GOTD_IMSG_ERROR:
1390 			do_disconnect = 1;
1391 			err = gotd_imsg_recv_error(&client_id, &imsg);
1392 			break;
1393 		case GOTD_IMSG_REPO_CHILD_READY:
1394 			err = connect_session(client);
1395 			if (err)
1396 				break;
1397 			err = connect_repo_child(client, proc);
1398 			break;
1399 		default:
1400 			log_debug("unexpected imsg %d", imsg.hdr.type);
1401 			break;
1402 		}
1403 
1404 		if (!verify_imsg_src(client, proc, &imsg)) {
1405 			log_debug("dropping imsg type %d from PID %d",
1406 			    imsg.hdr.type, proc->pid);
1407 			imsg_free(&imsg);
1408 			continue;
1409 		}
1410 		if (err)
1411 			log_warnx("uid %d: %s", client->euid, err->msg);
1412 
1413 		if (do_disconnect) {
1414 			if (err)
1415 				disconnect_on_error(client, err);
1416 			else
1417 				disconnect(client);
1418 		}
1419 
1420 		imsg_free(&imsg);
1421 	}
1422 done:
1423 	if (!shut) {
1424 		gotd_imsg_event_add(iev);
1425 	} else {
1426 		/* This pipe is dead. Remove its event handler */
1427 		event_del(&iev->ev);
1428 		disconnect(client);
1429 	}
1430 }
1431 
1432 static pid_t
1433 start_child(enum gotd_procid proc_id, const char *repo_path,
1434     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1435 {
1436 	char	*argv[11];
1437 	int	 argc = 0;
1438 	pid_t	 pid;
1439 
1440 	switch (pid = fork()) {
1441 	case -1:
1442 		fatal("cannot fork");
1443 	case 0:
1444 		break;
1445 	default:
1446 		close(fd);
1447 		return pid;
1448 	}
1449 
1450 	if (fd != GOTD_FILENO_MSG_PIPE) {
1451 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1452 			fatal("cannot setup imsg fd");
1453 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1454 		fatal("cannot setup imsg fd");
1455 
1456 	argv[argc++] = argv0;
1457 	switch (proc_id) {
1458 	case PROC_LISTEN:
1459 		argv[argc++] = (char *)"-L";
1460 		break;
1461 	case PROC_AUTH:
1462 		argv[argc++] = (char *)"-A";
1463 		break;
1464 	case PROC_SESSION:
1465 		argv[argc++] = (char *)"-S";
1466 		break;
1467 	case PROC_REPO_READ:
1468 		argv[argc++] = (char *)"-R";
1469 		break;
1470 	case PROC_REPO_WRITE:
1471 		argv[argc++] = (char *)"-W";
1472 		break;
1473 	default:
1474 		fatalx("invalid process id %d", proc_id);
1475 	}
1476 
1477 	argv[argc++] = (char *)"-f";
1478 	argv[argc++] = (char *)confpath;
1479 
1480 	if (repo_path) {
1481 		argv[argc++] = (char *)"-P";
1482 		argv[argc++] = (char *)repo_path;
1483 	}
1484 
1485 	if (!daemonize)
1486 		argv[argc++] = (char *)"-d";
1487 	if (verbosity > 0)
1488 		argv[argc++] = (char *)"-v";
1489 	if (verbosity > 1)
1490 		argv[argc++] = (char *)"-v";
1491 	argv[argc++] = NULL;
1492 
1493 	execvp(argv0, argv);
1494 	fatal("execvp");
1495 }
1496 
1497 static void
1498 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1499 {
1500 	struct gotd_child_proc *proc = &gotd.listen_proc;
1501 
1502 	proc->type = PROC_LISTEN;
1503 
1504 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1505 	    PF_UNSPEC, proc->pipe) == -1)
1506 		fatal("socketpair");
1507 
1508 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1509 	    proc->pipe[1], daemonize, verbosity);
1510 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1511 	proc->iev.handler = gotd_dispatch_listener;
1512 	proc->iev.events = EV_READ;
1513 	proc->iev.handler_arg = NULL;
1514 }
1515 
1516 static const struct got_error *
1517 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1518     char *argv0, const char *confpath, int daemonize, int verbosity)
1519 {
1520 	struct gotd_child_proc *proc;
1521 
1522 	proc = calloc(1, sizeof(*proc));
1523 	if (proc == NULL)
1524 		return got_error_from_errno("calloc");
1525 
1526 	proc->type = PROC_SESSION;
1527 	if (strlcpy(proc->repo_name, repo->name,
1528 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1529 		fatalx("repository name too long: %s", repo->name);
1530 	log_debug("starting client uid %d session for repository %s",
1531 	    client->euid, repo->name);
1532 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1533 	    sizeof(proc->repo_path))
1534 		fatalx("repository path too long: %s", repo->path);
1535 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1536 	    PF_UNSPEC, proc->pipe) == -1)
