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(struct gotwebd *,
82 		    int, struct address *);
83 
84 int cgi_inflight = 0;
85 
86 void
87 sockets(struct gotwebd *env, int fd)
88 {
89 	struct event	 sighup, sigint, sigusr1, sigchld, sigterm;
90 
91 	event_init();
92 
93 	sockets_rlimit(-1);
94 
95 	if (config_init(env) == -1)
96 		fatal("failed to initialize configuration");
97 
98 	if ((env->iev_parent = malloc(sizeof(*env->iev_parent))) == NULL)
99 		fatal("malloc");
100 	imsg_init(&env->iev_parent->ibuf, fd);
101 	env->iev_parent->handler = sockets_dispatch_main;
102 	env->iev_parent->data = env->iev_parent;
103 	event_set(&env->iev_parent->ev, fd, EV_READ, sockets_dispatch_main,
104 	    env->iev_parent);
105 	event_add(&env->iev_parent->ev, NULL);
106 
107 	signal(SIGPIPE, SIG_IGN);
108 
109 	signal_set(&sighup, SIGHUP, sockets_sighdlr, env);
110 	signal_add(&sighup, NULL);
111 	signal_set(&sigint, SIGINT, sockets_sighdlr, env);
112 	signal_add(&sigint, 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 	signal_set(&sigterm, SIGTERM, sockets_sighdlr, env);
118 	signal_add(&sigterm, NULL);
119 
120 #ifndef PROFILE
121 	if (pledge("stdio rpath inet recvfd proc exec sendfd unveil",
122 	    NULL) == -1)
123 		fatal("pledge");
124 #endif
125 
126 	event_dispatch();
127 	sockets_shutdown();
128 }
129 
130 void
131 sockets_parse_sockets(struct gotwebd *env)
132 {
133 	struct address *a;
134 	struct socket *new_sock = NULL;
135 	int sock_id = 1;
136 
137 	TAILQ_FOREACH(a, &env->addresses, entry) {
138 		new_sock = sockets_conf_new_socket(env, sock_id, a);
139 		if (new_sock) {
140 			sock_id++;
141 			TAILQ_INSERT_TAIL(&env->sockets,
142 			    new_sock, entry);
143 		}
144 	}
145 }
146 
147 static struct socket *
148 sockets_conf_new_socket(struct gotwebd *env, int id, struct address *a)
149 {
150 	struct socket *sock;
151 	struct address *acp;
152 
153 	if ((sock = calloc(1, sizeof(*sock))) == NULL)
154 		fatalx("%s: calloc", __func__);
155 
156 	sock->conf.id = id;
157 	sock->fd = -1;
158 	sock->conf.af_type = a->ss.ss_family;
159 
160 	if (a->ss.ss_family == AF_UNIX) {
161 		struct sockaddr_un *sun;
162 
163 		sun = (struct sockaddr_un *)&a->ss;
164 		if (strlcpy(sock->conf.unix_socket_name, sun->sun_path,
165 		    sizeof(sock->conf.unix_socket_name)) >=
166 		    sizeof(sock->conf.unix_socket_name))
167 			fatalx("unix socket path too long: %s", sun->sun_path);
168 	}
169 
170 	sock->conf.fcgi_socket_port = a->port;
171 
172 	acp = &sock->conf.addr;
173 
174 	memcpy(&acp->ss, &a->ss, sizeof(acp->ss));
175 	acp->slen = a->slen;
176 	acp->ai_family = a->ai_family;
177 	acp->ai_socktype = a->ai_socktype;
178 	acp->ai_protocol = a->ai_protocol;
179 	acp->port = a->port;
180 	if (*a->ifname != '\0') {
181 		if (strlcpy(acp->ifname, a->ifname,
182 		    sizeof(acp->ifname)) >= sizeof(acp->ifname)) {
183 			fatalx("%s: interface name truncated",
184 			    __func__);
185 		}
186 	}
187 
188 	return (sock);
189 }
190 
191 static void
192 sockets_launch(void)
193 {
194 	struct socket *sock;
195 	struct server *srv;
196 	const struct got_error *error;
197 
198 	TAILQ_FOREACH(sock, &gotwebd_env->sockets, entry) {
199 		log_debug("%s: configuring socket %d (%d)", __func__,
200 		    sock->conf.id, sock->fd);
201 
202 		event_set(&sock->ev, sock->fd, EV_READ | EV_PERSIST,
203 		    sockets_socket_accept, sock);
204 
205 		if (event_add(&sock->ev, NULL))
206 			fatalx("event add sock");
