1 /*
2  * Copyright (c) 2016, 2019, 2020-2021 Tracey Emery <tracey@traceyemery.net>
3  * Copyright (c) 2015 Mike Larkin <mlarkin@openbsd.org>
4  * Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
5  * Copyright (c) 2013 Florian Obser <florian@openbsd.org>
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #include <sys/param.h>
21 #include <sys/ioctl.h>
22 #include <sys/queue.h>
23 #include <sys/wait.h>
24 #include <sys/uio.h>
25 #include <sys/resource.h>
26 #include <sys/socket.h>
27 #include <sys/stat.h>
28 #include <sys/time.h>
29 #include <sys/types.h>
30 #include <sys/mman.h>
31 #include <sys/un.h>
32 
33 #include <net/if.h>
34 #include <netinet/in.h>
35 
36 #include <errno.h>
37 #include <event.h>
38 #include <fcntl.h>
39 #include <ifaddrs.h>
40 #include <imsg.h>
41 #include <limits.h>
42 #include <netdb.h>
43 #include <poll.h>
44 #include <pwd.h>
45 #include <stddef.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <unistd.h>
50 #include <util.h>
51 
52 #include "got_error.h"
53 #include "got_opentemp.h"
54 #include "got_reference.h"
55 #include "got_repository.h"
56 #include "got_privsep.h"
57 
58 #include "gotwebd.h"
59 #include "tmpl.h"
60 
61 #define SOCKS_BACKLOG 5
62 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
63 
64 volatile int client_cnt;
65 
66 static struct timeval	timeout = { TIMEOUT_DEFAULT, 0 };
67 
68 static void	 sockets_sighdlr(int, short, void *);
69 static void	 sockets_shutdown(void);
70 static void	 sockets_launch(void);
71 static void	 sockets_purge(struct gotwebd *);
72 static void	 sockets_accept_paused(int, short, void *);
73 static void	 sockets_rlimit(int);
74 
75 static void	 sockets_dispatch_main(int, short, void *);
76 static int	 sockets_unix_socket_listen(struct gotwebd *, struct socket *);
77 static int	 sockets_create_socket(struct address *);
78 static int	 sockets_accept_reserve(int, struct sockaddr *, socklen_t *,
79 		    int, volatile int *);
80 
81 static struct socket *sockets_conf_new_socket_unix(struct gotwebd *,
82 		    struct server *, int);
83 static struct socket *sockets_conf_new_socket_fcgi(struct gotwebd *,
84 		    struct server *, int, struct address *);
85 
86 int cgi_inflight = 0;
87 
88 void
89 sockets(struct gotwebd *env, int fd)
90 {
91 	struct event	 sighup, sigusr1, sigchld;
92 
93 	event_init();
94 
95 	sockets_rlimit(-1);
96 
97 	if (config_init(env) == -1)
98 		fatal("failed to initialize configuration");
99 
100 	if ((env->iev_parent = malloc(sizeof(*env->iev_parent))) == NULL)
101 		fatal("malloc");
102 	imsg_init(&env->iev_parent->ibuf, fd);
103 	env->iev_parent->handler = sockets_dispatch_main;
104 	env->iev_parent->data = env->iev_parent;
105 	event_set(&env->iev_parent->ev, fd, EV_READ, sockets_dispatch_main,
106 	    env->iev_parent);
107 	event_add(&env->iev_parent->ev, NULL);
108 
109 	signal(SIGPIPE, SIG_IGN);
110 
111 	signal_set(&sighup, SIGHUP, sockets_sighdlr, env);
112 	signal_add(&sighup, NULL);
113 	signal_set(&sigusr1, SIGUSR1, sockets_sighdlr, env);
