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Date:: Tue Jan 10 17:34:45 2023 UTC
Message:: use just one pointer variable to keep track of a client's repo process ok op@
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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 <signal.h>
35 #include <siphash.h>
36 #include <stdarg.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <syslog.h>
41 #include <unistd.h>
42 
43 #include "got_error.h"
44 #include "got_opentemp.h"
45 #include "got_path.h"
46 #include "got_repository.h"
47 #include "got_object.h"
48 #include "got_reference.h"
49 
50 #include "got_lib_delta.h"
51 #include "got_lib_object.h"
52 #include "got_lib_object_cache.h"
53 #include "got_lib_sha1.h"
54 #include "got_lib_gitproto.h"
55 #include "got_lib_pack.h"
56 #include "got_lib_repository.h"
57 
58 #include "gotd.h"
59 #include "log.h"
60 #include "listen.h"
61 #include "auth.h"
62 #include "session.h"
63 #include "repo_read.h"
64 #include "repo_write.h"
65 
66 #ifndef nitems
67 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
68 #endif
69 
70 enum gotd_client_state {
71 	GOTD_CLIENT_STATE_NEW,
72 	GOTD_CLIENT_STATE_ACCESS_GRANTED,
73 };
74 
75 struct gotd_client {
76 	STAILQ_ENTRY(gotd_client)	 entry;
77 	enum gotd_client_state		 state;
78 	uint32_t			 id;
79 	int				 fd;
80 	struct gotd_imsgev		 iev;
81 	struct event			 tmo;
82 	uid_t				 euid;
83 	gid_t				 egid;
84 	struct gotd_child_proc		*repo;
85 	struct gotd_child_proc		*auth;
86 	struct gotd_child_proc		*session;
87 	int				 required_auth;
88 };
89 STAILQ_HEAD(gotd_clients, gotd_client);
90 
91 static struct gotd_clients gotd_clients[GOTD_CLIENT_TABLE_SIZE];
92 static SIPHASH_KEY clients_hash_key;
93 volatile int client_cnt;
94 static struct timeval auth_timeout = { 5, 0 };
95 static struct gotd gotd;
96 
97 void gotd_sighdlr(int sig, short event, void *arg);
98 static void gotd_shutdown(void);
99 static const struct got_error *start_session_child(struct gotd_client *,
100     struct gotd_repo *, char *, const char *, int, int);
101 static const struct got_error *start_repo_child(struct gotd_client *,
102     enum gotd_procid, struct gotd_repo *, char *, const char *, int, int);
103 static const struct got_error *start_auth_child(struct gotd_client *, int,
104     struct gotd_repo *, char *, const char *, int, int);
105 static void kill_proc(struct gotd_child_proc *, int);
106 
107 __dead static void
108 usage()
109 {
110 	fprintf(stderr, "usage: %s [-dv] [-f config-file]\n", getprogname());
111 	exit(1);
112 }
113 
114 static int
115 unix_socket_listen(const char *unix_socket_path, uid_t uid, gid_t gid)
116 {
117 	struct sockaddr_un sun;
118 	int fd = -1;
119 	mode_t old_umask, mode;
120 
121 	fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
122 	if (fd == -1) {
123 		log_warn("socket");
124 		return -1;
125 	}
126 
127 	sun.sun_family = AF_UNIX;
128 	if (strlcpy(sun.sun_path, unix_socket_path,
129 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
130 		log_warnx("%s: name too long", unix_socket_path);
131 		close(fd);
132 		return -1;
133 	}
134 
135 	if (unlink(unix_socket_path) == -1) {
136 		if (errno != ENOENT) {
137 			log_warn("unlink %s", unix_socket_path);
138 			close(fd);
139 			return -1;
140 		}
141 	}
142 
143 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
144 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH;
145 
146 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
147 		log_warn("bind: %s", unix_socket_path);
148 		close(fd);
149 		umask(old_umask);
150 		return -1;
151 	}
152 
153 	umask(old_umask);
154 
155 	if (chmod(unix_socket_path, mode) == -1) {
156 		log_warn("chmod %o %s", mode, unix_socket_path);
157 		close(fd);
158 		unlink(unix_socket_path);
159 		return -1;
160 	}
161 
162 	if (chown(unix_socket_path, uid, gid) == -1) {
163 		log_warn("chown %s uid=%d gid=%d", unix_socket_path, uid, gid);
164 		close(fd);
165 		unlink(unix_socket_path);
166 		return -1;
167 	}
168 
169 	if (listen(fd, GOTD_UNIX_SOCKET_BACKLOG) == -1) {
170 		log_warn("listen");
171 		close(fd);
172 		unlink(unix_socket_path);
173 		return -1;
174 	}
175 
176 	return fd;
177 }
178 
179 static uint64_t
180 client_hash(uint32_t client_id)
181 {
182 	return SipHash24(&clients_hash_key, &client_id, sizeof(client_id));
183 }
184 
185 static void
186 add_client(struct gotd_client *client)
187 {
188 	uint64_t slot = client_hash(client->id) % nitems(gotd_clients);
189 	STAILQ_INSERT_HEAD(&gotd_clients[slot], client, entry);
190 	client_cnt++;
191 }
192 
193 static struct gotd_client *
194 find_client(uint32_t client_id)
195 {
196 	uint64_t slot;
197 	struct gotd_client *c;
198 
199 	slot = client_hash(client_id) % nitems(gotd_clients);
200 	STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
201 		if (c->id == client_id)
202 			return c;
203 	}
204 
205 	return NULL;
206 }
207 
208 static struct gotd_client *
209 find_client_by_proc_fd(int fd)
210 {
211 	uint64_t slot;
212 
213 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
214 		struct gotd_client *c;
215 
216 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
217 			if (c->repo && c->repo->iev.ibuf.fd == fd)
218 				return c;
219 			if (c->auth && c->auth->iev.ibuf.fd == fd)
220 				return c;
221 			if (c->session && c->session->iev.ibuf.fd == fd)
222 				return c;
223 		}
224 	}
225 
226 	return NULL;
227 }
228 
229 static int
230 client_is_reading(struct gotd_client *client)
231 {
232 	return (client->required_auth &
233 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) == GOTD_AUTH_READ;
234 }
235 
236 static int
237 client_is_writing(struct gotd_client *client)
238 {
239 	return (client->required_auth &
240 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE)) ==
241 	    (GOTD_AUTH_READ | GOTD_AUTH_WRITE);
242 }
243 
244 static const struct got_error *
245 ensure_client_is_not_writing(struct gotd_client *client)
246 {
247 	if (client_is_writing(client)) {
248 		return got_error_fmt(GOT_ERR_BAD_PACKET,
249 		    "uid %d made a read-request but is writing to "
250 		    "a repository", client->euid);
251 	}
252 
253 	return NULL;
254 }
255 
256 static const struct got_error *
257 ensure_client_is_not_reading(struct gotd_client *client)
258 {
259 	if (client_is_reading(client)) {
260 		return got_error_fmt(GOT_ERR_BAD_PACKET,
261 		    "uid %d made a write-request but is reading from "
262 		    "a repository", client->euid);
263 	}
264 
265 	return NULL;
266 }
267 
268 static void
269 wait_for_child(pid_t child_pid)
270 {
271 	pid_t pid;
272 	int status;
273 
274 	log_debug("waiting for child PID %ld to terminate",
275 	    (long)child_pid);
276 
277 	do {
278 		pid = waitpid(child_pid, &status, WNOHANG);
279 		if (pid == -1) {
280 			if (errno != EINTR && errno != ECHILD)
281 				fatal("wait");
282 		} else if (WIFSIGNALED(status)) {
283 			log_warnx("child PID %ld terminated; signal %d",
