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