1 /*
2  * Copyright (c) 2020 Omar Polo <op@omarpolo.com>
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 "gmid.h"
18 
19 #include <sys/stat.h>
20 
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <libgen.h>
24 #include <limits.h>
25 #include <pwd.h>
26 #include <signal.h>
27 #include <string.h>
28 
29 struct fcgi fcgi[FCGI_MAX];
30 
31 struct vhosthead hosts;
32 
33 int sock4, sock6;
34 
35 struct imsgbuf logibuf, exibuf, servibuf[PROC_MAX];
36 
37 const char *config_path, *certs_dir, *hostname, *pidfile, *cgi;
38 
39 struct conf conf;
40 
41 struct tls_config *tlsconf;
42 struct tls *ctx;
43 
44 static void
45 dummy_handler(int signo)
46 {
47 	return;
48 }
49 
50 /* wrapper around dirname(3).  dn must be PATH_MAX+1 at least. */
51 static void
52 pdirname(const char *path, char *dn)
53 {
54 	char	 p[PATH_MAX+1];
55 	char	*t;
56 
57 	strlcpy(p, path, sizeof(p));
58 	t = dirname(p);
59 	memmove(dn, t, strlen(t)+1);
60 }
61 
62 static void
63 mkdirs(const char *path, mode_t mode)
64 {
65 	char	dname[PATH_MAX+1];
66 
67 	pdirname(path, dname);
68 	if (!strcmp(dname, "/"))
69 		return;
70 	mkdirs(dname, mode);
71 	if (mkdir(path, mode) != 0 && errno != EEXIST)
72 		fatal("can't mkdir %s: %s", path, strerror(errno));
73 }
74 
75 /* $XDG_DATA_HOME/gmid */
76 char *
77 data_dir(void)
78 {
79 	const char *home, *xdg;
80 	char *t;
81 
82 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
83 		if ((home = getenv("HOME")) == NULL)
84 			errx(1, "XDG_DATA_HOME and HOME both empty");
85 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
86 			err(1, "asprintf");
87 	} else {
88 		if (asprintf(&t, "%s/gmid", xdg) == -1)
89 			err(1, "asprintf");
90 	}
91 
92 	mkdirs(t, 0755);
93 	return t;
94 }
95 
96 void
97 load_local_cert(const char *hostname, const char *dir)
98 {
99 	char *cert, *key;
100 	struct vhost *h;
101 
102 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
103 		errx(1, "asprintf");
104 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
105 		errx(1, "asprintf");
106 
107 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
108 		gen_certificate(hostname, cert, key);
109 
110 	h = TAILQ_FIRST(&hosts);
111 	h->cert = cert;
112 	h->key = key;
113 	h->domain = hostname;
114 }
115 
116 void
117 load_vhosts(void)
118 {
119 	struct vhost	*h;
120 	struct location	*l;
121 
122 	TAILQ_FOREACH(h, &hosts, vhosts) {
123 		TAILQ_FOREACH(l, &h->locations, locations) {
124 			if (l->dir == NULL)
125 				continue;
126 			if ((l->dirfd = open(l->dir, O_RDONLY | O_DIRECTORY)) == -1)
127 				fatal("open %s for domain %s", l->dir, h->domain);
128 		}
129 	}
130 }
131 
132 int
133 make_socket(int port, int family)
134 {
135 	int sock, v;
136 	struct sockaddr_in addr4;
137 	struct sockaddr_in6 addr6;
138 	struct sockaddr *addr;
139 	socklen_t len;
140 
141         switch (family) {
142 	case AF_INET:
143 		bzero(&addr4, sizeof(addr4));
144 		addr4.sin_family = family;
145 		addr4.sin_port = htons(port);
146 		addr4.sin_addr.s_addr = INADDR_ANY;
147 		addr = (struct sockaddr*)&addr4;
148 		len = sizeof(addr4);
149 		break;
150 
151 	case AF_INET6:
152 		bzero(&addr6, sizeof(addr6));