114 	signal_add(&sigusr1, NULL);
115 	signal_set(&sigchld, SIGCHLD, sockets_sighdlr, env);
116 	signal_add(&sigchld, NULL);
117 
118 #ifndef PROFILE
119 	if (pledge("stdio rpath inet recvfd proc exec sendfd unveil",
120 	    NULL) == -1)
121 		fatal("pledge");
122 #endif
123 
124 	event_dispatch();
125 	sockets_shutdown();
126 }
127 
128 void
129 sockets_parse_sockets(struct gotwebd *env)
130 {
131 	struct server *srv;
132 	struct address *a;
133 	struct socket *new_sock = NULL;
134 	int sock_id = 1;
135 
136 	TAILQ_FOREACH(srv, &env->servers, entry) {
137 		if (srv->unix_socket) {
138 			new_sock = sockets_conf_new_socket_unix(env, srv,
139 			    sock_id);
140 			if (new_sock) {
141 				sock_id++;
142 				TAILQ_INSERT_TAIL(&env->sockets, new_sock,
143 				    entry);
144 			}
145 		}
146 
147 		if (srv->fcgi_socket) {
148 			if (TAILQ_EMPTY(&srv->al)) {
149 				fatalx("%s: server %s has no IP addresses to "
150 				    "listen for FCGI connections", __func__,
151 				    srv->name);
152 			}
153 			TAILQ_FOREACH(a, &srv->al, entry) {
154 				if (a->ss.ss_family != AF_INET &&
155 				    a->ss.ss_family != AF_INET6)
156 					continue;
157 				new_sock = sockets_conf_new_socket_fcgi(env,
158 				    srv, sock_id, a);
159 				if (new_sock) {
160 					sock_id++;
161 					TAILQ_INSERT_TAIL(&env->sockets,
162 					    new_sock, entry);
163 				}
164 			}
165 		}
166 	}
167 }
168 
169 static struct socket *
170 sockets_conf_new_socket_unix(struct gotwebd *env, struct server *srv, int id)
171 {
172 	struct socket *sock;
173 	int n;
174 
175 	if ((sock = calloc(1, sizeof(*sock))) == NULL)
176 		fatalx("%s: calloc", __func__);
177 
178 	sock->conf.id = id;
179 	sock->fd = -1;
180 	sock->conf.af_type = AF_UNIX;
181 
182 	if (strlcpy(sock->conf.unix_socket_name,
183 	    srv->unix_socket_name,
184 	    sizeof(sock->conf.unix_socket_name)) >=
185 	    sizeof(sock->conf.unix_socket_name)) {
186 		free(sock);
187 		fatalx("%s: strlcpy", __func__);
188 	}
189 
190 	n = snprintf(sock->conf.name, GOTWEBD_MAXTEXT, "%s_parent",
191 	    srv->name);
192 	if (n < 0 || (size_t)n >= GOTWEBD_MAXTEXT) {
193 		free(sock);
194 		fatalx("%s: snprintf", __func__);
195 	}
196 
197 	if (strlcpy(sock->conf.srv_name, srv->name,
198 	    sizeof(sock->conf.srv_name)) >= sizeof(sock->conf.srv_name)) {
199 		free(sock);
200 		fatalx("%s: strlcpy", __func__);
201 	}
202 
203 	return sock;
204 }
205 
206 static struct socket *
207 sockets_conf_new_socket_fcgi(struct gotwebd *env, struct server *srv, int id,
208     struct address *a)
209 {
210 	struct socket *sock;
211 	struct address *acp;
212 	int n;
213 
214 	if ((sock = calloc(1, sizeof(*sock))) == NULL)
215 		fatalx("%s: calloc", __func__);
216 
217 	sock->conf.id = id;
218 	sock->fd = -1;
219 	sock->conf.af_type = a->ss.ss_family;
220 
221 	sock->conf.fcgi_socket_port = a->port;
222 
223 	n = snprintf(sock->conf.name, GOTWEBD_MAXTEXT, "%s_parent",
224 	    srv->name);
225 	if (n < 0 || (size_t)n >= GOTWEBD_MAXTEXT) {
