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 
55 #include "proc.h"
56 #include "gotwebd.h"
57 
58 #define SOCKS_BACKLOG 5
59 #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
60 
61 
62 volatile int client_cnt;
63 
64 struct timeval	timeout = { TIMEOUT_DEFAULT, 0 };
65 
66 void	 sockets_sighdlr(int, short, void *);
67 void	 sockets_run(struct privsep *, struct privsep_proc *, void *);
68 void	 sockets_launch(void);
69 void	 sockets_purge(struct gotwebd *);
70 void	 sockets_accept_paused(int, short, void *);
71 void	 sockets_rlimit(int);
72 
73 
74 int	 sockets_dispatch_gotwebd(int, struct privsep_proc *, struct imsg *);
75 int	 sockets_unix_socket_listen(struct privsep *, struct socket *);
76 int	 sockets_create_socket(struct addresslist *, in_port_t);
77 int	 sockets_accept_reserve(int, struct sockaddr *, socklen_t *, int,
78 	    volatile int *);
79 
80 struct socket *sockets_conf_new_socket(struct gotwebd *, struct server *,
81     int, int);
82 
83 int cgi_inflight = 0;
84 
85 static struct privsep_proc procs[] = {
86 	{ "gotwebd",	PROC_GOTWEBD,	sockets_dispatch_gotwebd  },
87 };
88 
89 void
90 sockets(struct privsep *ps, struct privsep_proc *p)
91 {
92 	proc_run(ps, p, procs, nitems(procs), sockets_run, NULL);
93 }
94 
95 void
96 sockets_run(struct privsep *ps, struct privsep_proc *p, void *arg)
97 {
98 	if (config_init(ps->ps_env) == -1)
99 		fatal("failed to initialize configuration");
100 
101 	p->p_shutdown = sockets_shutdown;
102 
103 	sockets_rlimit(-1);
104 
105 	signal_del(&ps->ps_evsigchld);
106 	signal_set(&ps->ps_evsigchld, SIGCHLD, sockets_sighdlr, ps);
107 	signal_add(&ps->ps_evsigchld, NULL);
108 
109 #ifndef PROFILE
110 	if (pledge("stdio rpath wpath cpath inet recvfd proc exec sendfd",
111 	    NULL) == -1)
112 		fatal("pledge");
113 #endif
114 }
115 
116 void
117 sockets_parse_sockets(struct gotwebd *env)
118 {
119 	struct server *srv;
120 	struct socket *new_sock = NULL;
121 	int sock_id = 0, ipv4 = 0, ipv6 = 0;
122 
123 	TAILQ_FOREACH(srv, &env->servers, entry) {
124 		if (srv->unix_socket) {
125 			sock_id++;
126 			new_sock = sockets_conf_new_socket(env, srv,
127 			    sock_id, AF_UNIX);
128 			/* Should always succeed. */
129 			TAILQ_INSERT_TAIL(&env->sockets, new_sock, entry);
130 		}
131 
132 		if (srv->fcgi_socket) {
133 			sock_id++;
134 			new_sock = sockets_conf_new_socket(env, srv, sock_id,
135 			    AF_INET);
136 			if (new_sock) {
137 				TAILQ_INSERT_TAIL(&env->sockets, new_sock,
138 				    entry);
139 				ipv4 = 1;
140 				sock_id++;
141 			}
142 
143 			new_sock = sockets_conf_new_socket(env, srv, sock_id,
144 			    AF_INET6);
145 			if (new_sock) {
146 				TAILQ_INSERT_TAIL(&env->sockets,
147 				    new_sock, entry);
148 				ipv6 = 1;
149 			}
150 
151 			if (ipv4 == 0 && ipv6 == 0) {
152 				fatalx("%s: have no IP addresses to listen "
153 				    "for FCGI connections", __func__);
154 			}
155 		}
156 	}
157 }
158 
159 /* Returns NULL if no addresses in the requested family are configured. */
160 struct socket *
161 sockets_conf_new_socket(struct gotwebd *env, struct server *srv, int id,
162     int af_type)
163 {
164 	struct socket *sock;