284 			    (long)pid, WTERMSIG(status));
285 		}
286 	} while (pid != -1 || (pid == -1 && errno == EINTR));
287 }
288 
289 static void
290 proc_done(struct gotd_child_proc *proc)
291 {
292 	event_del(&proc->iev.ev);
293 	msgbuf_clear(&proc->iev.ibuf.w);
294 	close(proc->iev.ibuf.fd);
295 	kill_proc(proc, 0);
296 	wait_for_child(proc->pid);
297 	free(proc);
298 }
299 
300 static void
301 kill_auth_proc(struct gotd_client *client)
302 {
303 	struct gotd_child_proc *proc;
304 
305 	if (client->auth == NULL)
306 		return;
307 
308 	proc = client->auth;
309 	client->auth = NULL;
310 
311 	proc_done(proc);
312 }
313 
314 static void
315 kill_session_proc(struct gotd_client *client)
316 {
317 	struct gotd_child_proc *proc;
318 
319 	if (client->session == NULL)
320 		return;
321 
322 	proc = client->session;
323 	client->session = NULL;
324 
325 	proc_done(proc);
326 }
327 
328 static void
329 disconnect(struct gotd_client *client)
330 {
331 	struct gotd_imsg_disconnect idisconnect;
332 	struct gotd_child_proc *proc = client->repo;
333 	struct gotd_child_proc *listen_proc = &gotd.listen_proc;
334 	uint64_t slot;
335 
336 	log_debug("uid %d: disconnecting", client->euid);
337 
338 	kill_auth_proc(client);
339 	kill_session_proc(client);
340 
341 	idisconnect.client_id = client->id;
342 	if (proc) {
343 		if (gotd_imsg_compose_event(&proc->iev,
344 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
345 		    &idisconnect, sizeof(idisconnect)) == -1)
346 			log_warn("imsg compose DISCONNECT");
347 
348 		msgbuf_clear(&proc->iev.ibuf.w);
349 		close(proc->iev.ibuf.fd);
350 		kill_proc(proc, 0);
351 		wait_for_child(proc->pid);
352 		free(proc);
353 		proc = NULL;
354 	}
355 
356 	if (gotd_imsg_compose_event(&listen_proc->iev,
357 	    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
358 	    &idisconnect, sizeof(idisconnect)) == -1)
359 		log_warn("imsg compose DISCONNECT");
360 
361 	slot = client_hash(client->id) % nitems(gotd_clients);
362 	STAILQ_REMOVE(&gotd_clients[slot], client, gotd_client, entry);
363 	imsg_clear(&client->iev.ibuf);
364 	event_del(&client->iev.ev);
365 	evtimer_del(&client->tmo);
366 	if (client->fd != -1)
367 		close(client->fd);
368 	else if (client->iev.ibuf.fd != -1)
369 		close(client->iev.ibuf.fd);
370 	free(client);
371 	client_cnt--;
372 }
373 
374 static void
375 disconnect_on_error(struct gotd_client *client, const struct got_error *err)
376 {
377 	struct imsgbuf ibuf;
378 
379 	log_warnx("uid %d: %s", client->euid, err->msg);
380 	if (err->code != GOT_ERR_EOF && client->fd != -1) {
381 		imsg_init(&ibuf, client->fd);
382 		gotd_imsg_send_error(&ibuf, 0, PROC_GOTD, err);
383 		imsg_clear(&ibuf);
384 	}
385 	disconnect(client);
386 }
387 
388 static const struct got_error *
389 send_repo_info(struct gotd_imsgev *iev, struct gotd_repo *repo)
390 {
391 	const struct got_error *err = NULL;
392 	struct gotd_imsg_info_repo irepo;
393 
394 	memset(&irepo, 0, sizeof(irepo));
395 
396 	if (strlcpy(irepo.repo_name, repo->name, sizeof(irepo.repo_name))
397 	    >= sizeof(irepo.repo_name))
398 		return got_error_msg(GOT_ERR_NO_SPACE, "repo name too long");
399 	if (strlcpy(irepo.repo_path, repo->path, sizeof(irepo.repo_path))
400 	    >= sizeof(irepo.repo_path))
401 		return got_error_msg(GOT_ERR_NO_SPACE, "repo path too long");
402 
403 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_REPO, PROC_GOTD, -1,
404 	    &irepo, sizeof(irepo)) == -1) {
405 		err = got_error_from_errno("imsg compose INFO_REPO");
406 		if (err)
407 			return err;
408 	}
409 
410 	return NULL;
411 }
412 
413 static const struct got_error *
414 send_client_info(struct gotd_imsgev *iev, struct gotd_client *client)
415 {
416 	const struct got_error *err = NULL;
417 	struct gotd_imsg_info_client iclient;
418 	struct gotd_child_proc *proc;
419 
420 	memset(&iclient, 0, sizeof(iclient));
421 	iclient.euid = client->euid;
422 	iclient.egid = client->egid;
423 
424 	proc = client->repo;
425 	if (proc) {
426 		if (strlcpy(iclient.repo_name, proc->repo_path,
427 		    sizeof(iclient.repo_name)) >= sizeof(iclient.repo_name)) {
428 			return got_error_msg(GOT_ERR_NO_SPACE,
429 			    "repo name too long");
430 		}
431 		if (client_is_writing(client))
432 			iclient.is_writing = 1;
433 
434 		iclient.repo_child_pid = proc->pid;
435 	}
436 
437 	if (client->session)
438 		iclient.session_child_pid = client->session->pid;
439 
440 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_INFO_CLIENT, PROC_GOTD, -1,
441 	    &iclient, sizeof(iclient)) == -1) {
442 		err = got_error_from_errno("imsg compose INFO_CLIENT");
443 		if (err)
444 			return err;
445 	}
446 
447 	return NULL;
448 }
449 
450 static const struct got_error *
451 send_info(struct gotd_client *client)
452 {
453 	const struct got_error *err = NULL;
454 	struct gotd_imsg_info info;
455 	uint64_t slot;
456 	struct gotd_repo *repo;
457 
458 	if (client->euid != 0)
459 		return got_error_set_errno(EPERM, "info");
460 
461 	info.pid = gotd.pid;
462 	info.verbosity = gotd.verbosity;
463 	info.nrepos = gotd.nrepos;
464 	info.nclients = client_cnt - 1;
465 
466 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_INFO, PROC_GOTD, -1,
467 	    &info, sizeof(info)) == -1) {
468 		err = got_error_from_errno("imsg compose INFO");
469 		if (err)
470 			return err;
471 	}
472 
473 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
474 		err = send_repo_info(&client->iev, repo);
475 		if (err)
476 			return err;
477 	}
478 
479 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
480 		struct gotd_client *c;
481 		STAILQ_FOREACH(c, &gotd_clients[slot], entry) {
482 			if (c->id == client->id)
483 				continue;
484 			err = send_client_info(&client->iev, c);
485 			if (err)
486 				return err;
487 		}
488 	}
489 
490 	return NULL;
491 }
492 
493 static const struct got_error *
494 stop_gotd(struct gotd_client *client)
495 {
496 
497 	if (client->euid != 0)
498 		return got_error_set_errno(EPERM, "stop");
499 
500 	gotd_shutdown();
501 	/* NOTREACHED */
502 	return NULL;
503 }
504 
505 static struct gotd_repo *
506 find_repo_by_name(const char *repo_name)
507 {
508 	struct gotd_repo *repo;
509 	size_t namelen;
510 
511 	TAILQ_FOREACH(repo, &gotd.repos, entry) {
512 		namelen = strlen(repo->name);
513 		if (strncmp(repo->name, repo_name, namelen) != 0)
514 			continue;
515 		if (repo_name[namelen] == '\0' ||
516 		    strcmp(&repo_name[namelen], ".git") == 0)
517 			return repo;
518 	}
519 
520 	return NULL;
521 }
522 
523 static const struct got_error *
524 start_client_authentication(struct gotd_client *client, struct imsg *imsg)
525 {
526 	const struct got_error *err;
527 	struct gotd_imsg_list_refs ireq;
528 	struct gotd_repo *repo = NULL;
529 	size_t datalen;
530 
531 	log_debug("list-refs request from uid %d", client->euid);
532 
533 	if (client->state != GOTD_CLIENT_STATE_NEW)