226 		free(sock);
227 		fatalx("%s: snprintf", __func__);
228 	}
229 
230 	if (strlcpy(sock->conf.srv_name, srv->name,
231 	    sizeof(sock->conf.srv_name)) >= sizeof(sock->conf.srv_name)) {
232 		free(sock);
233 		fatalx("%s: strlcpy", __func__);
234 	}
235 
236 	acp = &sock->conf.addr;
237 
238 	memcpy(&acp->ss, &a->ss, sizeof(acp->ss));
239 	acp->slen = a->slen;
240 	acp->ai_family = a->ai_family;
241 	acp->ai_socktype = a->ai_socktype;
242 	acp->ai_protocol = a->ai_protocol;
243 	acp->port = a->port;
244 	if (*a->ifname != '\0') {
245 		if (strlcpy(acp->ifname, a->ifname,
246 		    sizeof(acp->ifname)) >= sizeof(acp->ifname)) {
247 			fatalx("%s: interface name truncated",
248 			    __func__);
249 		}
250 	}
251 
252 	return (sock);
253 }
254 
255 static void
256 sockets_launch(void)
257 {
258 	struct socket *sock;
259 	struct server *srv;
260 	const struct got_error *error;
261 
262 	TAILQ_FOREACH(sock, &gotwebd_env->sockets, entry) {
263 		log_debug("%s: configuring socket %d (%d)", __func__,
264 		    sock->conf.id, sock->fd);
265 
266 		event_set(&sock->ev, sock->fd, EV_READ | EV_PERSIST,
267 		    sockets_socket_accept, sock);
268 
269 		if (event_add(&sock->ev, NULL))
270 			fatalx("event add sock");
271 
272 		evtimer_set(&sock->pause, sockets_accept_paused, sock);
273 
274 		log_debug("%s: running socket listener %d", __func__,
275 		    sock->conf.id);
276 	}
277 
278 	TAILQ_FOREACH(srv, &gotwebd_env->servers, entry) {
279 		if (unveil(srv->repos_path, "r") == -1)
280 			fatal("unveil %s", srv->repos_path);
281 	}
282 
283 	error = got_privsep_unveil_exec_helpers();
284 	if (error)
285 		fatal("%s", error->msg);
286 
287 	if (unveil(NULL, NULL) == -1)
288 		fatal("unveil");
289 }
290 
291 static void
292 sockets_purge(struct gotwebd *env)
293 {
294 	struct socket *sock, *tsock;
295 
296 	/* shutdown and remove sockets */
297 	TAILQ_FOREACH_SAFE(sock, &env->sockets, entry, tsock) {
298 		if (event_initialized(&sock->ev))
299 			event_del(&sock->ev);
300 		if (evtimer_initialized(&sock->evt))
301 			evtimer_del(&sock->evt);
302 		if (evtimer_initialized(&sock->pause))
303 			evtimer_del(&sock->pause);
304 		if (sock->fd != -1)
305 			close(sock->fd);
306 		TAILQ_REMOVE(&env->sockets, sock, entry);
307 	}
308 }
309 
310 static void
311 sockets_dispatch_main(int fd, short event, void *arg)
312 {
313 	struct imsgev		*iev = arg;
314 	struct imsgbuf		*ibuf;
315 	struct imsg		 imsg;
316 	struct gotwebd		*env = gotwebd_env;
317 	ssize_t			 n;
318 	int			 shut = 0;
319 
320 	ibuf = &iev->ibuf;
321 
322 	if (event & EV_READ) {
323 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
324 			fatal("imsg_read error");
325 		if (n == 0)	/* Connection closed */
326 			shut = 1;
327 	}
328 	if (event & EV_WRITE) {
329 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
330 			fatal("msgbuf_write");
331 		if (n == 0)	/* Connection closed */
332 			shut = 1;
333 	}
334 
335 	for (;;) {
336 		if ((n = imsg_get(ibuf, &imsg)) == -1)
337 			fatal("imsg_get");