207 
208 		evtimer_set(&sock->pause, sockets_accept_paused, sock);
209 
210 		log_debug("%s: running socket listener %d", __func__,
211 		    sock->conf.id);
212 	}
213 
214 	TAILQ_FOREACH(srv, &gotwebd_env->servers, entry) {
215 		if (unveil(srv->repos_path, "r") == -1)
216 			fatal("unveil %s", srv->repos_path);
217 	}
218 
219 	error = got_privsep_unveil_exec_helpers();
220 	if (error)
221 		fatal("%s", error->msg);
222 
223 	if (unveil(NULL, NULL) == -1)
224 		fatal("unveil");
225 }
226 
227 static void
228 sockets_purge(struct gotwebd *env)
229 {
230 	struct socket *sock, *tsock;
231 
232 	/* shutdown and remove sockets */
233 	TAILQ_FOREACH_SAFE(sock, &env->sockets, entry, tsock) {
234 		if (event_initialized(&sock->ev))
235 			event_del(&sock->ev);
236 		if (evtimer_initialized(&sock->evt))
237 			evtimer_del(&sock->evt);
238 		if (evtimer_initialized(&sock->pause))
239 			evtimer_del(&sock->pause);
240 		if (sock->fd != -1)
241 			close(sock->fd);
242 		TAILQ_REMOVE(&env->sockets, sock, entry);
243 	}
244 }
245 
246 static void
247 sockets_dispatch_main(int fd, short event, void *arg)
248 {
249 	struct imsgev		*iev = arg;
250 	struct imsgbuf		*ibuf;
251 	struct imsg		 imsg;
252 	struct gotwebd		*env = gotwebd_env;
253 	ssize_t			 n;
254 	int			 shut = 0;
255 
256 	ibuf = &iev->ibuf;
257 
258 	if (event & EV_READ) {
259 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
260 			fatal("imsg_read error");
261 		if (n == 0)	/* Connection closed */
262 			shut = 1;
263 	}
264 	if (event & EV_WRITE) {
265 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
266 			fatal("msgbuf_write");
267 		if (n == 0)	/* Connection closed */
268 			shut = 1;
269 	}
270 
271 	for (;;) {
272 		if ((n = imsg_get(ibuf, &imsg)) == -1)
273 			fatal("imsg_get");
274 		if (n == 0)	/* No more messages. */
275 			break;
276 
277 		switch (imsg.hdr.type) {
278 		case IMSG_CFG_SRV:
279 			config_getserver(env, &imsg);
280 			break;
281 		case IMSG_CFG_SOCK:
282 			config_getsock(env, &imsg);
283 			break;
284 		case IMSG_CFG_FD:
285 			config_getfd(env, &imsg);
286 			break;
287 		case IMSG_CFG_DONE:
288 			config_getcfg(env, &imsg);
289 			break;
290 		case IMSG_CTL_START:
291 			sockets_launch();
292 			break;
293 		default:
294 			fatalx("%s: unknown imsg type %d", __func__,
295 			    imsg.hdr.type);
296 		}
297 
298 		imsg_free(&imsg);
299 	}
300 
301 	if (!shut)
302 		imsg_event_add(iev);
303 	else {
304 		/* This pipe is dead.  Remove its event handler */
305 		event_del(&iev->ev);
306 		event_loopexit(NULL);
307 	}
308 }
309 
310 static void
311 sockets_sighdlr(int sig, short event, void *arg)
312 {
313 	switch (sig) {
314 	case SIGHUP:
315 		log_info("%s: ignoring SIGHUP", __func__);
316 		break;
317 	case SIGPIPE:
318 		log_info("%s: ignoring SIGPIPE", __func__);
319 		break;
320 	case SIGUSR1:
321 		log_info("%s: ignoring SIGUSR1", __func__);
322 		break;
323 	case SIGCHLD:
324 		break;
325 	case SIGINT:
326 	case SIGTERM:
327 		sockets_shutdown();
328 		break;
329 	default:
330 		log_info("SIGNAL: %d", sig);
331 		fatalx("unexpected signal");
332 	}
333 }
334 
335 static void
336 sockets_shutdown(void)
337 {
338 	struct server *srv, *tsrv;
339 	struct socket *sock, *tsock;
340 
341 	sockets_purge(gotwebd_env);
342 
343 	/* clean sockets */
344 	TAILQ_FOREACH_SAFE(sock, &gotwebd_env->sockets, entry, tsock) {
345 		TAILQ_REMOVE(&gotwebd_env->sockets, sock, entry);
346 		close(sock->fd);