534 		return got_error_msg(GOT_ERR_BAD_REQUEST,
535 		    "unexpected list-refs request received");
536 
537 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
538 	if (datalen != sizeof(ireq))
539 		return got_error(GOT_ERR_PRIVSEP_LEN);
540 
541 	memcpy(&ireq, imsg->data, datalen);
542 
543 	if (ireq.client_is_reading) {
544 		err = ensure_client_is_not_writing(client);
545 		if (err)
546 			return err;
547 		repo = find_repo_by_name(ireq.repo_name);
548 		if (repo == NULL)
549 			return got_error(GOT_ERR_NOT_GIT_REPO);
550 		err = start_auth_child(client, GOTD_AUTH_READ, repo,
551 		    gotd.argv0, gotd.confpath, gotd.daemonize,
552 		    gotd.verbosity);
553 		if (err)
554 			return err;
555 	} else {
556 		err = ensure_client_is_not_reading(client);
557 		if (err)
558 			return err;
559 		repo = find_repo_by_name(ireq.repo_name);
560 		if (repo == NULL)
561 			return got_error(GOT_ERR_NOT_GIT_REPO);
562 		err = start_auth_child(client,
563 		    GOTD_AUTH_READ | GOTD_AUTH_WRITE,
564 		    repo, gotd.argv0, gotd.confpath, gotd.daemonize,
565 		    gotd.verbosity);
566 		if (err)
567 			return err;
568 	}
569 
570 	evtimer_add(&client->tmo, &auth_timeout);
571 
572 	/* Flow continues upon authentication successs/failure or timeout. */
573 	return NULL;
574 }
575 
576 static void
577 gotd_request(int fd, short events, void *arg)
578 {
579 	struct gotd_imsgev *iev = arg;
580 	struct imsgbuf *ibuf = &iev->ibuf;
581 	struct gotd_client *client = iev->handler_arg;
582 	const struct got_error *err = NULL;
583 	struct imsg imsg;
584 	ssize_t n;
585 
586 	if (events & EV_WRITE) {
587 		while (ibuf->w.queued) {
588 			n = msgbuf_write(&ibuf->w);
589 			if (n == -1 && errno == EPIPE) {
590 				/*
591 				 * The client has closed its socket.
592 				 * This can happen when Git clients are
593 				 * done sending pack file data.
594 				 */
595 				msgbuf_clear(&ibuf->w);
596 				continue;
597 			} else if (n == -1 && errno != EAGAIN) {
598 				err = got_error_from_errno("imsg_flush");
599 				disconnect_on_error(client, err);
600 				return;
601 			}
602 			if (n == 0) {
603 				/* Connection closed. */
604 				err = got_error(GOT_ERR_EOF);
605 				disconnect_on_error(client, err);
606 				return;
607 			}
608 		}
609 
610 		/* Disconnect gotctl(8) now that messages have been sent. */
611 		if (!client_is_reading(client) && !client_is_writing(client)) {
612 			disconnect(client);
613 			return;
614 		}
615 	}
616 
617 	if ((events & EV_READ) == 0)
618 		return;
619 
620 	memset(&imsg, 0, sizeof(imsg));
621 
622 	while (err == NULL) {
623 		err = gotd_imsg_recv(&imsg, ibuf, 0);
624 		if (err) {
625 			if (err->code == GOT_ERR_PRIVSEP_READ)
626 				err = NULL;
627 			break;
628 		}
629 
630 		evtimer_del(&client->tmo);
631 
632 		switch (imsg.hdr.type) {
633 		case GOTD_IMSG_INFO:
634 			err = send_info(client);
635 			break;
636 		case GOTD_IMSG_STOP:
637 			err = stop_gotd(client);
638 			break;
639 		case GOTD_IMSG_LIST_REFS:
640 			err = start_client_authentication(client, &imsg);
641 			break;
642 		default:
643 			log_debug("unexpected imsg %d", imsg.hdr.type);
644 			err = got_error(GOT_ERR_PRIVSEP_MSG);
645 			break;
646 		}
647 
648 		imsg_free(&imsg);
649 	}
650 
651 	if (err) {
652 		if (err->code != GOT_ERR_EOF)
653 			disconnect_on_error(client, err);
654 	} else {
655 		gotd_imsg_event_add(&client->iev);
656 	}
657 }
658 
659 static void
660 gotd_auth_timeout(int fd, short events, void *arg)
661 {
662 	struct gotd_client *client = arg;
663 
664 	log_debug("disconnecting uid %d due to authentication timeout",
665 	    client->euid);
666 	disconnect(client);
667 }
668 
669 static const struct got_error *
670 recv_connect(uint32_t *client_id, struct imsg *imsg)
671 {
672 	const struct got_error *err = NULL;
673 	struct gotd_imsg_connect iconnect;
674 	size_t datalen;
675 	int s = -1;
676 	struct gotd_client *client = NULL;
677 
678 	*client_id = 0;
679 
680 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
681 	if (datalen != sizeof(iconnect))
682 		return got_error(GOT_ERR_PRIVSEP_LEN);
683 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
684 
685 	s = imsg->fd;
686 	if (s == -1) {
687 		err = got_error(GOT_ERR_PRIVSEP_NO_FD);
688 		goto done;
689 	}
690 
691 	if (find_client(iconnect.client_id)) {
692 		err = got_error_msg(GOT_ERR_CLIENT_ID, "duplicate client ID");
693 		goto done;
694 	}
695 
696 	client = calloc(1, sizeof(*client));
697 	if (client == NULL) {
698 		err = got_error_from_errno("calloc");
699 		goto done;
700 	}
701 
702 	*client_id = iconnect.client_id;
703 
704 	client->state = GOTD_CLIENT_STATE_NEW;
705 	client->id = iconnect.client_id;
706 	client->fd = s;
707 	s = -1;
708 	/* The auth process will verify UID/GID for us. */
709 	client->euid = iconnect.euid;
710 	client->egid = iconnect.egid;
711 
712 	imsg_init(&client->iev.ibuf, client->fd);
713 	client->iev.handler = gotd_request;
714 	client->iev.events = EV_READ;
715 	client->iev.handler_arg = client;
716 
717 	event_set(&client->iev.ev, client->fd, EV_READ, gotd_request,
718 	    &client->iev);
719 	gotd_imsg_event_add(&client->iev);
720 
721 	evtimer_set(&client->tmo, gotd_auth_timeout, client);
722 
723 	add_client(client);
724 	log_debug("%s: new client uid %d connected on fd %d", __func__,
725 	    client->euid, client->fd);
726 done:
727 	if (err) {
728 		struct gotd_child_proc *listen_proc = &gotd.listen_proc;
729 		struct gotd_imsg_disconnect idisconnect;
730 
731 		idisconnect.client_id = client->id;
732 		if (gotd_imsg_compose_event(&listen_proc->iev,
733 		    GOTD_IMSG_DISCONNECT, PROC_GOTD, -1,
734 		    &idisconnect, sizeof(idisconnect)) == -1)
735 			log_warn("imsg compose DISCONNECT");
736 
737 		if (s != -1)
738 			close(s);
739 	}
740 
741 	return err;
742 }
743 
744 static const char *gotd_proc_names[PROC_MAX] = {
745 	"parent",
746 	"listen",
747 	"auth",
748 	"session",
749 	"repo_read",
750 	"repo_write"
751 };
752 
753 static void
754 kill_proc(struct gotd_child_proc *proc, int fatal)
755 {
756 	if (fatal) {
757 		log_warnx("sending SIGKILL to PID %d", proc->pid);
758 		kill(proc->pid, SIGKILL);
759 	} else
760 		kill(proc->pid, SIGTERM);
761 }
762 
763 static void
764 gotd_shutdown(void)
765 {
766 	struct gotd_child_proc *proc;
767 	uint64_t slot;
768 
769 	log_debug("shutting down");
770 	for (slot = 0; slot < nitems(gotd_clients); slot++) {
771 		struct gotd_client *c, *tmp;
772 
773 		STAILQ_FOREACH_SAFE(c, &gotd_clients[slot], entry, tmp)
774 			disconnect(c);
775 	}
776 
777 	proc = &gotd.listen_proc;
778 	msgbuf_clear(&proc->iev.ibuf.w);
779 	close(proc->iev.ibuf.fd);
780 	kill_proc(proc, 0);
781 	wait_for_child(proc->pid);
782 
783 	log_info("terminating");
784 	exit(0);
785 }
786 
787 void
788 gotd_sighdlr(int sig, short event, void *arg)
789 {
790 	/*
791 	 * Normal signal handler rules don't apply because libevent
792 	 * decouples for us.