338 		if (n == 0)	/* No more messages. */
339 			break;
340 
341 		switch (imsg.hdr.type) {
342 		case IMSG_CFG_SRV:
343 			config_getserver(env, &imsg);
344 			break;
345 		case IMSG_CFG_SOCK:
346 			config_getsock(env, &imsg);
347 			break;
348 		case IMSG_CFG_FD:
349 			config_getfd(env, &imsg);
350 			break;
351 		case IMSG_CFG_DONE:
352 			config_getcfg(env, &imsg);
353 			break;
354 		case IMSG_CTL_START:
355 			sockets_launch();
356 			break;
357 		default:
358 			fatalx("%s: unknown imsg type %d", __func__,
359 			    imsg.hdr.type);
360 		}
361 
362 		imsg_free(&imsg);
363 	}
364 
365 	if (!shut)
366 		imsg_event_add(iev);
367 	else {
368 		/* This pipe is dead.  Remove its event handler */
369 		event_del(&iev->ev);
370 		event_loopexit(NULL);
371 	}
372 }
373 
374 static void
375 sockets_sighdlr(int sig, short event, void *arg)
376 {
377 	switch (sig) {
378 	case SIGHUP:
379 		log_info("%s: ignoring SIGHUP", __func__);
380 		break;
381 	case SIGPIPE:
382 		log_info("%s: ignoring SIGPIPE", __func__);
383 		break;
384 	case SIGUSR1:
385 		log_info("%s: ignoring SIGUSR1", __func__);
386 		break;
387 	case SIGCHLD:
388 		break;
389 	default:
390 		log_info("SIGNAL: %d", sig);
391 		fatalx("unexpected signal");
392 	}
393 }
394 
395 static void
396 sockets_shutdown(void)
397 {
398 	struct server *srv, *tsrv;
399 	struct socket *sock, *tsock;
400 
401 	sockets_purge(gotwebd_env);
402 
403 	/* clean sockets */
404 	TAILQ_FOREACH_SAFE(sock, &gotwebd_env->sockets, entry, tsock) {
405 		TAILQ_REMOVE(&gotwebd_env->sockets, sock, entry);
406 		close(sock->fd);
407 		free(sock);
408 	}
409 
410 	/* clean servers */
411 	TAILQ_FOREACH_SAFE(srv, &gotwebd_env->servers, entry, tsrv)
412 		free(srv);
413 
414 	free(gotwebd_env);
415 }
416 
417 int
418 sockets_privinit(struct gotwebd *env, struct socket *sock)
419 {
420 	if (sock->conf.af_type == AF_UNIX) {
421 		log_debug("%s: initializing unix socket %s", __func__,
422 		    sock->conf.unix_socket_name);
423 		sock->fd = sockets_unix_socket_listen(env, sock);
424 		if (sock->fd == -1) {
425 			log_warnx("%s: create unix socket failed", __func__);
426 			return -1;
427 		}
428 	}
429 
430 	if (sock->conf.af_type == AF_INET || sock->conf.af_type == AF_INET6) {
431 		log_debug("%s: initializing %s FCGI socket on port %d for %s",
432 		    __func__, sock->conf.af_type == AF_INET ? "inet" : "inet6",
433 		    sock->conf.fcgi_socket_port, sock->conf.name);
434 		sock->fd = sockets_create_socket(&sock->conf.addr);
435 		if (sock->fd == -1) {
436 			log_warnx("%s: create FCGI socket failed", __func__);
437 			return -1;
438 		}
439 	}
440 
441 	return 0;
442 }
443 
444 static int
445 sockets_unix_socket_listen(struct gotwebd *env, struct socket *sock)
446 {
447 	struct sockaddr_un sun;
448 	struct socket *tsock;
449 	int u_fd = -1;
450 	mode_t old_umask, mode;
451 
452 	TAILQ_FOREACH(tsock, &env->sockets, entry) {
453 		if (strcmp(tsock->conf.unix_socket_name,
454 		    sock->conf.unix_socket_name) == 0 &&