165 	struct address *a, *acp;
166 	int n;
167 
168 	if ((sock = calloc(1, sizeof(*sock))) == NULL)
169 		fatalx("%s: calloc", __func__);
170 
171 	TAILQ_INIT(&sock->conf.al);
172 
173 	sock->conf.id = id;
174 	sock->fd = -1;
175 	sock->conf.af_type = af_type;
176 
177 	if (af_type == AF_UNIX) {
178 		if (strlcpy(sock->conf.unix_socket_name,
179 		    srv->unix_socket_name,
180 		    sizeof(sock->conf.unix_socket_name)) >=
181 		    sizeof(sock->conf.unix_socket_name)) {
182 			free(sock);
183 			fatalx("%s: strlcpy", __func__);
184 		}
185 	}
186 
187 	sock->conf.fcgi_socket_port = srv->fcgi_socket_port;
188 
189 	n = snprintf(sock->conf.name, GOTWEBD_MAXTEXT, "%s_parent",
190 	    srv->name);
191 	if (n < 0 || (size_t)n >= GOTWEBD_MAXTEXT) {
192 		free(sock);
193 		fatalx("%s: snprintf", __func__);
194 	}
195 
196 	if (strlcpy(sock->conf.srv_name, srv->name,
197 	    sizeof(sock->conf.srv_name)) >= sizeof(sock->conf.srv_name)) {
198 		free(sock);
199 		fatalx("%s: strlcpy", __func__);
200 	}
201 
202 	TAILQ_FOREACH(a, &srv->al, entry) {
203 		if (a->ss.ss_family != af_type)
204 			continue;
205 
206 		if ((acp = calloc(1, sizeof(*acp))) == NULL) {
207 			free(sock);
208 			fatal("%s: calloc", __func__);
209 		}
210 		memcpy(&acp->ss, &a->ss, sizeof(acp->ss));
211 		acp->ipproto = a->ipproto;
212 		acp->prefixlen = a->prefixlen;
213 		acp->port = a->port;
214 		if (strlen(a->ifname) != 0) {
215 			if (strlcpy(acp->ifname, a->ifname,
216 			    sizeof(acp->ifname)) >= sizeof(acp->ifname)) {
217 				fatalx("%s: interface name truncated",
218 				    __func__);
219 			}
220 		}
221 
222 		TAILQ_INSERT_TAIL(&sock->conf.al, acp, entry);
223 	}
224 
225 	if ((af_type == AF_INET || af_type == AF_INET6) &&
226 	    TAILQ_EMPTY(&sock->conf.al)) {
227 		free(sock);
228 		return NULL;
229 	}
230 
231 	return (sock);
232 }
233 
234 void
235 sockets_launch(void)
236 {
237 	struct socket *sock;
238 
239 	TAILQ_FOREACH(sock, &gotwebd_env->sockets, entry) {
240 		log_debug("%s: configuring socket %d (%d)", __func__,
241 		    sock->conf.id, sock->fd);
242 
243 		event_set(&sock->ev, sock->fd, EV_READ | EV_PERSIST,
244 		    sockets_socket_accept, sock);
245 
246 		if (event_add(&sock->ev, NULL))
247 			fatalx("event add sock");
248 
249 		evtimer_set(&sock->pause, sockets_accept_paused, sock);
250 
251 		log_debug("%s: running socket listener %d", __func__,
252 		    sock->conf.id);
253 	}
254 }
255 
256 void
257 sockets_purge(struct gotwebd *env)
258 {
259 	struct socket *sock, *tsock;
260 
261 	/* shutdown and remove sockets */
262 	TAILQ_FOREACH_SAFE(sock, &env->sockets, entry, tsock) {
263 		if (event_initialized(&sock->ev))
264 			event_del(&sock->ev);
265 		if (evtimer_initialized(&sock->evt))
266 			evtimer_del(&sock->evt);
267 		if (evtimer_initialized(&sock->pause))
268 			evtimer_del(&sock->pause);
269 		if (sock->fd != -1)
270 			close(sock->fd);
271 		TAILQ_REMOVE(&env->sockets, sock, entry);
272 	}
273 }
274 
275 int
276 sockets_dispatch_gotwebd(int fd, struct privsep_proc *p, struct imsg *imsg)
277 {
278 	struct privsep *ps = p->p_ps;
279 	int res = 0, cmd = 0, verbose;
280 