1537 		fatal("socketpair");
1538 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1539 	    confpath, proc->pipe[1], daemonize, verbosity);
1540 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1541 	log_debug("proc %s %s is on fd %d",
1542 	    gotd_proc_names[proc->type], proc->repo_path,
1543 	    proc->pipe[0]);
1544 	proc->iev.handler = gotd_dispatch_client_session;
1545 	proc->iev.events = EV_READ;
1546 	proc->iev.handler_arg = NULL;
1547 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1548 	    gotd_dispatch_client_session, &proc->iev);
1549 	gotd_imsg_event_add(&proc->iev);
1550 
1551 	client->session = proc;
1552 	return NULL;
1553 }
1554 
1555 static const struct got_error *
1556 start_repo_child(struct gotd_client *client, enum gotd_procid proc_type,
1557     struct gotd_repo *repo, char *argv0, const char *confpath,
1558     int daemonize, int verbosity)
1559 {
1560 	struct gotd_child_proc *proc;
1561 
1562 	if (proc_type != PROC_REPO_READ && proc_type != PROC_REPO_WRITE)
1563 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad process type");
1564 
1565 	proc = calloc(1, sizeof(*proc));
1566 	if (proc == NULL)
1567 		return got_error_from_errno("calloc");
1568 
1569 	proc->type = proc_type;
1570 	if (strlcpy(proc->repo_name, repo->name,
1571 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1572 		fatalx("repository name too long: %s", repo->name);
1573 	log_debug("starting %s for repository %s",
1574 	    proc->type == PROC_REPO_READ ? "reader" : "writer", repo->name);
1575 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1576 	    sizeof(proc->repo_path))
1577 		fatalx("repository path too long: %s", repo->path);
1578 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1579 	    PF_UNSPEC, proc->pipe) == -1)
1580 		fatal("socketpair");
1581 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1582 	    confpath, proc->pipe[1], daemonize, verbosity);
1583 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1584 	log_debug("proc %s %s is on fd %d",
1585 	    gotd_proc_names[proc->type], proc->repo_path,
1586 	    proc->pipe[0]);
1587 	proc->iev.handler = gotd_dispatch_repo_child;
1588 	proc->iev.events = EV_READ;
1589 	proc->iev.handler_arg = NULL;
1590 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1591 	    gotd_dispatch_repo_child, &proc->iev);
1592 	gotd_imsg_event_add(&proc->iev);
1593 
1594 	client->repo = proc;
1595 	return NULL;
1596 }
1597 
1598 static const struct got_error *
1599 start_auth_child(struct gotd_client *client, int required_auth,
1600     struct gotd_repo *repo, char *argv0, const char *confpath,
1601     int daemonize, int verbosity)
1602 {
1603 	const struct got_error *err = NULL;
1604 	struct gotd_child_proc *proc;
1605 	struct gotd_imsg_auth iauth;
1606 	int fd;
1607 
1608 	memset(&iauth, 0, sizeof(iauth));
1609 
1610 	fd = dup(client->fd);
1611 	if (fd == -1)
1612 		return got_error_from_errno("dup");
1613 
1614 	proc = calloc(1, sizeof(*proc));
1615 	if (proc == NULL) {
1616 		err = got_error_from_errno("calloc");
1617 		close(fd);
1618 		return err;
1619 	}
1620 
1621 	proc->type = PROC_AUTH;
1622 	if (strlcpy(proc->repo_name, repo->name,
1623 	    sizeof(proc->repo_name)) >= sizeof(proc->repo_name))
1624 		fatalx("repository name too long: %s", repo->name);
1625 	log_debug("starting auth for uid %d repository %s",
1626 	    client->euid, repo->name);
1627 	if (strlcpy(proc->repo_path, repo->path, sizeof(proc->repo_path)) >=
1628 	    sizeof(proc->repo_path))
1629 		fatalx("repository path too long: %s", repo->path);
1630 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1631 	    PF_UNSPEC, proc->pipe) == -1)
1632 		fatal("socketpair");
1633 	proc->pid = start_child(proc->type, proc->repo_path, argv0,
1634 	    confpath, proc->pipe[1], daemonize, verbosity);
1635 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1636 	log_debug("proc %s %s is on fd %d",
1637 	    gotd_proc_names[proc->type], proc->repo_path,
1638 	    proc->pipe[0]);
1639 	proc->iev.handler = gotd_dispatch_auth_child;
1640 	proc->iev.events = EV_READ;
1641 	proc->iev.handler_arg = NULL;
1642 	event_set(&proc->iev.ev, proc->iev.ibuf.fd, EV_READ,
