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 <limits.h>
24 #include <pwd.h>
25 #include <signal.h>
26 #include <string.h>
27 
28 volatile sig_atomic_t hupped;
29 
30 struct vhost hosts[HOSTSLEN];
31 
32 int exfd, logfd, sock4, sock6;
33 
34 struct imsgbuf logpibuf, logcibuf;
35 
36 const char *config_path, *certs_dir, *hostname;
37 
38 struct conf conf;
39 
40 struct tls_config *tlsconf;
41 struct tls *ctx;
42 
43 void
44 sig_handler(int sig)
45 {
46 	(void)sig;
47 
48 	hupped = sig == SIGHUP;
49 }
50 
51 /* XXX: create recursively */
52 void
53 mkdirs(const char *path)
54 {
55 	if (mkdir(path, 0755) == -1 && errno != EEXIST)
56 		fatal("can't mkdir %s: %s", path, strerror(errno));
57 }
58 
59 /* $XDG_DATA_HOME/gmid */
60 char *
61 data_dir(void)
62 {
63 	const char *home, *xdg;
64 	char *t;
65 
66 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
67 		if ((home = getenv("HOME")) == NULL)
68 			errx(1, "XDG_DATA_HOME and HOME both empty");
69 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
70 			err(1, "asprintf");
71 		mkdirs(t);
72 		return t;
73 	}
74 
75 	if (asprintf(&t, "%s/gmid", xdg) == -1)
76 		err(1, "asprintf");
77 	mkdirs(t);
78 	return t;
79 }
80 
81 void
82 load_local_cert(const char *hostname, const char *dir)
83 {
84 	char *cert, *key;
85 
86 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
87 		errx(1, "asprintf");
88 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
89 		errx(1, "asprintf");
90 
91 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
92 		gen_certificate(hostname, cert, key);
93 
94 	hosts[0].cert = cert;
95 	hosts[0].key = key;
96 	hosts[0].domain = hostname;
97 }
98 
99 void
100 load_vhosts(void)
101 {
102 	struct vhost *h;
103 
104 	for (h = hosts; h->domain != NULL; ++h) {
105 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
106 			fatal("open %s for domain %s", h->dir, h->domain);
107 	}
108 }
109 
110 int
111 make_socket(int port, int family)
112 {
113 	int sock, v;
114 	struct sockaddr_in addr4;
115 	struct sockaddr_in6 addr6;
116 	struct sockaddr *addr;
117 	socklen_t len;
118 
119         switch (family) {
120 	case AF_INET:
121 		bzero(&addr4, sizeof(addr4));
122 		addr4.sin_family = family;
123 		addr4.sin_port = htons(port);
124 		addr4.sin_addr.s_addr = INADDR_ANY;
125 		addr = (struct sockaddr*)&addr4;
126 		len = sizeof(addr4);
127 		break;
128 
129 	case AF_INET6:
130 		bzero(&addr6, sizeof(addr6));
131 		addr6.sin6_family = AF_INET6;
132 		addr6.sin6_port = htons(port);
133 		addr6.sin6_addr = in6addr_any;
134 		addr = (struct sockaddr*)&addr6;
135 		len = sizeof(addr6);
136 		break;
137 
138 	default:
139 		/* unreachable */
140 		abort();
141 	}
142 
143 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
144 		fatal("socket: %s", strerror(errno));
145 
146 	v = 1;
147 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
148 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
149 
150 	v = 1;
151 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
152 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
153 
154 	mark_nonblock(sock);
155 
156 	if (bind(sock, addr, len) == -1)
157 		fatal("bind: %s", strerror(errno));
158 
159 	if (listen(sock, 16) == -1)
160 		fatal("listen: %s", strerror(errno));
161 
162 	return sock;
163 }
164 
165 void
166 setup_tls(void)
167 {
168 	struct vhost *h;
169 
170 	if ((tlsconf = tls_config_new()) == NULL)
171 		fatal("tls_config_new");
172 
173 	/* optionally accept client certs, but don't try to verify them */
174 	tls_config_verify_client_optional(tlsconf);
175 	tls_config_insecure_noverifycert(tlsconf);
176 
177 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
178 		fatal("tls_config_set_protocols");
179 
180 	if ((ctx = tls_server()) == NULL)
181 		fatal("tls_server failure");
182 
183 	/* we need to set something, then we can add how many key we want */
184 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
185 		fatal("tls_config_set_keypair_file failed for (%s, %s)",
186 		    hosts->cert, hosts->key);
187 
188 	for (h = &hosts[1]; h->domain != NULL; ++h) {
189 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
190 			fatal("failed to load the keypair (%s, %s)",