281 	switch (imsg->hdr.type) {
282 	case IMSG_CFG_SRV:
283 		config_getserver(gotwebd_env, imsg);
284 		break;
285 	case IMSG_CFG_SOCK:
286 		config_getsock(gotwebd_env, imsg);
287 		break;
288 	case IMSG_CFG_FD:
289 		config_getfd(gotwebd_env, imsg);
290 		break;
291 	case IMSG_CFG_DONE:
292 		config_getcfg(gotwebd_env, imsg);
293 		break;
294 	case IMSG_CTL_START:
295 		sockets_launch();
296 		break;
297 	case IMSG_CTL_VERBOSE:
298 		IMSG_SIZE_CHECK(imsg, &verbose);
299 		memcpy(&verbose, imsg->data, sizeof(verbose));
300 		log_setverbose(verbose);
301 		break;
302 	default:
303 		return -1;
304 	}
305 
306 	switch (cmd) {
307 	case 0:
308 		break;
309 	default:
310 		if (proc_compose_imsg(ps, PROC_GOTWEBD, -1, cmd,
311 		    imsg->hdr.peerid, -1, &res, sizeof(res)) == -1)
312 			return -1;
313 		break;
314 	}
315 
316 	return 0;
317 }
318 
319 void
320 sockets_sighdlr(int sig, short event, void *arg)
321 {
322 	switch (sig) {
323 	case SIGHUP:
324 		log_info("%s: ignoring SIGHUP", __func__);
325 		break;
326 	case SIGPIPE:
327 		log_info("%s: ignoring SIGPIPE", __func__);
328 		break;
329 	case SIGUSR1:
330 		log_info("%s: ignoring SIGUSR1", __func__);
331 		break;
332 	case SIGCHLD:
333 		break;
334 	default:
335 		log_info("SIGNAL: %d", sig);
336 		fatalx("unexpected signal");
337 	}
338 }
339 
340 void
341 sockets_shutdown(void)
342 {
343 	struct server *srv, *tsrv;
344 	struct socket *sock, *tsock;
345 
346 	sockets_purge(gotwebd_env);
347 
348 	/* clean sockets */
349 	TAILQ_FOREACH_SAFE(sock, &gotwebd_env->sockets, entry, tsock) {
350 		TAILQ_REMOVE(&gotwebd_env->sockets, sock, entry);
351 		close(sock->fd);
352 		free(sock);
353 	}
354 
355 	/* clean servers */
356 	TAILQ_FOREACH_SAFE(srv, &gotwebd_env->servers, entry, tsrv)
357 		free(srv);
358 
359 	free(gotwebd_env);
360 }
361 
362 int
363 sockets_privinit(struct gotwebd *env, struct socket *sock)
364 {
365 	struct privsep *ps = env->gotwebd_ps;
366 
367 	if (sock->conf.af_type == AF_UNIX) {
368 		log_debug("%s: initializing unix socket %s", __func__,
369 		    sock->conf.unix_socket_name);
370 		sock->fd = sockets_unix_socket_listen(ps, sock);
371 		if (sock->fd == -1) {
372 			log_warnx("%s: create unix socket failed", __func__);
373 			return -1;
374 		}
375 	}
376 
377 	if (sock->conf.af_type == AF_INET || sock->conf.af_type == AF_INET6) {
378 		log_debug("%s: initializing %s FCGI socket on port %d for %s",
379 		    __func__, sock->conf.af_type == AF_INET ? "inet" : "inet6",
380 		    sock->conf.fcgi_socket_port, sock->conf.name);
381 		sock->fd = sockets_create_socket(&sock->conf.al,
382 		    sock->conf.fcgi_socket_port);
383 		if (sock->fd == -1) {
384 			log_warnx("%s: create unix socket failed", __func__);
385 			return -1;
386 		}
387 	}
388 
389 	return 0;
390 }
391 
392 int
393 sockets_unix_socket_listen(struct privsep *ps, struct socket *sock)
394 {
395 	struct gotwebd *env = ps->ps_env;
396 	struct sockaddr_un sun;
397 	struct socket *tsock;
398 	int u_fd = -1;
399 	mode_t old_umask, mode;
400 
401 	TAILQ_FOREACH(tsock, &env->sockets, entry) {
402 		if (strcmp(tsock->conf.unix_socket_name,
403 		    sock->conf.unix_socket_name) == 0 &&