455 		    tsock->fd != -1)
456 			return (tsock->fd);
457 	}
458 
459 	u_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
460 	if (u_fd == -1) {
461 		log_warn("%s: socket", __func__);
462 		return -1;
463 	}
464 
465 	sun.sun_family = AF_UNIX;
466 	if (strlcpy(sun.sun_path, sock->conf.unix_socket_name,
467 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
468 		log_warn("%s: %s name too long", __func__,
469 		    sock->conf.unix_socket_name);
470 		close(u_fd);
471 		return -1;
472 	}
473 
474 	if (unlink(sock->conf.unix_socket_name) == -1) {
475 		if (errno != ENOENT) {
476 			log_warn("%s: unlink %s", __func__,
477 			    sock->conf.unix_socket_name);
478 			close(u_fd);
479 			return -1;
480 		}
481 	}
482 
483 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
484 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP;
485 
486 	if (bind(u_fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
487 		log_warn("%s: bind: %s", __func__, sock->conf.unix_socket_name);
488 		close(u_fd);
489 		(void)umask(old_umask);
490 		return -1;
491 	}
492 
493 	(void)umask(old_umask);
494 
495 	if (chmod(sock->conf.unix_socket_name, mode) == -1) {
496 		log_warn("%s: chmod", __func__);
497 		close(u_fd);
498 		(void)unlink(sock->conf.unix_socket_name);
499 		return -1;
500 	}
501 
502 	if (chown(sock->conf.unix_socket_name, env->pw->pw_uid,
503 	    env->pw->pw_gid) == -1) {
504 		log_warn("%s: chown", __func__);
505 		close(u_fd);
506 		(void)unlink(sock->conf.unix_socket_name);
507 		return -1;
508 	}
509 
510 	if (listen(u_fd, SOCKS_BACKLOG) == -1) {
511 		log_warn("%s: listen", __func__);
512 		return -1;
513 	}
514 
515 	return u_fd;
516 }
517 
518 static int
519 sockets_create_socket(struct address *a)
520 {
521 	int fd = -1, o_val = 1, flags;
522 
523 	fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol);
524 	if (fd == -1)
525 		return -1;
526 
527 	log_debug("%s: opened socket (%d) for %s", __func__,
528 	    fd, a->ifname);
529 
530 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &o_val,
531 	    sizeof(int)) == -1) {
532 		log_warn("%s: setsockopt error", __func__);
533 		close(fd);
534 		return -1;
535 	}
536 
537 	/* non-blocking */
538 	flags = fcntl(fd, F_GETFL);
539 	flags |= O_NONBLOCK;
540 	if (fcntl(fd, F_SETFL, flags) == -1) {
541 		log_info("%s: could not enable non-blocking I/O", __func__);
542 		close(fd);
543 		return -1;
544 	}
545 
546 	if (bind(fd, (struct sockaddr *)&a->ss, a->slen) == -1) {
547 		close(fd);
548 		log_info("%s: can't bind to port %d", __func__, a->port);
549 		return -1;
550 	}
551 
552 	if (listen(fd, SOMAXCONN) == -1) {
553 		log_warn("%s, unable to listen on socket", __func__);
554 		close(fd);
555 		return -1;
556 	}
557 
558 	return (fd);
559 }
560 
561 static int
562 sockets_accept_reserve(int sockfd, struct sockaddr *addr, socklen_t *addrlen,
563     int reserve, volatile int *counter)
564 {
565 	int ret;
566 
567 	if (getdtablecount() + reserve +
568 	    ((*counter + 1) * FD_NEEDED) >= getdtablesize()) {