1643 	    gotd_dispatch_auth_child, &proc->iev);
1644 	gotd_imsg_event_add(&proc->iev);
1645 
1646 	iauth.euid = client->euid;
1647 	iauth.egid = client->egid;
1648 	iauth.required_auth = required_auth;
1649 	iauth.client_id = client->id;
1650 	if (gotd_imsg_compose_event(&proc->iev, GOTD_IMSG_AUTHENTICATE,
1651 	    PROC_GOTD, fd, &iauth, sizeof(iauth)) == -1) {
1652 		log_warn("imsg compose AUTHENTICATE");
1653 		close(fd);
1654 		/* Let the auth_timeout handler tidy up. */
1655 	}
1656 
1657 	client->auth = proc;
1658 	client->required_auth = required_auth;
1659 	return NULL;
1660 }
1661 
1662 static void
1663 apply_unveil_repo_readonly(const char *repo_path)
1664 {
1665 	if (unveil(repo_path, "r") == -1)
1666 		fatal("unveil %s", repo_path);
1667 
1668 	if (unveil(NULL, NULL) == -1)
1669 		fatal("unveil");
1670 }
1671 
1672 static void
1673 apply_unveil_repo_readwrite(const char *repo_path)
1674 {
1675 	if (unveil(repo_path, "rwc") == -1)
1676 		fatal("unveil %s", repo_path);
1677 
1678 	if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1679 		fatal("unveil %s", GOT_TMPDIR_STR);
1680 
1681 	if (unveil(NULL, NULL) == -1)
1682 		fatal("unveil");
1683 }
1684 
1685 static void
1686 apply_unveil_none(void)
1687 {
1688 	if (unveil("/", "") == -1)
1689 		fatal("unveil");
1690 
1691 	if (unveil(NULL, NULL) == -1)
1692 		fatal("unveil");
1693 }
1694 
1695 static void
1696 apply_unveil_selfexec(void)
1697 {
1698 	if (unveil(gotd.argv0, "x") == -1)
1699 		fatal("unveil %s", gotd.argv0);
1700 
1701 	if (unveil(NULL, NULL) == -1)
1702 		fatal("unveil");
1703 }
1704 
1705 int
1706 main(int argc, char **argv)
1707 {
1708 	const struct got_error *error = NULL;
1709 	int ch, fd = -1, daemonize = 1, verbosity = 0, noaction = 0;
1710 	const char *confpath = GOTD_CONF_PATH;
1711 	char *argv0 = argv[0];
1712 	char title[2048];
1713 	struct passwd *pw = NULL;
1714 	char *repo_path = NULL;
1715 	enum gotd_procid proc_id = PROC_GOTD;
1716 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1717 	int *pack_fds = NULL, *temp_fds = NULL;
1718 
1719 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1720 
1721 	while ((ch = getopt(argc, argv, "Adf:LnP:RSvW")) != -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;
1748 			break;
1749 		case 'v':
1750 			if (verbosity < 3)
1751 				verbosity++;
1752 			break;
1753 		case 'W':
1754 			proc_id = PROC_REPO_WRITE;
1755 			break;
1756 		default:
1757 			usage();
1758 		}
1759 	}
1760 
1761 	argc -= optind;
1762 	argv += optind;
1763 
1764 	if (argc != 0)
1765 		usage();
1766 
1767 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1768 		fatalx("need root privileges");
1769 
1770 	if (parse_config(confpath, proc_id, &gotd) != 0)
1771 		return 1;
1772 
1773 	pw = getpwnam(gotd.user_name);
1774 	if (pw == NULL)
1775 		fatalx("user %s not found", gotd.user_name);
1776 
1777 	if (pw->pw_uid == 0)
1778 		fatalx("cannot run %s as the superuser", getprogname());
1779 
1780 	if (noaction) {
1781 		fprintf(stderr, "configuration OK\n");
1782 		return 0;
1783 	}
1784 
1785 	gotd.argv0 = argv0;
1786 	gotd.daemonize = daemonize;
1787 	gotd.verbosity = verbosity;
1788 	gotd.confpath = confpath;
1789 
1790 	/* Require an absolute path in argv[0] for reliable re-exec. */
1791 	if (!got_path_is_absolute(argv0))
1792 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1793 
1794 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1795 	log_setverbose(verbosity);
1796 
1797 	if (proc_id == PROC_GOTD) {
1798 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1799 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1800 		if (daemonize && daemon(1, 0) == -1)
1801 			fatal("daemon");
1802 		gotd.pid = getpid();
1803 		start_listener(argv0, confpath, daemonize, verbosity);
1804 	} else if (proc_id == PROC_LISTEN) {
1805 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1806 		if (verbosity) {
1807 			log_info("socket: %s", gotd.unix_socket_path);
1808 			log_info("user: %s", pw->pw_name);
1809 		}
1810 
1811 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1812 		    pw->pw_gid);
1813 		if (fd == -1) {
1814 			fatal("cannot listen on unix socket %s",