153 		addr6.sin6_family = AF_INET6;
154 		addr6.sin6_port = htons(port);
155 		addr6.sin6_addr = in6addr_any;
156 		addr = (struct sockaddr*)&addr6;
157 		len = sizeof(addr6);
158 		break;
159 
160 	default:
161 		/* unreachable */
162 		abort();
163 	}
164 
165 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
166 		fatal("socket: %s", strerror(errno));
167 
168 	v = 1;
169 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
170 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
171 
172 	v = 1;
173 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
174 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
175 
176 	mark_nonblock(sock);
177 
178 	if (bind(sock, addr, len) == -1)
179 		fatal("bind: %s", strerror(errno));
180 
181 	if (listen(sock, 16) == -1)
182 		fatal("listen: %s", strerror(errno));
183 
184 	return sock;
185 }
186 
187 void
188 setup_tls(void)
189 {
190 	struct vhost *h;
191 
192 	if ((tlsconf = tls_config_new()) == NULL)
193 		fatal("tls_config_new");
194 
195 	/* optionally accept client certs, but don't try to verify them */
196 	tls_config_verify_client_optional(tlsconf);
197 	tls_config_insecure_noverifycert(tlsconf);
198 
199 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
200 		fatal("tls_config_set_protocols");
201 
202 	if ((ctx = tls_server()) == NULL)
203 		fatal("tls_server failure");
204 
205 	h = TAILQ_FIRST(&hosts);
206 
207 	/* we need to set something, then we can add how many key we want */
208 	if (tls_config_set_keypair_file(tlsconf, h->cert, h->key))
209 		fatal("tls_config_set_keypair_file failed for (%s, %s)",
210 		    h->cert, h->key);
211 
212 	while ((h = TAILQ_NEXT(h, vhosts)) != NULL) {
213 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
214 			fatal("failed to load the keypair (%s, %s)",
215 			    h->cert, h->key);
216 	}
217 
218 	if (tls_configure(ctx, tlsconf) == -1)
219 		fatal("tls_configure: %s", tls_error(ctx));
220 }
221 
222 static int
223 listener_main(struct imsgbuf *ibuf)
224 {
225 	drop_priv();
226 	load_default_mime(&conf.mime);
227 	load_vhosts();
228 	loop(ctx, sock4, sock6, ibuf);
229 	return 0;
230 }
231 
232 void
233 init_config(void)
234 {
235 	TAILQ_INIT(&hosts);
236 
237 	conf.port = 1965;
238 	conf.ipv6 = 0;
239 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
240 
241 	init_mime(&conf.mime);
242 
243 	conf.chroot = NULL;
244 	conf.user = NULL;
245 
246 	conf.prefork = 3;
247 }
248 
249 void
250 free_config(void)
251 {
252 	struct vhost *h, *th;
253 	struct location *l, *tl;
254 	struct envlist *e, *te;
255 	struct alist *a, *ta;
256 	int v, i;
257 
258 	v = conf.verbose;
259 
260 	free(conf.chroot);
261 	free(conf.user);
262 	memset(&conf, 0, sizeof(conf));
263 
264 	conf.verbose = v;
265 
266 	TAILQ_FOREACH_SAFE(h, &hosts, vhosts, th) {
267 		TAILQ_FOREACH_SAFE(l, &h->locations, locations, tl) {
268 			TAILQ_REMOVE(&h->locations, l, locations);
269 
270 			free((char*)l->match);
271 			free((char*)l->lang);
272 			free((char*)l->default_mime);
273 			free((char*)l->index);
274 			free((char*)l->block_fmt);
275 			free((char*)l->dir);
276 
277 			if (l->dirfd != -1)