793 	 */
794 
795 	switch (sig) {
796 	case SIGHUP:
797 		log_info("%s: ignoring SIGHUP", __func__);
798 		break;
799 	case SIGUSR1:
800 		log_info("%s: ignoring SIGUSR1", __func__);
801 		break;
802 	case SIGTERM:
803 	case SIGINT:
804 		gotd_shutdown();
805 		break;
806 	default:
807 		fatalx("unexpected signal");
808 	}
809 }
810 
811 static const struct got_error *
812 ensure_proc_is_reading(struct gotd_client *client,
813     struct gotd_child_proc *proc)
814 {
815 	if (!client_is_reading(client)) {
816 		kill_proc(proc, 1);
817 		return got_error_fmt(GOT_ERR_BAD_PACKET,
818 		    "PID %d handled a read-request for uid %d but this "
819 		    "user is not reading from a repository", proc->pid,
820 		    client->euid);
821 	}
822 
823 	return NULL;
824 }
825 
826 static const struct got_error *
827 ensure_proc_is_writing(struct gotd_client *client,
828     struct gotd_child_proc *proc)
829 {
830 	if (!client_is_writing(client)) {
831 		kill_proc(proc, 1);
832 		return got_error_fmt(GOT_ERR_BAD_PACKET,
833 		    "PID %d handled a write-request for uid %d but this "
834 		    "user is not writing to a repository", proc->pid,
835 		    client->euid);
836 	}
837 
838 	return NULL;
839 }
840 
841 static int
842 verify_imsg_src(struct gotd_client *client, struct gotd_child_proc *proc,
843     struct imsg *imsg)
844 {
845 	const struct got_error *err;
846 	int ret = 0;
847 
848 	if (proc->type == PROC_REPO_READ || proc->type == PROC_REPO_WRITE) {
849 		if (client->repo == NULL)
850 			fatalx("no process found for uid %d", client->euid);
851 		if (proc->pid != client->repo->pid) {
852 			kill_proc(proc, 1);
853 			log_warnx("received message from PID %d for uid %d, "
854 			    "while PID %d is the process serving this user",
855 			    proc->pid, client->euid, client->repo->pid);
856 			return 0;
857 		}
858 	}
859 	if (proc->type == PROC_SESSION) {
860 		if (client->session == NULL) {
861 			log_warnx("no session found for uid %d", client->euid);
862 			return 0;
863 		}
864 		if (proc->pid != client->session->pid) {
865 			kill_proc(proc, 1);
866 			log_warnx("received message from PID %d for uid %d, "
867 			    "while PID %d is the process serving this user",
868 			    proc->pid, client->euid, client->session->pid);
869 			return 0;
870 		}
871 	}
872 
873 	switch (imsg->hdr.type) {
874 	case GOTD_IMSG_ERROR:
875 		ret = 1;
876 		break;
877 	case GOTD_IMSG_CONNECT:
878 		if (proc->type != PROC_LISTEN) {
879 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
880 			    "new connection for uid %d from PID %d "
881 			    "which is not the listen process",
882 			    proc->pid, client->euid);
883 		} else
884 			ret = 1;
885 		break;
886 	case GOTD_IMSG_ACCESS_GRANTED:
887 		if (proc->type != PROC_AUTH) {
888 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
889 			    "authentication of uid %d from PID %d "
890 			    "which is not the auth process",
891 			    proc->pid, client->euid);
892 		} else
893 			ret = 1;
894 		break;
895 	case GOTD_IMSG_CLIENT_SESSION_READY:
896 		if (proc->type != PROC_SESSION) {
897 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
898 			    "unexpected \"ready\" signal from PID %d",
899 			    proc->pid);
900 		} else
901 			ret = 1;
902 		break;
903 	case GOTD_IMSG_REPO_CHILD_READY:
904 		if (proc->type != PROC_REPO_READ &&
905 		    proc->type != PROC_REPO_WRITE) {
906 			err = got_error_fmt(GOT_ERR_BAD_PACKET,
907 			    "unexpected \"ready\" signal from PID %d",
908 			    proc->pid);
909 		} else
910 			ret = 1;
911 		break;
912 	case GOTD_IMSG_PACKFILE_DONE:
913 		err = ensure_proc_is_reading(client, proc);
914 		if (err)
915 			log_warnx("uid %d: %s", client->euid, err->msg);
916 		else
917 			ret = 1;
918 		break;
919 	case GOTD_IMSG_PACKFILE_INSTALL:
920 	case GOTD_IMSG_REF_UPDATES_START:
921 	case GOTD_IMSG_REF_UPDATE:
922 		err = ensure_proc_is_writing(client, proc);
923 		if (err)
924 			log_warnx("uid %d: %s", client->euid, err->msg);
925 		else
926 			ret = 1;
927 		break;
928 	default:
929 		log_debug("%s: unexpected imsg %d", __func__, imsg->hdr.type);
930 		break;
931 	}
932 
933 	return ret;
934 }
935 
936 static const struct got_error *
937 connect_repo_child(struct gotd_client *client,
938     struct gotd_child_proc *repo_proc)
939 {
940 	static const struct got_error *err;
941 	struct gotd_imsgev *session_iev = &client->session->iev;
942 	struct gotd_imsg_connect_repo_child ireq;
943 	int pipe[2];
944 
945 	if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED)
946 		return got_error_msg(GOT_ERR_BAD_REQUEST,
947 		    "unexpected repo child ready signal received");
948 
949 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
950 	    PF_UNSPEC, pipe) == -1)
951 		fatal("socketpair");
952 
953 	memset(&ireq, 0, sizeof(ireq));
954 	ireq.client_id = client->id;
955 	ireq.proc_id = repo_proc->type;
956 
957 	/* Pass repo child pipe to session child process. */
958 	if (gotd_imsg_compose_event(session_iev, GOTD_IMSG_CONNECT_REPO_CHILD,
959 	    PROC_GOTD, pipe[0], &ireq, sizeof(ireq)) == -1) {
960 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
961 		close(pipe[0]);
962 		close(pipe[1]);
963 		return err;
964 	}
965 
966 	/* Pass session child pipe to repo child process. */
967 	if (gotd_imsg_compose_event(&repo_proc->iev,
968 	    GOTD_IMSG_CONNECT_REPO_CHILD, PROC_GOTD, pipe[1], NULL, 0) == -1) {
969 		err = got_error_from_errno("imsg compose CONNECT_REPO_CHILD");
970 		close(pipe[1]);
971 		return err;
972 	}
973 
974 	return NULL;
975 }
976 
977 static void
978 gotd_dispatch_listener(int fd, short event, void *arg)
979 {
980 	struct gotd_imsgev *iev = arg;
981 	struct imsgbuf *ibuf = &iev->ibuf;
982 	struct gotd_child_proc *proc = &gotd.listen_proc;