1815 			    gotd.unix_socket_path);
1816 		}
1817 	} else if (proc_id == PROC_AUTH) {
1818 		snprintf(title, sizeof(title), "%s %s",
1819 		    gotd_proc_names[proc_id], repo_path);
1820 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1821 	    proc_id == PROC_SESSION) {
1822 		error = got_repo_pack_fds_open(&pack_fds);
1823 		if (error != NULL)
1824 			fatalx("cannot open pack tempfiles: %s", error->msg);
1825 		error = got_repo_temp_fds_open(&temp_fds);
1826 		if (error != NULL)
1827 			fatalx("cannot open pack tempfiles: %s", error->msg);
1828 		if (repo_path == NULL)
1829 			fatalx("repository path not specified");
1830 		snprintf(title, sizeof(title), "%s %s",
1831 		    gotd_proc_names[proc_id], repo_path);
1832 	} else
1833 		fatal("invalid process id %d", proc_id);
1834 
1835 	setproctitle("%s", title);
1836 	log_procinit(title);
1837 
1838 	/* Drop root privileges. */
1839 	if (setgid(pw->pw_gid) == -1)
1840 		fatal("setgid %d failed", pw->pw_gid);
1841 	if (setuid(pw->pw_uid) == -1)
1842 		fatal("setuid %d failed", pw->pw_uid);
1843 
1844 	event_init();
1845 
1846 	switch (proc_id) {
1847 	case PROC_GOTD:
1848 #ifndef PROFILE
1849 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1850 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1851 			err(1, "pledge");
1852 #endif
1853 		break;
1854 	case PROC_LISTEN:
1855 #ifndef PROFILE
1856 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1857 			err(1, "pledge");
1858 #endif
1859 		/*
1860 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1861 		 * sockets by revoking all filesystem access via unveil(2).
1862 		 */
1863 		apply_unveil_none();
1864 
1865 		listen_main(title, fd, gotd.connection_limits,
1866 		    gotd.nconnection_limits);
1867 		/* NOTREACHED */
1868 		break;
1869 	case PROC_AUTH:
1870 #ifndef PROFILE
1871 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1872 			err(1, "pledge");
1873 #endif
1874 		/*
1875 		 * We need the "unix" pledge promise for getpeername(2) only.
1876 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1877 		 * filesystem access via unveil(2). Access to password database
1878 		 * files will still work since "getpw" bypasses unveil(2).
1879 		 */
1880 		apply_unveil_none();
1881 
1882 		auth_main(title, &gotd.repos, repo_path);
1883 		/* NOTREACHED */
1884 		break;
1885 	case PROC_SESSION:
1886 #ifndef PROFILE
1887 		/*
1888 		 * The "recvfd" promise is only needed during setup and
1889 		 * will be removed in a later pledge(2) call.
1890 		 */
1891 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1892 		    "unveil", NULL) == -1)
1893 			err(1, "pledge");
1894 #endif
1895 		apply_unveil_repo_readwrite(repo_path);
1896 		session_main(title, repo_path, pack_fds, temp_fds,
1897 		    &gotd.request_timeout);
1898 		/* NOTREACHED */
1899 		break;
1900 	case PROC_REPO_READ:
1901 #ifndef PROFILE
1902 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1903 			err(1, "pledge");
1904 #endif
1905 		apply_unveil_repo_readonly(repo_path);
1906 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1907 		/* NOTREACHED */
1908 		exit(0);
1909 	case PROC_REPO_WRITE:
1910 #ifndef PROFILE
1911 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1912 			err(1, "pledge");
1913 #endif
1914 		apply_unveil_repo_readonly(repo_path);
1915 		repo_write_main(title, repo_path, pack_fds, temp_fds);
1916 		/* NOTREACHED */
1917 		exit(0);
1918 	default:
1919 		fatal("invalid process id %d", proc_id);
1920 	}
1921 
1922 	if (proc_id != PROC_GOTD)
1923 		fatal("invalid process id %d", proc_id);
1924 
1925 	apply_unveil_selfexec();
1926 
1927 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1928 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1929 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1930 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1931 	signal(SIGPIPE, SIG_IGN);
1932 
1933 	signal_add(&evsigint, NULL);
1934 	signal_add(&evsigterm, NULL);
1935 	signal_add(&evsighup, NULL);
1936 	signal_add(&evsigusr1, NULL);
1937 
1938 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1939 
1940 	event_dispatch();
1941 
1942 	free(repo_path);
1943 	gotd_shutdown();
1944 
1945 	return 0;
1946 }