278 				close(l->dirfd);
279 
280 			free(l);
281 		}
282 
283 		TAILQ_FOREACH_SAFE(e, &h->env, envs, te) {
284 			free(e->name);
285 			free(e->value);
286 			free(e);
287 		}
288 
289 		TAILQ_FOREACH_SAFE(a, &h->aliases, aliases, ta) {
290 			free(a->alias);
291 			free(a);
292 		}
293 
294 		free((char*)h->domain);
295 		free((char*)h->cert);
296 		free((char*)h->key);
297 		free((char*)h->cgi);
298 		free((char*)h->entrypoint);
299 
300 		TAILQ_REMOVE(&hosts, h, vhosts);
301 		free(h);
302 	}
303 
304 	for (i = 0; i < FCGI_MAX; ++i) {
305 		if (fcgi[i].path == NULL && fcgi[i].prog == NULL)
306 			break;
307 		free(fcgi[i].path);
308 		free(fcgi[i].port);
309 		free(fcgi[i].prog);
310 	}
311 
312 	tls_free(ctx);
313 	tls_config_free(tlsconf);
314 }
315 
316 static int
317 wait_signal(void)
318 {
319 	sigset_t mask;
320 	int signo;
321 
322 	sigemptyset(&mask);
323 	sigaddset(&mask, SIGHUP);
324 	sigaddset(&mask, SIGINT);
325 	sigaddset(&mask, SIGTERM);
326 	sigwait(&mask, &signo);
327 
328 	return signo == SIGHUP;
329 }
330 
331 void
332 drop_priv(void)
333 {
334 	struct passwd *pw = NULL;
335 
336 	if (conf.chroot != NULL && conf.user == NULL)
337 		fatal("can't chroot without an user to switch to after.");
338 
339 	if (conf.user != NULL) {
340 		if ((pw = getpwnam(conf.user)) == NULL)
341 			fatal("can't find user %s", conf.user);
342 	}
343 
344 	if (conf.chroot != NULL) {
345 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
346 			fatal("%s: %s", conf.chroot, strerror(errno));
347 	}
348 
349 	if (pw != NULL) {
350 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
351 			fatal("setresuid(%d): %s", pw->pw_uid,
352 			    strerror(errno));
353 	}
354 
355 	if (getuid() == 0)
356 		log_warn(NULL, "not a good idea to run a network daemon as root");
357 }
358 
359 static void
360 usage(const char *me)
361 {
362 	fprintf(stderr,
363 	    "USAGE: %s [-fn] [-c config] [-P pidfile] | [-6h] [-d certs-dir] [-H host]\n"
364 	    "       [-p port] [-x cgi] [dir]\n",
365 	    me);
366 }
367 
368 static void
369 logger_init(void)
370 {
371 	int p[2];
372 
373 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
374 		err(1, "socketpair");
375 
376 	switch (fork()) {
377 	case -1:
378 		err(1, "fork");
379 	case 0:
380 		signal(SIGHUP, SIG_IGN);
381 		close(p[0]);
382 		setproctitle("logger");
383 		imsg_init(&logibuf, p[1]);
384 		drop_priv();
385 		_exit(logger_main(p[1], &logibuf));
386 	default:
387 		close(p[1]);
388 		imsg_init(&logibuf, p[0]);
389 		return;
390 	}
391 }
392 
393 static int
394 serve(int argc, char **argv, struct imsgbuf *ibuf)
395 {
396 	char		 path[PATH_MAX];
397 	int		 i, p[2];
398 	struct vhost	*h;
399 	struct location	*l;
400 
401         if (config_path == NULL) {
402 		if (hostname == NULL)
403 			hostname = "localhost";
404 		if (certs_dir == NULL)
405 			certs_dir = data_dir();
406 		load_local_cert(hostname, certs_dir);
407 
408 		h = TAILQ_FIRST(&hosts);
409 		h->domain = "*";
410 
411 		l = TAILQ_FIRST(&h->locations);
412 		l->auto_index = 1;
413 		l->match = "*";
414 
415 		switch (argc) {
416 		case 0:
417 			l->dir = getcwd(path, sizeof(path));