983 	ssize_t n;
984 	int shut = 0;
985 	struct imsg imsg;
986 
987 	if (proc->iev.ibuf.fd != fd)
988 		fatalx("%s: unexpected fd %d", __func__, fd);
989 
990 	if (event & EV_READ) {
991 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
992 			fatal("imsg_read error");
993 		if (n == 0) {
994 			/* Connection closed. */
995 			shut = 1;
996 			goto done;
997 		}
998 	}
999 
1000 	if (event & EV_WRITE) {
1001 		n = msgbuf_write(&ibuf->w);
1002 		if (n == -1 && errno != EAGAIN)
1003 			fatal("msgbuf_write");
1004 		if (n == 0) {
1005 			/* Connection closed. */
1006 			shut = 1;
1007 			goto done;
1008 		}
1009 	}
1010 
1011 	for (;;) {
1012 		const struct got_error *err = NULL;
1013 		struct gotd_client *client = NULL;
1014 		uint32_t client_id = 0;
1015 		int do_disconnect = 0;
1016 
1017 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1018 			fatal("%s: imsg_get error", __func__);
1019 		if (n == 0)	/* No more messages. */
1020 			break;
1021 
1022 		switch (imsg.hdr.type) {
1023 		case GOTD_IMSG_ERROR:
1024 			do_disconnect = 1;
1025 			err = gotd_imsg_recv_error(&client_id, &imsg);
1026 			break;
1027 		case GOTD_IMSG_CONNECT:
1028 			err = recv_connect(&client_id, &imsg);
1029 			break;
1030 		default:
1031 			log_debug("unexpected imsg %d", imsg.hdr.type);
1032 			break;
1033 		}
1034 
1035 		client = find_client(client_id);
1036 		if (client == NULL) {
1037 			log_warnx("%s: client not found", __func__);
1038 			imsg_free(&imsg);
1039 			continue;
1040 		}
1041 
1042 		if (err)
1043 			log_warnx("uid %d: %s", client->euid, err->msg);
1044 
1045 		if (do_disconnect) {
1046 			if (err)
1047 				disconnect_on_error(client, err);
1048 			else
1049 				disconnect(client);
1050 		}
1051 
1052 		imsg_free(&imsg);
1053 	}
1054 done:
1055 	if (!shut) {
1056 		gotd_imsg_event_add(iev);
1057 	} else {
1058 		/* This pipe is dead. Remove its event handler */
1059 		event_del(&iev->ev);
1060 		event_loopexit(NULL);
1061 	}
1062 }
1063 
1064 static void
1065 gotd_dispatch_auth_child(int fd, short event, void *arg)
1066 {
1067 	const struct got_error *err = NULL;
1068 	struct gotd_imsgev *iev = arg;
1069 	struct imsgbuf *ibuf = &iev->ibuf;
1070 	struct gotd_client *client;
1071 	struct gotd_repo *repo = NULL;
1072 	ssize_t n;
1073 	int shut = 0;
1074 	struct imsg imsg;
1075 	uint32_t client_id = 0;
1076 	int do_disconnect = 0;
1077 
1078 	client = find_client_by_proc_fd(fd);
1079 	if (client == NULL)
1080 		fatalx("cannot find client for fd %d", fd);
1081 
1082 	if (client->auth == NULL)
1083 		fatalx("cannot find auth child process for fd %d", fd);
1084 
1085 	if (event & EV_READ) {
1086 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1087 			fatal("imsg_read error");
1088 		if (n == 0) {
1089 			/* Connection closed. */
1090 			shut = 1;
1091 			goto done;
1092 		}
1093 	}
1094 
1095 	if (event & EV_WRITE) {
1096 		n = msgbuf_write(&ibuf->w);
1097 		if (n == -1 && errno != EAGAIN)
1098 			fatal("msgbuf_write");
1099 		if (n == 0) {
1100 			/* Connection closed. */
1101 			shut = 1;
1102 		}
1103 		goto done;
1104 	}
1105 
1106 	if (client->auth->iev.ibuf.fd != fd)
1107 		fatalx("%s: unexpected fd %d", __func__, fd);
1108 
1109 	if ((n = imsg_get(ibuf, &imsg)) == -1)
1110 		fatal("%s: imsg_get error", __func__);
1111 	if (n == 0)	/* No more messages. */
1112 		return;
1113 
1114 	evtimer_del(&client->tmo);
1115 
1116 	switch (imsg.hdr.type) {
1117 	case GOTD_IMSG_ERROR:
1118 		do_disconnect = 1;
1119 		err = gotd_imsg_recv_error(&client_id, &imsg);
1120 		break;
1121 	case GOTD_IMSG_ACCESS_GRANTED:
1122 		client->state = GOTD_CLIENT_STATE_ACCESS_GRANTED;
1123 		break;
1124 	default:
1125 		do_disconnect = 1;
1126 		log_debug("unexpected imsg %d", imsg.hdr.type);
1127 		break;
1128 	}
1129 
1130 	if (!verify_imsg_src(client, client->auth, &imsg)) {
1131 		do_disconnect = 1;
1132 		log_debug("dropping imsg type %d from PID %d",
1133 		    imsg.hdr.type, client->auth->pid);
1134 	}
1135 	imsg_free(&imsg);
1136 
1137 	if (do_disconnect) {
1138 		if (err)
1139 			disconnect_on_error(client, err);
1140 		else
1141 			disconnect(client);
1142 		goto done;
1143 	}
1144 
1145 	repo = find_repo_by_name(client->auth->repo_name);
1146 	if (repo == NULL) {
1147 		err = got_error(GOT_ERR_NOT_GIT_REPO);
1148 		goto done;
1149 	}
1150 	kill_auth_proc(client);
1151 
1152 	log_info("authenticated uid %d for repository %s\n",
1153 	    client->euid, repo->name);
1154 
1155 	err = start_session_child(client, repo, gotd.argv0,
1156 	    gotd.confpath, gotd.daemonize, gotd.verbosity);
1157 	if (err)
1158 		goto done;
1159 done:
1160 	if (err)
1161 		log_warnx("uid %d: %s", client->euid, err->msg);
1162 
1163 	/* We might have killed the auth process by now. */
1164 	if (client->auth != NULL) {
1165 		if (!shut) {
1166 			gotd_imsg_event_add(iev);
1167 		} else {
1168 			/* This pipe is dead. Remove its event handler */
1169 			event_del(&iev->ev);
1170 		}
1171 	}
1172 }
1173 
1174 static const struct got_error *
1175 connect_session(struct gotd_client *client)
1176 {
1177 	const struct got_error *err = NULL;
1178 	struct gotd_imsg_connect iconnect;
1179 	int s;
1180 
1181 	memset(&iconnect, 0, sizeof(iconnect));
1182 
1183 	s = dup(client->fd);
1184 	if (s == -1)
1185 		return got_error_from_errno("dup");
1186 
1187 	iconnect.client_id = client->id;
1188 	iconnect.euid = client->euid;
1189 	iconnect.egid = client->egid;
1190 
1191 	if (gotd_imsg_compose_event(&client->session->iev, GOTD_IMSG_CONNECT,
1192 	    PROC_GOTD, s, &iconnect, sizeof(iconnect)) == -1) {
1193 		err = got_error_from_errno("imsg compose CONNECT");
1194 		close(s);
1195 		return err;
1196 	}
1197 
1198 	/*
1199 	 * We are no longer interested in messages from this client.