347 		free(sock);
348 	}
349 
350 	/* clean servers */
351 	TAILQ_FOREACH_SAFE(srv, &gotwebd_env->servers, entry, tsrv)
352 		free(srv);
353 
354 	free(gotwebd_env);
355 
356 	exit(0);
357 }
358 
359 int
360 sockets_privinit(struct gotwebd *env, struct socket *sock)
361 {
362 	if (sock->conf.af_type == AF_UNIX) {
363 		log_debug("%s: initializing unix socket %s", __func__,
364 		    sock->conf.unix_socket_name);
365 		sock->fd = sockets_unix_socket_listen(env, sock);
366 		if (sock->fd == -1) {
367 			log_warnx("%s: create unix socket failed", __func__);
368 			return -1;
369 		}
370 	}
371 
372 	if (sock->conf.af_type == AF_INET || sock->conf.af_type == AF_INET6) {
373 		log_debug("%s: initializing %s FCGI socket on port %d",
374 		    __func__, sock->conf.af_type == AF_INET ? "inet" : "inet6",
375 		    sock->conf.fcgi_socket_port);
376 		sock->fd = sockets_create_socket(&sock->conf.addr);
377 		if (sock->fd == -1) {
378 			log_warnx("%s: create FCGI socket failed", __func__);
379 			return -1;
380 		}
381 	}
382 
383 	return 0;
384 }
385 
386 static int
387 sockets_unix_socket_listen(struct gotwebd *env, struct socket *sock)
388 {
389 	int u_fd = -1;
390 	mode_t old_umask, mode;
391 
392 	u_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK| SOCK_CLOEXEC, 0);
393 	if (u_fd == -1) {
394 		log_warn("%s: socket", __func__);
395 		return -1;
396 	}
397 
398 	if (unlink(sock->conf.unix_socket_name) == -1) {
399 		if (errno != ENOENT) {
400 			log_warn("%s: unlink %s", __func__,
401 			    sock->conf.unix_socket_name);
402 			close(u_fd);
403 			return -1;
404 		}
405 	}
406 
407 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
408 	mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP;
409 
410 	if (bind(u_fd, (struct sockaddr *)&sock->conf.addr.ss,
411 	    sock->conf.addr.slen) == -1) {
412 		log_warn("%s: bind: %s", __func__, sock->conf.unix_socket_name);
413 		close(u_fd);
414 		(void)umask(old_umask);
415 		return -1;
416 	}
417 
418 	(void)umask(old_umask);
419 
420 	if (chmod(sock->conf.unix_socket_name, mode) == -1) {
421 		log_warn("%s: chmod", __func__);
422 		close(u_fd);
423 		(void)unlink(sock->conf.unix_socket_name);
424 		return -1;
425 	}
426 
427 	if (chown(sock->conf.unix_socket_name, env->pw->pw_uid,
428 	    env->pw->pw_gid) == -1) {
429 		log_warn("%s: chown", __func__);
430 		close(u_fd);
431 		(void)unlink(sock->conf.unix_socket_name);
432 		return -1;
433 	}
434 
435 	if (listen(u_fd, SOCKS_BACKLOG) == -1) {
436 		log_warn("%s: listen", __func__);
437 		return -1;
438 	}
439 
440 	return u_fd;
441 }
442 
443 static int
444 sockets_create_socket(struct address *a)
445 {
446 	int fd = -1, o_val = 1, flags;
447 
448 	fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol);
449 	if (fd == -1)
450 		return -1;
451 
452 	log_debug("%s: opened socket (%d) for %s", __func__,
453 	    fd, a->ifname);
454 
455 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &o_val,
456 	    sizeof(int)) == -1) {
457 		log_warn("%s: setsockopt error", __func__);
458 		close(fd);
459 		return -1;
460 	}
461 
462 	/* non-blocking */
463 	flags = fcntl(fd, F_GETFL);
464 	flags |= O_NONBLOCK;
465 	if (fcntl(fd, F_SETFL, flags) == -1) {
466 		log_info("%s: could not enable non-blocking I/O", __func__);
467 		close(fd);
468 		return -1;
469 	}
470 
471 	if (bind(fd, (struct sockaddr *)&a->ss, a->slen) == -1) {
472 		close(fd);
473 		log_info("%s: can't bind to port %d", __func__, a->port);
