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 			TAILQ_REMOVE(&h->env, e, envs);
285 
286 			free(e->name);
287 			free(e->value);
288 			free(e);
289 		}
290 
291 		TAILQ_FOREACH_SAFE(a, &h->aliases, aliases, ta) {
292 			TAILQ_REMOVE(&h->aliases, a, aliases);
293 
294 			free(a->alias);
295 			free(a);
296 		}
297 
298 		free((char*)h->domain);
299 		free((char*)h->cert);
300 		free((char*)h->key);
301 		free((char*)h->cgi);
302 		free((char*)h->entrypoint);
303 
304 		TAILQ_REMOVE(&hosts, h, vhosts);
305 		free(h);
306 	}
307 
308 	for (i = 0; i < FCGI_MAX; ++i) {
309 		if (fcgi[i].path == NULL && fcgi[i].prog == NULL)
310 			break;
311 		free(fcgi[i].path);
312 		free(fcgi[i].port);
313 		free(fcgi[i].prog);
314 	}
315 
316 	tls_free(ctx);
317 	tls_config_free(tlsconf);
318 }
319 
320 static int
321 wait_signal(void)
322 {
323 	sigset_t mask;
324 	int signo;
325 
326 	sigemptyset(&mask);
327 	sigaddset(&mask, SIGHUP);
328 	sigaddset(&mask, SIGINT);
329 	sigaddset(&mask, SIGTERM);
330 	sigwait(&mask, &signo);
331 
332 	return signo == SIGHUP;
333 }
334 
335 void
336 drop_priv(void)
337 {
338 	struct passwd *pw = NULL;
339 
340 	if (conf.chroot != NULL && conf.user == NULL)
341 		fatal("can't chroot without an user to switch to after.");
342 
343 	if (conf.user != NULL) {
344 		if ((pw = getpwnam(conf.user)) == NULL)
345 			fatal("can't find user %s", conf.user);
346 	}
347 
348 	if (conf.chroot != NULL) {
349 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
350 			fatal("%s: %s", conf.chroot, strerror(errno));
351 	}
352 
353 	if (pw != NULL) {
354 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
355 			fatal("setresuid(%d): %s", pw->pw_uid,
356 			    strerror(errno));
357 	}
358 
359 	if (getuid() == 0)
360 		log_warn(NULL, "not a good idea to run a network daemon as root");
361 }
362 
363 static void
364 usage(const char *me)
365 {
366 	fprintf(stderr,
367 	    "USAGE: %s [-fn] [-c config] [-P pidfile] | [-6h] [-d certs-dir] [-H host]\n"
368 	    "       [-p port] [-x cgi] [dir]\n",
369 	    me);
370 }
371 
372 static void
373 logger_init(void)
374 {
375 	int p[2];
376 
377 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
378 		err(1, "socketpair");
379 
380 	switch (fork()) {
381 	case -1:
382 		err(1, "fork");
383 	case 0:
384 		signal(SIGHUP, SIG_IGN);
385 		close(p[0]);
386 		setproctitle("logger");
387 		imsg_init(&logibuf, p[1]);
388 		drop_priv();
389 		_exit(logger_main(p[1], &logibuf));
390 	default:
391 		close(p[1]);
392 		imsg_init(&logibuf, p[0]);
393 		return;
394 	}
395 }
396 
397 static int
398 serve(int argc, char **argv, struct imsgbuf *ibuf)
399 {
400 	char		 path[PATH_MAX];
401 	int		 i, p[2];
402 	struct vhost	*h;
403 	struct location	*l;
404 
405         if (config_path == NULL) {
406 		if (hostname == NULL)
407 			hostname = "localhost";
408 		if (certs_dir == NULL)
409 			certs_dir = data_dir();
410 		load_local_cert(hostname, certs_dir);
411 
412 		h = TAILQ_FIRST(&hosts);
413 		h->domain = "*";
414 
415 		l = TAILQ_FIRST(&h->locations);
416 		l->auto_index = 1;
417 		l->match = "*";
418 
419 		switch (argc) {
420 		case 0:
421 			l->dir = getcwd(path, sizeof(path));
422 			break;
423 		case 1:
424 			l->dir = absolutify_path(argv[0]);
425 			break;
426 		default:
427 			usage(getprogname());
428 			return 1;
429 		}
430 
431 		log_notice(NULL, "serving %s on port %d", l->dir, conf.port);
432 	}
433 
434 	/* setup tls before dropping privileges: we don't want user
435 	 * to put private certs inside the chroot. */
436 	setup_tls();
437 
438 	for (i = 0; i < conf.prefork; ++i) {
439 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
440 		    PF_UNSPEC, p) == -1)
441 			fatal("socketpair: %s", strerror(errno));
442 
443 		switch (fork()) {
444 		case -1:
445 			fatal("fork: %s", strerror(errno));
446 		case 0:		/* child */
447 			close(p[0]);
448 			imsg_init(&exibuf, p[1]);
449 			setproctitle("server");
450 			_exit(listener_main(&exibuf));
451 		default:
452 			close(p[1]);
453 			imsg_init(&servibuf[i], p[0]);
454 		}
455 	}
456 
457 	setproctitle("executor");
458 	drop_priv();
459 	_exit(executor_main(ibuf));
460 }
461 
462 static int
463 write_pidfile(const char *pidfile)
464 {
465 	struct flock	lock;
466 	int		fd;
467 
468 	if (pidfile == NULL)
469 		return -1;
470 
471 	if ((fd = open(pidfile, O_WRONLY|O_CREAT|O_CLOEXEC, 0600)) == -1)
472 		fatal("can't open pidfile %s: %s", pidfile, strerror(errno));
473 
474 	lock.l_start = 0;
475 	lock.l_len = 0;
476 	lock.l_type = F_WRLCK;
477 	lock.l_whence = SEEK_SET;
478 
479 	if (fcntl(fd, F_SETLK, &lock) == -1)
480 		fatal("can't lock %s, gmid is already running?", pidfile);
481 
482 	if (ftruncate(fd, 0) == -1)
483 		fatal("ftruncate: %s: %s", pidfile, strerror(errno));
484 
485 	dprintf(fd, "%d\n", getpid());
486 
487 	return fd;
488 }
489 
490 static void
491 setup_configless(int argc, char **argv, const char *cgi)
492 {
493 	struct vhost	*host;
494 	struct location	*loc;
495 
496 	host = xcalloc(1, sizeof(*host));
497 	host->cgi = cgi;
498 	TAILQ_INSERT_HEAD(&hosts, host, vhosts);
499 
500 	loc = xcalloc(1, sizeof(*loc));
501 	TAILQ_INSERT_HEAD(&host->locations, loc, locations);
502 
503 	serve(argc, argv, NULL);
504 	imsg_compose(&logibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
505 	imsg_flush(&logibuf);
506 }
507 
508 int
509 main(int argc, char **argv)
510 {
511 	struct imsgbuf exibuf;
512 	int ch, conftest = 0, configless = 0;
513 	int pidfd, old_ipv6, old_port;
514 
515 	init_config();
516 
517 	while ((ch = getopt(argc, argv, "6c:d:fH:hnP:p:vx:")) != -1) {
518 		switch (ch) {
519 		case '6':
520 			conf.ipv6 = 1;
521 			configless = 1;
522 			break;
523 
524 		case 'c':
525 			config_path = absolutify_path(optarg);
526 			break;
527 
528 		case 'd':
529 			certs_dir = optarg;
530 			configless = 1;
531 			break;
532 
533 		case 'f':
534 			conf.foreground = 1;
535 			break;
536 
537 		case 'H':
538 			hostname = optarg;
539 			configless = 1;
540 			break;
541 
542 		case 'h':
543 			usage(*argv);
544 			return 0;
545 
546 		case 'n':
547 			conftest = 1;
548 			break;
549 
550 		case 'P':
551 			pidfile = optarg;
552 			break;
553 
554 		case 'p':
555 			conf.port = parse_portno(optarg);
556 			configless = 1;
557 			break;
558 