1200 	 * Further client requests will be handled by the session process.
1201 	 */
1202 	msgbuf_clear(&client->iev.ibuf.w);
1203 	imsg_clear(&client->iev.ibuf);
1204 	event_del(&client->iev.ev);
1205 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
1206 
1207 	return NULL;
1208 }
1209 
1210 static void
1211 gotd_dispatch_client_session(int fd, short event, void *arg)
1212 {
1213 	struct gotd_imsgev *iev = arg;
1214 	struct imsgbuf *ibuf = &iev->ibuf;
1215 	struct gotd_child_proc *proc = NULL;
1216 	struct gotd_client *client = NULL;
1217 	ssize_t n;
1218 	int shut = 0;
1219 	struct imsg imsg;
1220 
1221 	client = find_client_by_proc_fd(fd);
1222 	if (client == NULL)
1223 		fatalx("cannot find client for fd %d", fd);
1224 
1225 	if (event & EV_READ) {
1226 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1227 			fatal("imsg_read error");
1228 		if (n == 0) {
1229 			/* Connection closed. */
1230 			shut = 1;
1231 			goto done;
1232 		}
1233 	}
1234 
1235 	if (event & EV_WRITE) {
1236 		n = msgbuf_write(&ibuf->w);
1237 		if (n == -1 && errno != EAGAIN)
1238 			fatal("msgbuf_write");
1239 		if (n == 0) {
1240 			/* Connection closed. */
1241 			shut = 1;
1242 			goto done;
1243 		}
1244 	}
1245 
1246 	proc = client->session;
1247 	if (proc == NULL)
1248 		fatalx("cannot find session child process for fd %d", fd);
1249 
1250 	for (;;) {
1251 		const struct got_error *err = NULL;
1252 		uint32_t client_id = 0;
1253 		int do_disconnect = 0, do_start_repo_child = 0;
1254 
1255 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1256 			fatal("%s: imsg_get error", __func__);
1257 		if (n == 0)	/* No more messages. */
1258 			break;
1259 
1260 		switch (imsg.hdr.type) {
1261 		case GOTD_IMSG_ERROR:
1262 			do_disconnect = 1;
1263 			err = gotd_imsg_recv_error(&client_id, &imsg);
1264 			break;
1265 		case GOTD_IMSG_CLIENT_SESSION_READY:
1266 			if (client->state != GOTD_CLIENT_STATE_ACCESS_GRANTED) {
1267 				err = got_error(GOT_ERR_PRIVSEP_MSG);
1268 				break;
1269 			}
1270 			do_start_repo_child = 1;
1271 			break;
1272 		case GOTD_IMSG_DISCONNECT:
1273 			do_disconnect = 1;
1274 			break;
1275 		default:
1276 			log_debug("unexpected imsg %d", imsg.hdr.type);
1277 			break;
1278 		}
1279 
1280 		if (!verify_imsg_src(client, proc, &imsg)) {
1281 			log_debug("dropping imsg type %d from PID %d",
1282 			    imsg.hdr.type, proc->pid);
1283 			imsg_free(&imsg);
1284 			continue;
1285 		}
1286 		if (err)
1287 			log_warnx("uid %d: %s", client->euid, err->msg);
1288 
1289 		if (do_start_repo_child) {
1290 			struct gotd_repo *repo;
1291 
1292 			repo = find_repo_by_name(client->session->repo_name);
1293 			if (repo != NULL) {
1294 				enum gotd_procid proc_type;
1295 
1296 				if (client->required_auth & GOTD_AUTH_WRITE)
1297 					proc_type = PROC_REPO_WRITE;
1298 				else
1299 					proc_type = PROC_REPO_READ;
1300 
1301 				err = start_repo_child(client, proc_type, repo,
1302 				    gotd.argv0, gotd.confpath, gotd.daemonize,
1303 				    gotd.verbosity);
1304 			} else
1305 				err = got_error(GOT_ERR_NOT_GIT_REPO);
1306 
1307 			if (err) {
1308 				log_warnx("uid %d: %s", client->euid, err->msg);
1309 				do_disconnect = 1;
1310 			}
1311 		}
1312 
1313 		if (do_disconnect) {
1314 			if (err)
1315 				disconnect_on_error(client, err);
1316 			else
1317 				disconnect(client);
1318 		}
1319 
1320 		imsg_free(&imsg);
1321 	}
1322 done:
1323 	if (!shut) {
1324 		gotd_imsg_event_add(iev);
1325 	} else {
1326 		/* This pipe is dead. Remove its event handler */
1327 		event_del(&iev->ev);
1328 		disconnect(client);
1329 	}
1330 }
1331 
1332 static void
1333 gotd_dispatch_repo_child(int fd, short event, void *arg)
1334 {
1335 	struct gotd_imsgev *iev = arg;
1336 	struct imsgbuf *ibuf = &iev->ibuf;
1337 	struct gotd_child_proc *proc = NULL;
1338 	struct gotd_client *client;
1339 	ssize_t n;
1340 	int shut = 0;
1341 	struct imsg imsg;
1342 
1343 	client = find_client_by_proc_fd(fd);
1344 	if (client == NULL)
1345 		fatalx("cannot find client for fd %d", fd);
1346 
1347 	if (event & EV_READ) {
1348 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1349 			fatal("imsg_read error");
1350 		if (n == 0) {
1351 			/* Connection closed. */
1352 			shut = 1;
1353 			goto done;
1354 		}
1355 	}
1356 
1357 	if (event & EV_WRITE) {
1358 		n = msgbuf_write(&ibuf->w);
1359 		if (n == -1 && errno != EAGAIN)
1360 			fatal("msgbuf_write");
1361 		if (n == 0) {
1362 			/* Connection closed. */
1363 			shut = 1;
1364 			goto done;
1365 		}
1366 	}
1367 
1368 	proc = client->repo;
1369 	if (proc == NULL)
1370 		fatalx("cannot find child process for fd %d", fd);
1371 
1372 	for (;;) {
1373 		const struct got_error *err = NULL;
1374 		uint32_t client_id = 0;
1375 		int do_disconnect = 0;
1376 
1377 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1378 			fatal("%s: imsg_get error", __func__);
1379 		if (n == 0)	/* No more messages. */
1380 			break;
1381 
1382 		switch (imsg.hdr.type) {
1383 		case GOTD_IMSG_ERROR:
1384 			do_disconnect = 1;
1385 			err = gotd_imsg_recv_error(&client_id, &imsg);
1386 			break;
1387 		case GOTD_IMSG_REPO_CHILD_READY:
1388 			err = connect_session(client);
1389 			if (err)
1390 				break;
1391 			err = connect_repo_child(client, proc);
1392 			break;
1393 		default:
1394 			log_debug("unexpected imsg %d", imsg.hdr.type);
1395 			break;
1396 		}
1397 
1398 		if (!verify_imsg_src(client, proc, &imsg)) {
1399 			log_debug("dropping imsg type %d from PID %d",
1400 			    imsg.hdr.type, proc->pid);
1401 			imsg_free(&imsg);
1402 			continue;
1403 		}
1404 		if (err)
1405 			log_warnx("uid %d: %s", client->euid, err->msg);
1406 
1407 		if (do_disconnect) {
1408 			if (err)
1409 				disconnect_on_error(client, err);
1410 			else
1411 				disconnect(client);
1412 		}
1413 
1414 		imsg_free(&imsg);
1415 	}
1416 done:
1417 	if (!shut) {
1418 		gotd_imsg_event_add(iev);