404 		    tsock->fd != -1)
405 			return (tsock->fd);
406 	}
407 
408 	u_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
409 	if (u_fd == -1) {
410 		log_warn("%s: socket", __func__);
411 		return -1;
412 	}
413 
414 	sun.sun_family = AF_UNIX;
415 	if (strlcpy(sun.sun_path, sock->conf.unix_socket_name,
416 	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
417 		log_warn("%s: %s name too long", __func__,
418 		    sock->conf.unix_socket_name);
419 		close(u_fd);
420 		return -1;
421 	}
422 
423 	if (unlink(sock->conf.unix_socket_name) == -1) {
424 		if (errno != ENOENT) {
425 			log_warn("%s: unlink %s", __func__,
426 			    sock->conf.unix_socket_name);
427 			close(u_fd);
428 			return -1;
429 		}
430 	}
431 
432 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
433 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP;
434 
435 	if (bind(u_fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
436 		log_warn("%s: bind: %s", __func__, sock->conf.unix_socket_name);
437 		close(u_fd);
438 		(void)umask(old_umask);
439 		return -1;
440 	}
441 
442 	(void)umask(old_umask);
443 
444 	if (chmod(sock->conf.unix_socket_name, mode) == -1) {
445 		log_warn("%s: chmod", __func__);
446 		close(u_fd);
447 		(void)unlink(sock->conf.unix_socket_name);
448 		return -1;
449 	}
450 
451 	if (chown(sock->conf.unix_socket_name, ps->ps_pw->pw_uid,
452 	    ps->ps_pw->pw_gid) == -1) {
453 		log_warn("%s: chown", __func__);
454 		close(u_fd);
455 		(void)unlink(sock->conf.unix_socket_name);
456 		return -1;
457 	}
458 
459 	if (listen(u_fd, SOCKS_BACKLOG) == -1) {
460 		log_warn("%s: listen", __func__);
461 		return -1;
462 	}
463 
464 	return u_fd;
465 }
466 
467 int
468 sockets_create_socket(struct addresslist *al, in_port_t port)
469 {
470 	struct addrinfo hints;
471 	struct address *a;
472 	int fd = -1, o_val = 1, flags;
473 
474 	memset(&hints, 0, sizeof(hints));
475 	hints.ai_family = AF_UNSPEC;
476 	hints.ai_socktype = SOCK_STREAM;
477 	hints.ai_flags |= AI_PASSIVE;
478 
479 	TAILQ_FOREACH(a, al, entry) {
480 		switch (a->ss.ss_family) {
481 		case AF_INET:
482 			((struct sockaddr_in *)(&a->ss))->sin_port = port;
483 			break;
484 		case AF_INET6:
485 			((struct sockaddr_in6 *)(&a->ss))->sin6_port = port;
486 			break;
487 		default:
488 			log_warnx("%s: unknown address family", __func__);
489 			goto fail;
490 		}
491 
492 		fd = socket(a->ss.ss_family, hints.ai_socktype,
493 		    a->ipproto);
494 			log_debug("%s: opening socket (%d) for %s", __func__,
495 			    fd, a->ifname);
496 
497 		if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &o_val,
498 		    sizeof(int)) == -1) {
499 			log_warn("%s: setsockopt error", __func__);
500 			return -1;
501 		}
502 
503 		/* non-blocking */
504 		flags = fcntl(fd, F_GETFL);
505 		flags |= O_NONBLOCK;
506 		fcntl(fd, F_SETFL, flags);
507 
508 		if (bind(fd, (struct sockaddr *)&a->ss, a->ss.ss_len) == -1) {
509 			close(fd);
510 			log_info("%s: can't bind to port %d", __func__,
511 			    ntohs(port));
512 			goto fail;
513 		}
514 
515 		if (listen(fd, SOMAXCONN) == -1) {
516 			log_warn("%s, unable to listen on socket", __func__);