418 			break;
419 		case 1:
420 			l->dir = absolutify_path(argv[0]);
421 			break;
422 		default:
423 			usage(getprogname());
424 			return 1;
425 		}
426 
427 		log_notice(NULL, "serving %s on port %d", l->dir, conf.port);
428 	}
429 
430 	/* setup tls before dropping privileges: we don't want user
431 	 * to put private certs inside the chroot. */
432 	setup_tls();
433 
434 	for (i = 0; i < conf.prefork; ++i) {
435 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
436 		    PF_UNSPEC, p) == -1)
437 			fatal("socketpair: %s", strerror(errno));
438 
439 		switch (fork()) {
440 		case -1:
441 			fatal("fork: %s", strerror(errno));
442 		case 0:		/* child */
443 			close(p[0]);
444 			imsg_init(&exibuf, p[1]);
445 			setproctitle("server");
446 			_exit(listener_main(&exibuf));
447 		default:
448 			close(p[1]);
449 			imsg_init(&servibuf[i], p[0]);
450 		}
451 	}
452 
453 	setproctitle("executor");
454 	drop_priv();
455 	_exit(executor_main(ibuf));
456 }
457 
458 static int
459 write_pidfile(const char *pidfile)
460 {
461 	struct flock	lock;
462 	int		fd;
463 
464 	if (pidfile == NULL)
465 		return -1;
466 
467 	if ((fd = open(pidfile, O_WRONLY|O_CREAT|O_CLOEXEC, 0600)) == -1)
468 		fatal("can't open pidfile %s: %s", pidfile, strerror(errno));
469 
470 	lock.l_start = 0;
471 	lock.l_len = 0;
472 	lock.l_type = F_WRLCK;
473 	lock.l_whence = SEEK_SET;
474 
475 	if (fcntl(fd, F_SETLK, &lock) == -1)
476 		fatal("can't lock %s, gmid is already running?", pidfile);
477 
478 	if (ftruncate(fd, 0) == -1)
479 		fatal("ftruncate: %s: %s", pidfile, strerror(errno));
480 
481 	dprintf(fd, "%d\n", getpid());
482 
483 	return fd;
484 }
485 
486 static void
487 setup_configless(int argc, char **argv, const char *cgi)
488 {
489 	struct vhost	*host;
490 	struct location	*loc;
491 
492 	host = xcalloc(1, sizeof(*host));
493 	host->cgi = cgi;
494 	TAILQ_INSERT_HEAD(&hosts, host, vhosts);
495 
496 	loc = xcalloc(1, sizeof(*loc));
497 	TAILQ_INSERT_HEAD(&host->locations, loc, locations);
498 
499 	serve(argc, argv, NULL);
500 	imsg_compose(&logibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
501 	imsg_flush(&logibuf);
502 }
503 
504 int
505 main(int argc, char **argv)
506 {
507 	struct imsgbuf exibuf;
508 	int ch, conftest = 0, configless = 0;
509 	int pidfd, old_ipv6, old_port;
510 
511 	init_config();
512 
513 	while ((ch = getopt(argc, argv, "6c:d:fH:hnP:p:vx:")) != -1) {
514 		switch (ch) {
515 		case '6':
516 			conf.ipv6 = 1;
517 			configless = 1;
518 			break;
519 
520 		case 'c':
521 			config_path = absolutify_path(optarg);
522 			break;
523 
524 		case 'd':
525 			certs_dir = optarg;
526 			configless = 1;
527 			break;
528 
529 		case 'f':
530 			conf.foreground = 1;
531 			break;
532 
533 		case 'H':
534 			hostname = optarg;
535 			configless = 1;
536 			break;
537 
538 		case 'h':
539 			usage(*argv);
540 			return 0;
541 
542 		case 'n':
543 			conftest = 1;
544 			break;
545 
546 		case 'P':
547 			pidfile = optarg;
548 			break;
549 
550 		case 'p':
551 			conf.port = parse_portno(optarg);
552 			configless = 1;
553 			break;
554 
555 		case 'v':
556 			conf.verbose++;