559 		case 'v':
560 			conf.verbose++;
561 			break;
562 
563 		case 'x':
564 			/* drop the starting / (if any) */
565 			if (*optarg == '/')
566 				optarg++;
567 			cgi = optarg;
568 			configless = 1;
569 			break;
570 
571 		default:
572 			usage(*argv);
573 			return 1;
574 		}
575 	}
576 	argc -= optind;
577 	argv += optind;
578 
579 	if (config_path == NULL) {
580 		configless = 1;
581 		conf.foreground = 1;
582 		conf.prefork = 1;
583 		conf.verbose++;
584 	}
585 
586 	if (config_path != NULL && (argc > 0 || configless))
587 		errx(1, "can't specify options in config mode.");
588 
589 	if (conftest) {
590 		parse_conf(config_path);
591 		puts("config OK");
592 		return 0;
593 	}
594 
595 	if (!conf.foreground && !configless) {
596 		if (daemon(1, 1) == -1)
597 			err(1, "daemon");
598 	}
599 
600 	if (config_path != NULL)
601 		parse_conf(config_path);
602 
603 	logger_init();
604 
605 	sock4 = make_socket(conf.port, AF_INET);
606 	sock6 = -1;
607 	if (conf.ipv6)
608 		sock6 = make_socket(conf.port, AF_INET6);
609 
610 	signal(SIGPIPE, SIG_IGN);
611 	signal(SIGCHLD, SIG_IGN);
612 
613 	if (configless) {
614 		setup_configless(argc, argv, cgi);
615 		return 0;
616 	}
617 
618 	pidfd = write_pidfile(pidfile);
619 
620 	/* Linux seems to call the event handlers even when we're
621 	 * doing a sigwait.  These dummy handlers are here to avoid
622 	 * being terminated on SIGHUP, SIGINT or SIGTERM. */
623 	signal(SIGHUP, dummy_handler);
624 	signal(SIGINT, dummy_handler);
625 	signal(SIGTERM, dummy_handler);
626 
627 	/* wait a sighup and reload the daemon */
628 	for (;;) {
629 		int p[2];
630 
631 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
632 		    PF_UNSPEC, p) == -1)
633 			fatal("socketpair: %s", strerror(errno));
634 
635 		switch (fork()) {
636 		case -1:
637 			fatal("fork: %s", strerror(errno));
638 		case 0:
639 			close(p[0]);
640 			imsg_init(&exibuf, p[1]);
641 			_exit(serve(argc, argv, &exibuf));
642 		}
643 
644 		close(p[1]);
645 		imsg_init(&exibuf, p[0]);
646 
647 		if (!wait_signal())
648 			break;
649 
650 		log_info(NULL, "reloading configuration %s", config_path);
651 
652 		/* close the executor (it'll close the servers too) */
653 		imsg_compose(&exibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
654 		imsg_flush(&exibuf);
655 		close(p[0]);
656 
657 		old_ipv6 = conf.ipv6;
658 		old_port = conf.port;
659 
660 		free_config();
661 		init_config();
662 		parse_conf(config_path);
663 
664 		if (old_port != conf.port) {
665 			close(sock4);
666 			close(sock6);
667 			sock4 = -1;
668 			sock6 = -1;
669 		}
670 
671 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
672 			close(sock6);
673 			sock6 = -1;
674 		}
675 
676 		if (sock4 == -1)
677 			sock4 = make_socket(conf.port, AF_INET);
678 		if (sock6 == -1 && conf.ipv6)
679 			sock6 = make_socket(conf.port, AF_INET6);
680 	}
681 
682 	imsg_compose(&exibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
683 	imsg_flush(&exibuf);
684 
685 	imsg_compose(&logibuf, IMSG_QUIT, 0, 0, -1, NULL, 0);
686 	imsg_flush(&logibuf);
687 
688 	if (pidfd != -1)
689 		close(pidfd);
690 
691 	return 0;
692 }