517 			goto fail;
518 		}
519 	}
520 
521 	free(a);
522 	return (fd);
523 fail:
524 	free(a);
525 	return -1;
526 }
527 
528 int
529 sockets_accept_reserve(int sockfd, struct sockaddr *addr, socklen_t *addrlen,
530     int reserve, volatile int *counter)
531 {
532 	int ret;
533 
534 	if (getdtablecount() + reserve +
535 	    ((*counter + 1) * FD_NEEDED) >= getdtablesize()) {
536 		log_debug("inflight fds exceeded");
537 		errno = EMFILE;
538 		return -1;
539 	}
540 
541 	if ((ret = accept4(sockfd, addr, addrlen,
542 	    SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
543 		(*counter)++;
544 		log_debug("inflight incremented, now %d", *counter);
545 	}
546 
547 	return ret;
548 }
549 
550 void
551 sockets_accept_paused(int fd, short events, void *arg)
552 {
553 	struct socket *sock = (struct socket *)arg;
554 
555 	event_add(&sock->ev, NULL);
556 }
557 
558 void
559 sockets_socket_accept(int fd, short event, void *arg)
560 {
561 	struct socket *sock = (struct socket *)arg;
562 	struct sockaddr_storage ss;
563 	struct timeval backoff;
564 	struct request *c = NULL;
565 	socklen_t len;
566 	int s;
567 
568 	backoff.tv_sec = 1;
569 	backoff.tv_usec = 0;
570 
571 	event_add(&sock->ev, NULL);
572 	if (event & EV_TIMEOUT)
573 		return;
574 
575 	len = sizeof(ss);
576 
577 	s = sockets_accept_reserve(fd, (struct sockaddr *)&ss, &len,
578 	    FD_RESERVE, &cgi_inflight);
579 
580 	if (s == -1) {
581 		switch (errno) {
582 		case EINTR:
583 		case EWOULDBLOCK:
584 		case ECONNABORTED:
585 			return;
586 		case EMFILE:
587 		case ENFILE:
588 			event_del(&sock->ev);
589 			evtimer_add(&sock->pause, &backoff);
590 			return;
591 		default:
592 			log_warn("%s: accept", __func__);
593 		}
594 	}
595 
596 	if (client_cnt > GOTWEBD_MAXCLIENTS)
597 		goto err;
598 
599 	c = calloc(1, sizeof(struct request));
600 	if (c == NULL) {
601 		log_warn("%s", __func__);
602 		close(s);
603 		cgi_inflight--;
604 		return;
605 	}
606 
607 	c->fd = s;
608 	c->sock = sock;
609 	memcpy(c->priv_fd, sock->priv_fd, sizeof(c->priv_fd));
610 	c->buf_pos = 0;
611 	c->buf_len = 0;
612 	c->request_started = 0;
613 	c->sock->client_status = CLIENT_CONNECT;
614 
615 	event_set(&c->ev, s, EV_READ, fcgi_request, c);
616 	event_add(&c->ev, NULL);
617 
618 	evtimer_set(&c->tmo, fcgi_timeout, c);
619 	evtimer_add(&c->tmo, &timeout);
620 
621 	client_cnt++;
622 
623 	return;
624 err:
625 	cgi_inflight--;
626 	close(s);
627 	if (c != NULL)
628 		free(c);
629 }
630 
631 void
632 sockets_rlimit(int maxfd)
633 {
634 	struct rlimit rl;
635 
636 	if (getrlimit(RLIMIT_NOFILE, &rl) == -1)
637 		fatal("%s: failed to get resource limit", __func__);
638 	log_debug("%s: max open files %llu", __func__,
639 	    (unsigned long long)rl.rlim_max);
640 
641 	/*
642 	 * Allow the maximum number of open file descriptors for this
643 	 * login class (which should be the class "daemon" by default).
644 	 */
645 	if (maxfd == -1)
646 		rl.rlim_cur = rl.rlim_max;
647 	else
648 		rl.rlim_cur = MAXIMUM(rl.rlim_max, (rlim_t)maxfd);
649 	if (setrlimit(RLIMIT_NOFILE, &rl) == -1)
650 		fatal("%s: failed to set resource limit", __func__);
651 }