557 			break;
558 
559 		case 'x':
560 			/* drop the starting / (if any) */
561 			if (*optarg == '/')
562 				optarg++;
563 			cgi = optarg;
564 			configless = 1;
565 			break;
566 
567 		default:
568 			usage(*argv);
569 			return 1;
570 		}
571 	}
572 	argc -= optind;
573 	argv += optind;
574 
575 	if (config_path == NULL) {
576 		configless = 1;
577 		conf.foreground = 1;
578 		conf.prefork = 1;
579 		conf.verbose++;
580 	}
581 
582 	if (config_path != NULL && (argc > 0 || configless))
583 		errx(1, "can't specify options in config mode.");
584 
585 	if (conftest) {
586 		parse_conf(config_path);
587 		puts("config OK");
588 		return 0;
589 	}
590 
591 	if (!conf.foreground && !configless) {
592 		if (daemon(1, 1) == -1)
593 			err(1, "daemon");
594 	}
595 
596 	if (config_path != NULL)
597 		parse_conf(config_path);
598 
599 	logger_init();
600 
601 	sock4 = make_socket(conf.port, AF_INET);
602 	sock6 = -1;
603 	if (conf.ipv6)
604 		sock6 = make_socket(conf.port, AF_INET6);
605 
606 	signal(SIGPIPE, SIG_IGN);
607 	signal(SIGCHLD, SIG_IGN);
608 
609 	if (configless) {
610 		setup_configless(argc, argv, cgi);
611 		return 0;
612 	}
613 
614 	pidfd = write_pidfile(pidfile);
615 
616 	/* Linux seems to call the event handlers even when we're
617 	 * doing a sigwait.  These dummy handlers are here to avoid
618 	 * being terminated on SIGHUP, SIGINT or SIGTERM. */
619 	signal(SIGHUP, dummy_handler);
620 	signal(SIGINT, dummy_handler);
621 	signal(SIGTERM, dummy_handler);
622 
623 	/* wait a sighup and reload the daemon */
624 	for (;;) {
625 		int p[2];
626 
627 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
628 		    PF_UNSPEC, p) == -1)
629 			fatal("socketpair: %s", strerror(errno));
630 
631 		switch (fork()) {
632 		case -1:
633 			fatal("fork: %s", strerror(errno));
634 		case 0:
635 			close(p[0]);
636 			imsg_init(&exibuf, p[1]);
637 			_exit(serve(argc, argv, &exibuf));
638 		}
639 
640 		close(p[1]);
641 		imsg_init(&exibuf, p[0]);
642 
643 		if (!wait_signal())
644 			break;
645 
646 		log_info(NULL, "reloading configuration %s", config_path);
647 
648 		/* close the executor (it'll close the servers too) */
649 		imsg_compose(&exibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
650 		imsg_flush(&exibuf);
651 		close(p[0]);
652 
653 		old_ipv6 = conf.ipv6;
654 		old_port = conf.port;
655 
656 		free_config();
657 		init_config();
658 		parse_conf(config_path);
659 
660 		if (old_port != conf.port) {
661 			close(sock4);
662 			close(sock6);
663 			sock4 = -1;
664 			sock6 = -1;
665 		}
666 
667 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
668 			close(sock6);
669 			sock6 = -1;
670 		}
671 
672 		if (sock4 == -1)
673 			sock4 = make_socket(conf.port, AF_INET);
674 		if (sock6 == -1 && conf.ipv6)
675 			sock6 = make_socket(conf.port, AF_INET6);
676 	}
677 
678 	imsg_compose(&exibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
679 	imsg_flush(&exibuf);
680 
681 	imsg_compose(&logibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
682 	imsg_flush(&logibuf);
683 
684 	if (pidfd != -1)
685 		close(pidfd);
686 
687 	return 0;
688 }