1419 	} else {
1420 		/* This pipe is dead. Remove its event handler */
1421 		event_del(&iev->ev);
1422 		disconnect(client);
1423 	}
1424 }
1425 
1426 static pid_t
1427 start_child(enum gotd_procid proc_id, const char *repo_path,
1428     char *argv0, const char *confpath, int fd, int daemonize, int verbosity)
1429 {
1430 	char	*argv[11];
1431 	int	 argc = 0;
1432 	pid_t	 pid;
1433 
1434 	switch (pid = fork()) {
1435 	case -1:
1436 		fatal("cannot fork");
1437 	case 0:
1438 		break;
1439 	default:
1440 		close(fd);
1441 		return pid;
1442 	}
1443 
1444 	if (fd != GOTD_FILENO_MSG_PIPE) {
1445 		if (dup2(fd, GOTD_FILENO_MSG_PIPE) == -1)
1446 			fatal("cannot setup imsg fd");
1447 	} else if (fcntl(fd, F_SETFD, 0) == -1)
1448 		fatal("cannot setup imsg fd");
1449 
1450 	argv[argc++] = argv0;
1451 	switch (proc_id) {
1452 	case PROC_LISTEN:
1453 		argv[argc++] = (char *)"-L";
1454 		break;
1455 	case PROC_AUTH:
1456 		argv[argc++] = (char *)"-A";
1457 		break;
1458 	case PROC_SESSION:
1459 		argv[argc++] = (char *)"-S";
1460 		break;
1461 	case PROC_REPO_READ:
1462 		argv[argc++] = (char *)"-R";
1463 		break;
1464 	case PROC_REPO_WRITE:
1465 		argv[argc++] = (char *)"-W";
1466 		break;
1467 	default:
1468 		fatalx("invalid process id %d", proc_id);
1469 	}
1470 
1471 	argv[argc++] = (char *)"-f";
1472 	argv[argc++] = (char *)confpath;
1473 
1474 	if (repo_path) {
1475 		argv[argc++] = (char *)"-P";
1476 		argv[argc++] = (char *)repo_path;
1477 	}
1478 
1479 	if (!daemonize)
1480 		argv[argc++] = (char *)"-d";
1481 	if (verbosity > 0)
1482 		argv[argc++] = (char *)"-v";
1483 	if (verbosity > 1)
1484 		argv[argc++] = (char *)"-v";
1485 	argv[argc++] = NULL;
1486 
1487 	execvp(argv0, argv);
1488 	fatal("execvp");
1489 }
1490 
1491 static void
1492 start_listener(char *argv0, const char *confpath, int daemonize, int verbosity)
1493 {
1494 	struct gotd_child_proc *proc = &gotd.listen_proc;
1495 
1496 	proc->type = PROC_LISTEN;
1497 
1498 	if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK,
1499 	    PF_UNSPEC, proc->pipe) == -1)
1500 		fatal("socketpair");
1501 
1502 	proc->pid = start_child(proc->type, NULL, argv0, confpath,
1503 	    proc->pipe[1], daemonize, verbosity);
1504 	imsg_init(&proc->iev.ibuf, proc->pipe[0]);
1505 	proc->iev.handler = gotd_dispatch_listener;
1506 	proc->iev.events = EV_READ;
1507 	proc->iev.handler_arg = NULL;
1508 }
1509 
1510 static const struct got_error *
1511 start_session_child(struct gotd_client *client, struct gotd_repo *repo,
1512     char *argv0, const char *confpath, int daemonize, int verbosity)
1513 {
1514 	struct gotd_child_proc *proc;
1515 
1516 	proc = calloc(1, sizeof(*proc));
1517 	if (proc == NULL)
1518 		return got_error_from_errno("calloc");
1519 
1520 	proc->type = PROC_SESSION;
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)
1658 {
1659 	if (unveil(repo_path, "r") == -1)
1660 		fatal("unveil %s", repo_path);
1661 
1662 	if (unveil(NULL, NULL) == -1)
1663 		fatal("unveil");
1664 }
1665 
1666 static void
1667 apply_unveil_repo_readwrite(const char *repo_path)
1668 {
1669 	if (unveil(repo_path, "rwc") == -1)
1670 		fatal("unveil %s", repo_path);
1671 
1672 	if (unveil(GOT_TMPDIR_STR, "rwc") == -1)
1673 		fatal("unveil %s", GOT_TMPDIR_STR);
1674 
1675 	if (unveil(NULL, NULL) == -1)
1676 		fatal("unveil");
1677 }
1678 
1679 static void
1680 apply_unveil_none(void)
1681 {
1682 	if (unveil("/", "") == -1)
1683 		fatal("unveil");
1684 
1685 	if (unveil(NULL, NULL) == -1)
1686 		fatal("unveil");
1687 }
1688 
1689 static void
1690 apply_unveil_selfexec(void)
1691 {
1692 	if (unveil(gotd.argv0, "x") == -1)
1693 		fatal("unveil %s", gotd.argv0);
1694 
1695 	if (unveil(NULL, NULL) == -1)
1696 		fatal("unveil");
1697 }
1698 
1699 int
1700 main(int argc, char **argv)
1701 {
1702 	const struct got_error *error = NULL;
1703 	int ch, fd = -1, daemonize = 1, verbosity = 0, noaction = 0;
1704 	const char *confpath = GOTD_CONF_PATH;
1705 	char *argv0 = argv[0];
1706 	char title[2048];
1707 	struct passwd *pw = NULL;
1708 	char *repo_path = NULL;
1709 	enum gotd_procid proc_id = PROC_GOTD;
1710 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1711 	int *pack_fds = NULL, *temp_fds = NULL;
1712 
1713 	log_init(1, LOG_DAEMON); /* Log to stderr until daemonized. */
1714 
1715 	while ((ch = getopt(argc, argv, "Adf:LnP:RSvW")) != -1) {
1716 		switch (ch) {
1717 		case 'A':
1718 			proc_id = PROC_AUTH;
1719 			break;
1720 		case 'd':
1721 			daemonize = 0;
1722 			break;
1723 		case 'f':
1724 			confpath = optarg;
1725 			break;
1726 		case 'L':
1727 			proc_id = PROC_LISTEN;
1728 			break;
1729 		case 'n':
1730 			noaction = 1;
1731 			break;
1732 		case 'P':
1733 			repo_path = realpath(optarg, NULL);
1734 			if (repo_path == NULL)
1735 				fatal("realpath '%s'", optarg);
1736 			break;
1737 		case 'R':
1738 			proc_id = PROC_REPO_READ;
1739 			break;
1740 		case 'S':
1741 			proc_id = PROC_SESSION;
1742 			break;
1743 		case 'v':
1744 			if (verbosity < 3)
1745 				verbosity++;
1746 			break;
1747 		case 'W':
1748 			proc_id = PROC_REPO_WRITE;
1749 			break;
1750 		default:
1751 			usage();
1752 		}
1753 	}
1754 
1755 	argc -= optind;
1756 	argv += optind;
1757 
1758 	if (argc != 0)
1759 		usage();
1760 
1761 	/* Require an absolute path in argv[0] for reliable re-exec. */
1762 	if (!got_path_is_absolute(argv0))
1763 		fatalx("bad path \"%s\": must be an absolute path", argv0);
1764 
1765 	if (geteuid() && (proc_id == PROC_GOTD || proc_id == PROC_LISTEN))
1766 		fatalx("need root privileges");
1767 
1768 	log_init(daemonize ? 0 : 1, LOG_DAEMON);
1769 	log_setverbose(verbosity);
1770 
1771 	if (parse_config(confpath, proc_id, &gotd) != 0)
1772 		return 1;
1773 
1774 	gotd.argv0 = argv0;
1775 	gotd.daemonize = daemonize;
1776 	gotd.verbosity = verbosity;
1777 	gotd.confpath = confpath;
1778 
1779 	if (proc_id == PROC_GOTD &&