191 			    h->cert, h->key);
192 	}
193 
194 	if (tls_configure(ctx, tlsconf) == -1)
195 		fatal("tls_configure: %s", tls_error(ctx));
196 }
197 
198 static int
199 listener_main(void)
200 {
201 	drop_priv();
202 	unblock_signals();
203 	load_default_mime(&conf.mime);
204 	load_vhosts();
205 	loop(ctx, sock4, sock6);
206 	return 0;
207 }
208 
209 void
210 init_config(void)
211 {
212 	size_t i;
213 
214 	bzero(hosts, sizeof(hosts));
215 	for (i = 0; i < HOSTSLEN; ++i)
216 		hosts[i].dirfd = -1;
217 
218 	conf.port = 1965;
219 	conf.ipv6 = 0;
220 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
221 
222 	init_mime(&conf.mime);
223 
224 	conf.chroot = NULL;
225 	conf.user = NULL;
226 
227 	/* we'll change this to 0 when running without config. */
228 	conf.prefork = 3;
229 }
230 
231 void
232 free_config(void)
233 {
234 	struct vhost *h;
235 	struct location *l;
236 
237 	free(conf.chroot);
238 	free(conf.user);
239 	memset(&conf, 0, sizeof(conf));
240 
241 	for (h = hosts; h->domain != NULL; ++h) {
242 		free((char*)h->domain);
243 		free((char*)h->cert);
244 		free((char*)h->key);
245 		free((char*)h->dir);
246 		free((char*)h->cgi);
247 		free((char*)h->entrypoint);
248 
249 		for (l = h->locations; l->match != NULL; ++l) {
250 			free((char*)l->match);
251 			free((char*)l->lang);
252 			free((char*)l->default_mime);
253 			free((char*)l->index);
254 			free((char*)l->block_fmt);
255 		}
256 	}
257 	memset(hosts, 0, sizeof(hosts));
258 
259 	tls_free(ctx);
260 	tls_config_free(tlsconf);
261 }
262 
263 static void
264 wait_sighup(void)
265 {
266 	sigset_t mask;
267 	int signo;
268 
269 	sigemptyset(&mask);
270 	sigaddset(&mask, SIGHUP);
271 	sigwait(&mask, &signo);
272 }
273 
274 void
275 drop_priv(void)
276 {
277 	struct passwd *pw = NULL;
278 
279 	if (conf.chroot != NULL && conf.user == NULL)
280 		fatal("can't chroot without an user to switch to after.");
281 
282 	if (conf.user != NULL) {
283 		if ((pw = getpwnam(conf.user)) == NULL)
284 			fatal("can't find user %s", conf.user);
285 	}
286 
287 	if (conf.chroot != NULL) {
288 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
289 			fatal("%s: %s", conf.chroot, strerror(errno));
290 	}
291 
292 	if (pw != NULL) {
293 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
294 			fatal("setresuid(%d): %s", pw->pw_uid,
295 			    strerror(errno));
296 	}
297 
298 	if (getuid() == 0)
299 		log_warn(NULL, "not a good idea to run a network daemon as root");
300 }
301 
302 static int
303 spawn_listeners(int *p)
304 {
305 	int i;
306 
307 	close(p[0]);
308 	exfd = p[1];
309 
310 	for (i = 0; i < conf.prefork -1; ++i) {
311 		switch (fork()) {
312 		case -1:
313 			fatal("fork: %s", strerror(errno));
314 		case 0:		/* child */
315 			setproctitle("server(%d)", i+1);
316 			return listener_main();
317 		}
318 	}
319 
320 	if (conf.prefork == 0)
321 		setproctitle("server");
322 	else
323 		setproctitle("server(%d)", conf.prefork);
324 	return listener_main();
325 }
326 
327 static void
328 usage(const char *me)
329 {
330 	fprintf(stderr,
331 	    "USAGE: %s [-fn] [-c config] | [-6h] [-d certs-dir] [-H host]"
332 	    "       [-p port] [-x cgi] [dir]\n",
333 	    me);
334 }
335 
336 static void
337 logger_init(void)
338 {
339 	int p[2];
340 
341 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
342 		err(1, "socketpair");
343 
344 	switch (fork()) {
345 	case -1:
346 		err(1, "fork");
347 	case 0:
348 		logfd = p[1];
349 		close(p[0]);
350 		setproctitle("logger");
351 		imsg_init(&logcibuf, p[1]);
352 		drop_priv();
353 		_exit(logger_main(p[1], &logcibuf));
354 	default:
355 		logfd = p[0];
356 		close(p[1]);
357 		imsg_init(&logpibuf, p[0]);
358 		return;
359 	}
360 }
361 
362 
363 static int
364 serve(int argc, char **argv, int *p)
365 {
366 	char path[PATH_MAX];
367 
368 	if (config_path == NULL) {
369 		if (hostname == NULL)
370 			hostname = "localhost";
371 		if (certs_dir == NULL)
372 			certs_dir = data_dir();
373 		load_local_cert(hostname, certs_dir);
374 
375 		hosts[0].domain = "*";
376 		hosts[0].locations[0].auto_index = 1;
377 		hosts[0].locations[0].match = "*";
378 
379 		switch (argc) {
380 		case 0:
381 			hosts[0].dir = getcwd(path, sizeof(path));
382 			break;
383 		case 1:
384 			hosts[0].dir = absolutify_path(argv[0]);
385 			break;
386 		default:
387 			usage(getprogname());
388 			return 1;
389 		}
390 
391 		log_notice(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
392 	}
393 
394 	/* setup tls before dropping privileges: we don't want user
395 	 * to put private certs inside the chroot. */
396 	setup_tls();
397 
398 	switch (fork()) {
399 	case -1:
400 		fatal("fork: %s", strerror(errno));
401 
402 	case 0:			/* child */
403 		return spawn_listeners(p);
404 
405 	default:		/* parent */
406 		setproctitle("executor");
407 		close(p[1]);
408 		exfd = p[0];
409 		drop_priv();
410 		unblock_signals();
411 		return executor_main();
412 	}
413 }
414 
415 int
416 main(int argc, char **argv)
417 {
418 	int ch, p[2];
419 	int conftest = 0, configless = 0;
420 	int old_ipv6, old_port;
421 
422 	init_config();
423 
424 	while ((ch = getopt(argc, argv, "6c:d:fH:hnp:vx:")) != -1) {
425 		switch (ch) {
426 		case '6':
427 			conf.ipv6 = 1;
428 			configless = 1;
429 			break;
430 
431 		case 'c':
432 			config_path = absolutify_path(optarg);
433 			break;
434 
435 		case 'd':
436 			certs_dir = optarg;
437 			configless = 1;
438 			break;
439 
440 		case 'f':
441 			conf.foreground = 1;
442 			break;
443 
444 		case 'H':
445 			hostname = optarg;
446 			configless = 1;
447 			break;
448 
449 		case 'h':
450 			usage(*argv);
451 			return 0;
452 
453 		case 'n':
454 			conftest = 1;
455 			break;
456 
457 		case 'p':
458 			conf.port = parse_portno(optarg);
459 			configless = 1;
460 			break;
461 
462 		case 'v':
463 			conf.verbose++;
464 			break;
465 
466 		case 'x':
467 			/* drop the starting / (if any) */
468 			if (*optarg == '/')
469 				optarg++;
470 			hosts[0].cgi = optarg;
471 			configless = 1;
472 			break;
473 
474 		default:
475 			usage(*argv);
476 			return 1;
477 		}
478 	}
479 	argc -= optind;
480 	argv += optind;
481 
482 	if (config_path == NULL) {
483 		configless = 1;
484 		conf.foreground = 1;
485 		conf.prefork = 0;
486 		conf.verbose++;
487 	}
488 
489 	if (config_path != NULL && (argc > 0 || configless))
490 		err(1, "can't specify options in config mode.");
491 
492 	if (conftest) {
493 		parse_conf(config_path);
494 		puts("config OK");
495 		return 0;
496 	}
497 
498 	signal(SIGPIPE, SIG_IGN);
499 	signal(SIGCHLD, SIG_IGN);
500 
501 #ifdef SIGINFO
502 	signal(SIGINFO, sig_handler);
503 #endif
504 	signal(SIGUSR2, sig_handler);
505 	signal(SIGHUP, sig_handler);
506 
507 	if (!conf.foreground && !configless) {
508 		if (daemon(1, 1) == -1)
509 			err(1, "daemon");
510 	}
511 
512 	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
513 	    PF_UNSPEC, p) == -1)
514 		err(1, "socketpair");
515 
516 	if (config_path != NULL)
517 		parse_conf(config_path);
518 
519 	logger_init();
520 
521 	sock4 = make_socket(conf.port, AF_INET);
522 	sock6 = -1;
523 	if (conf.ipv6)
524 		sock6 = make_socket(conf.port, AF_INET6);
525 
526 	if (configless)
527 		return serve(argc, argv, p);
528 
529 	/* wait a sighup and reload the daemon */
530 	for (;;) {
531 		block_signals();
532 
533 		hupped = 0;
534 		switch (fork()) {
535 		case -1:
536 			fatal("fork: %s", strerror(errno));
537 		case 0:
538 			return serve(argc, argv, p);
539 		}
540 
541 		close(p[0]);
542 		close(p[1]);
543 
544 		wait_sighup();
545 		unblock_signals();
546 		log_info(NULL, "reloading configuration %s", config_path);
547 
548 		old_ipv6 = conf.ipv6;
549 		old_port = conf.port;
550 
551 		free_config();
552 		init_config();
553 		parse_conf(config_path);
554 
555 		if (old_port != conf.port) {
556 			close(sock4);
557 			close(sock6);
558 			sock4 = -1;
559 			sock6 = -1;
560 		}
561 
562 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
563 			close(sock6);
564 			sock6 = -1;
565 		}
566 
567 		if (sock4 == -1)
568 			sock4 = make_socket(conf.port, AF_INET);
569 		if (sock6 == -1 && conf.ipv6)
570 			sock6 = make_socket(conf.port, AF_INET6);
571 
572 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
573 		    PF_UNSPEC, p) == -1)
574 			fatal("socketpair: %s", strerror(errno));
575 	}
576 }