569 		log_debug("inflight fds exceeded");
570 		errno = EMFILE;
571 		return -1;
572 	}
573 
574 	if ((ret = accept4(sockfd, addr, addrlen,
575 	    SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
576 		(*counter)++;
577 		log_debug("inflight incremented, now %d", *counter);
578 	}
579 
580 	return ret;
581 }
582 
583 static void
584 sockets_accept_paused(int fd, short events, void *arg)
585 {
586 	struct socket *sock = (struct socket *)arg;
587 
588 	event_add(&sock->ev, NULL);
589 }
590 
591 void
592 sockets_socket_accept(int fd, short event, void *arg)
593 {
594 	struct socket *sock = (struct socket *)arg;
595 	struct sockaddr_storage ss;
596 	struct timeval backoff;
597 	struct request *c = NULL;
598 	socklen_t len;
599 	int s;
600 
601 	backoff.tv_sec = 1;
602 	backoff.tv_usec = 0;
603 
604 	event_add(&sock->ev, NULL);
605 	if (event & EV_TIMEOUT)
606 		return;
607 
608 	len = sizeof(ss);
609 
610 	s = sockets_accept_reserve(fd, (struct sockaddr *)&ss, &len,
611 	    FD_RESERVE, &cgi_inflight);
612 
613 	if (s == -1) {
614 		switch (errno) {
615 		case EINTR:
616 		case EWOULDBLOCK:
617 		case ECONNABORTED:
618 			return;
619 		case EMFILE:
620 		case ENFILE:
621 			event_del(&sock->ev);
622 			evtimer_add(&sock->pause, &backoff);
623 			return;
624 		default:
625 			log_warn("%s: accept", __func__);
626 		}
627 	}
628 
629 	if (client_cnt > GOTWEBD_MAXCLIENTS)
630 		goto err;
631 
632 	c = calloc(1, sizeof(struct request));
633 	if (c == NULL) {
634 		log_warn("%s", __func__);
635 		close(s);
636 		cgi_inflight--;
637 		return;
638 	}
639 
640 	c->tp = template(c, &fcgi_write, c->outbuf, sizeof(c->outbuf));
641 	if (c->tp == NULL) {
642 		log_warn("%s", __func__);
643 		close(s);
644 		cgi_inflight--;
645 		free(c);
646 		return;
647 	}
648 
649 	c->fd = s;
650 	c->sock = sock;
651 	memcpy(c->priv_fd, sock->priv_fd, sizeof(c->priv_fd));
652 	c->buf_pos = 0;
653 	c->buf_len = 0;
654 	c->request_started = 0;
655 	c->sock->client_status = CLIENT_CONNECT;
656 
657 	event_set(&c->ev, s, EV_READ|EV_PERSIST, fcgi_request, c);
658 	event_add(&c->ev, NULL);
659 
660 	evtimer_set(&c->tmo, fcgi_timeout, c);
661 	evtimer_add(&c->tmo, &timeout);
662 
663 	client_cnt++;
664 
665 	return;
666 err:
667 	cgi_inflight--;
668 	close(s);
669 	if (c != NULL)
670 		free(c);
671 }
672 
673 static void
674 sockets_rlimit(int maxfd)
675 {
676 	struct rlimit rl;
677 
678 	if (getrlimit(RLIMIT_NOFILE, &rl) == -1)
679 		fatal("%s: failed to get resource limit", __func__);
680 	log_debug("%s: max open files %llu", __func__,
681 	    (unsigned long long)rl.rlim_max);
682 
683 	/*
684 	 * Allow the maximum number of open file descriptors for this
685 	 * login class (which should be the class "daemon" by default).
686 	 */
687 	if (maxfd == -1)
688 		rl.rlim_cur = rl.rlim_max;
689 	else
690 		rl.rlim_cur = MAXIMUM(rl.rlim_max, (rlim_t)maxfd);
691 	if (setrlimit(RLIMIT_NOFILE, &rl) == -1)
692 		fatal("%s: failed to set resource limit", __func__);
693 }