1780 	    (gotd.nrepos == 0 || TAILQ_EMPTY(&gotd.repos)))
1781 		fatalx("no repository defined in configuration file");
1782 
1783 	pw = getpwnam(gotd.user_name);
1784 	if (pw == NULL)
1785 		fatalx("user %s not found", gotd.user_name);
1786 
1787 	if (pw->pw_uid == 0) {
1788 		fatalx("cannot run %s as %s: the user running %s "
1789 		    "must not be the superuser",
1790 		    getprogname(), pw->pw_name, getprogname());
1791 	}
1792 
1793 	if (proc_id == PROC_LISTEN &&
1794 	    !got_path_is_absolute(gotd.unix_socket_path))
1795 		fatalx("bad unix socket path \"%s\": must be an absolute path",
1796 		    gotd.unix_socket_path);
1797 
1798 	if (noaction)
1799 		return 0;
1800 
1801 	if (proc_id == PROC_GOTD) {
1802 		gotd.pid = getpid();
1803 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1804 		start_listener(argv0, confpath, daemonize, verbosity);
1805 		arc4random_buf(&clients_hash_key, sizeof(clients_hash_key));
1806 		if (daemonize && daemon(1, 0) == -1)
1807 			fatal("daemon");
1808 	} else if (proc_id == PROC_LISTEN) {
1809 		snprintf(title, sizeof(title), "%s", gotd_proc_names[proc_id]);
1810 		if (verbosity) {
1811 			log_info("socket: %s", gotd.unix_socket_path);
1812 			log_info("user: %s", pw->pw_name);
1813 		}
1814 
1815 		fd = unix_socket_listen(gotd.unix_socket_path, pw->pw_uid,
1816 		    pw->pw_gid);
1817 		if (fd == -1) {
1818 			fatal("cannot listen on unix socket %s",
1819 			    gotd.unix_socket_path);
1820 		}
1821 		if (daemonize && daemon(0, 0) == -1)
1822 			fatal("daemon");
1823 	} else if (proc_id == PROC_AUTH) {
1824 		snprintf(title, sizeof(title), "%s %s",
1825 		    gotd_proc_names[proc_id], repo_path);
1826 		if (daemonize && daemon(0, 0) == -1)
1827 			fatal("daemon");
1828 	} else if (proc_id == PROC_REPO_READ || proc_id == PROC_REPO_WRITE ||
1829 	    proc_id == PROC_SESSION) {
1830 		error = got_repo_pack_fds_open(&pack_fds);
1831 		if (error != NULL)
1832 			fatalx("cannot open pack tempfiles: %s", error->msg);
1833 		error = got_repo_temp_fds_open(&temp_fds);
1834 		if (error != NULL)
1835 			fatalx("cannot open pack tempfiles: %s", error->msg);
1836 		if (repo_path == NULL)
1837 			fatalx("repository path not specified");
1838 		snprintf(title, sizeof(title), "%s %s",
1839 		    gotd_proc_names[proc_id], repo_path);
1840 		if (daemonize && daemon(0, 0) == -1)
1841 			fatal("daemon");
1842 	} else
1843 		fatal("invalid process id %d", proc_id);
1844 
1845 	setproctitle("%s", title);
1846 	log_procinit(title);
1847 
1848 	/* Drop root privileges. */
1849 	if (setgid(pw->pw_gid) == -1)
1850 		fatal("setgid %d failed", pw->pw_gid);
1851 	if (setuid(pw->pw_uid) == -1)
1852 		fatal("setuid %d failed", pw->pw_uid);
1853 
1854 	event_init();
1855 
1856 	switch (proc_id) {
1857 	case PROC_GOTD:
1858 #ifndef PROFILE
1859 		/* "exec" promise will be limited to argv[0] via unveil(2). */
1860 		if (pledge("stdio proc exec sendfd recvfd unveil", NULL) == -1)
1861 			err(1, "pledge");
1862 #endif
1863 		break;
1864 	case PROC_LISTEN:
1865 #ifndef PROFILE
1866 		if (pledge("stdio sendfd unix unveil", NULL) == -1)
1867 			err(1, "pledge");
1868 #endif
1869 		/*
1870 		 * Ensure that AF_UNIX bind(2) cannot be used with any other
1871 		 * sockets by revoking all filesystem access via unveil(2).
1872 		 */
1873 		apply_unveil_none();
1874 
1875 		listen_main(title, fd, gotd.connection_limits,
1876 		    gotd.nconnection_limits);
1877 		/* NOTREACHED */
1878 		break;
1879 	case PROC_AUTH:
1880 #ifndef PROFILE
1881 		if (pledge("stdio getpw recvfd unix unveil", NULL) == -1)
1882 			err(1, "pledge");
1883 #endif
1884 		/*
1885 		 * We need the "unix" pledge promise for getpeername(2) only.
1886 		 * Ensure that AF_UNIX bind(2) cannot be used by revoking all
1887 		 * filesystem access via unveil(2). Access to password database
1888 		 * files will still work since "getpw" bypasses unveil(2).
1889 		 */
1890 		apply_unveil_none();
1891 
1892 		auth_main(title, &gotd.repos, repo_path);
1893 		/* NOTREACHED */
1894 		break;
1895 	case PROC_SESSION:
1896 #ifndef PROFILE
1897 		/*
1898 		 * The "recvfd" promise is only needed during setup and
1899 		 * will be removed in a later pledge(2) call.
1900 		 */
1901 		if (pledge("stdio rpath wpath cpath recvfd sendfd fattr flock "
1902 		    "unveil", NULL) == -1)
1903 			err(1, "pledge");
1904 #endif
1905 		apply_unveil_repo_readwrite(repo_path);
1906 		session_main(title, repo_path, pack_fds, temp_fds,
1907 		    &gotd.request_timeout);
1908 		/* NOTREACHED */
1909 		break;
1910 	case PROC_REPO_READ:
1911 #ifndef PROFILE
1912 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1913 			err(1, "pledge");
1914 #endif
1915 		apply_unveil_repo_readonly(repo_path);
1916 		repo_read_main(title, repo_path, pack_fds, temp_fds);
1917 		/* NOTREACHED */
1918 		exit(0);
1919 	case PROC_REPO_WRITE:
1920 #ifndef PROFILE
1921 		if (pledge("stdio rpath recvfd unveil", NULL) == -1)
1922 			err(1, "pledge");
1923 #endif
1924 		apply_unveil_repo_readonly(repo_path);
1925 		repo_write_main(title, repo_path, pack_fds, temp_fds);
1926 		/* NOTREACHED */
1927 		exit(0);
1928 	default:
1929 		fatal("invalid process id %d", proc_id);
1930 	}
1931 
1932 	if (proc_id != PROC_GOTD)
1933 		fatal("invalid process id %d", proc_id);
1934 
1935 	apply_unveil_selfexec();
1936 
1937 	signal_set(&evsigint, SIGINT, gotd_sighdlr, NULL);
1938 	signal_set(&evsigterm, SIGTERM, gotd_sighdlr, NULL);
1939 	signal_set(&evsighup, SIGHUP, gotd_sighdlr, NULL);
1940 	signal_set(&evsigusr1, SIGUSR1, gotd_sighdlr, NULL);
1941 	signal(SIGPIPE, SIG_IGN);
1942 
1943 	signal_add(&evsigint, NULL);
1944 	signal_add(&evsigterm, NULL);
1945 	signal_add(&evsighup, NULL);
1946 	signal_add(&evsigusr1, NULL);
1947 
1948 	gotd_imsg_event_add(&gotd.listen_proc.iev);
1949 
1950 	event_dispatch();
1951 
1952 	free(repo_path);
1953 	gotd_shutdown();
1954 
1955 	return 0;
1956 }