474 		return -1;
475 	}
476 
477 	if (listen(fd, SOMAXCONN) == -1) {
478 		log_warn("%s, unable to listen on socket", __func__);
479 		close(fd);
480 		return -1;
481 	}
482 
483 	return (fd);
484 }
485 
486 static int
487 sockets_accept_reserve(int sockfd, struct sockaddr *addr, socklen_t *addrlen,
488     int reserve, volatile int *counter)
489 {
490 	int ret;
491 
492 	if (getdtablecount() + reserve +
493 	    ((*counter + 1) * FD_NEEDED) >= getdtablesize()) {
494 		log_debug("inflight fds exceeded");
495 		errno = EMFILE;
496 		return -1;
497 	}
498 
499 	if ((ret = accept4(sockfd, addr, addrlen,
500 	    SOCK_NONBLOCK | SOCK_CLOEXEC)) > -1) {
501 		(*counter)++;
502 		log_debug("inflight incremented, now %d", *counter);
503 	}
504 
505 	return ret;
506 }
507 
508 static void
509 sockets_accept_paused(int fd, short events, void *arg)
510 {
511 	struct socket *sock = (struct socket *)arg;
512 
513 	event_add(&sock->ev, NULL);
514 }
515 
516 void
517 sockets_socket_accept(int fd, short event, void *arg)
518 {
519 	struct socket *sock = (struct socket *)arg;
520 	struct sockaddr_storage ss;
521 	struct timeval backoff;
522 	struct request *c = NULL;
523 	socklen_t len;
524 	int s;
525 
526 	backoff.tv_sec = 1;
527 	backoff.tv_usec = 0;
528 
529 	event_add(&sock->ev, NULL);
530 	if (event & EV_TIMEOUT)
531 		return;
532 
533 	len = sizeof(ss);
534 
535 	s = sockets_accept_reserve(fd, (struct sockaddr *)&ss, &len,
536 	    FD_RESERVE, &cgi_inflight);
537 
538 	if (s == -1) {
539 		switch (errno) {
540 		case EINTR:
541 		case EWOULDBLOCK:
542 		case ECONNABORTED:
543 			return;
544 		case EMFILE:
545 		case ENFILE:
546 			event_del(&sock->ev);
547 			evtimer_add(&sock->pause, &backoff);
548 			return;
549 		default:
550 			log_warn("%s: accept", __func__);
551 		}
552 	}
553 
554 	if (client_cnt > GOTWEBD_MAXCLIENTS)
555 		goto err;
556 
557 	c = calloc(1, sizeof(struct request));
558 	if (c == NULL) {
559 		log_warn("%s", __func__);
560 		close(s);
561 		cgi_inflight--;
562 		return;
563 	}
564 
565 	c->tp = template(c, &fcgi_write, c->outbuf, sizeof(c->outbuf));
566 	if (c->tp == NULL) {
567 		log_warn("%s", __func__);
568 		close(s);
569 		cgi_inflight--;
570 		free(c);
571 		return;
572 	}
573 
574 	c->fd = s;
575 	c->sock = sock;
576 	memcpy(c->priv_fd, sock->priv_fd, sizeof(c->priv_fd));
577 	c->buf_pos = 0;
578 	c->buf_len = 0;
579 	c->request_started = 0;
580 	c->sock->client_status = CLIENT_CONNECT;
581 
582 	event_set(&c->ev, s, EV_READ|EV_PERSIST, fcgi_request, c);
583 	event_add(&c->ev, NULL);
584 
585 	evtimer_set(&c->tmo, fcgi_timeout, c);
586 	evtimer_add(&c->tmo, &timeout);
587 
588 	client_cnt++;
589 
590 	return;
591 err:
592 	cgi_inflight--;
593 	close(s);
594 	if (c != NULL)
595 		free(c);
596 }
597 
598 static void
599 sockets_rlimit(int maxfd)
600 {
601 	struct rlimit rl;
602 
603 	if (getrlimit(RLIMIT_NOFILE, &rl) == -1)
604 		fatal("%s: failed to get resource limit", __func__);
605 	log_debug("%s: max open files %llu", __func__,
606 	    (unsigned long long)rl.rlim_max);
607 
608 	/*
609 	 * Allow the maximum number of open file descriptors for this
610 	 * login class (which should be the class "daemon" by default).
611 	 */
612 	if (maxfd == -1)
613 		rl.rlim_cur = rl.rlim_max;
614 	else
615 		rl.rlim_cur = MAXIMUM(rl.rlim_max, (rlim_t)maxfd);
616 	if (setrlimit(RLIMIT_NOFILE, &rl) == -1)
617 		fatal("%s: failed to set resource limit", __func__);
618 }