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 <sys/stat.h>
18 
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <limits.h>
22 #include <pwd.h>
23 #include <signal.h>
24 #include <string.h>
25 
26 #include "gmid.h"
27 
28 volatile sig_atomic_t hupped;
29 
30 struct vhost hosts[HOSTSLEN];
31 
32 int exfd, sock4, sock6;
33 
34 const char *config_path, *certs_dir, *hostname;
35 
36 struct conf conf;
37 
38 struct tls_config *tlsconf;
39 struct tls *ctx;
40 
41 void
42 sig_handler(int sig)
43 {
44 	(void)sig;
45 
46 	hupped = sig == SIGHUP;
47 }
48 
49 /* XXX: create recursively */
50 void
51 mkdirs(const char *path)
52 {
53 	if (mkdir(path, 0755) == -1 && errno != EEXIST)
54 		fatal("can't mkdir %s: %s", path, strerror(errno));
55 }
56 
57 /* $XDG_DATA_HOME/gmid */
58 char *
59 data_dir(void)
60 {
61 	const char *home, *xdg;
62 	char *t;
63 
64 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
65 		if ((home = getenv("HOME")) == NULL)
66 			errx(1, "XDG_DATA_HOME and HOME both empty");
67 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
68 			err(1, "asprintf");
69 		mkdirs(t);
70 		return t;
71 	}
72 
73 	if (asprintf(&t, "%s/gmid", xdg) == -1)
74 		err(1, "asprintf");
75 	mkdirs(t);
76 	return t;
77 }
78 
79 void
80 load_local_cert(const char *hostname, const char *dir)
81 {
82 	char *cert, *key;
83 
84 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
85 		errx(1, "asprintf");
86 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
87 		errx(1, "asprintf");
88 
89 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
90 		gen_certificate(hostname, cert, key);
91 
92 	hosts[0].cert = cert;
93 	hosts[0].key = key;
94 	hosts[0].domain = hostname;
95 }
96 
97 void
98 load_vhosts(void)
99 {
100 	struct vhost *h;
101 
102 	for (h = hosts; h->domain != NULL; ++h) {
103 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
104 			fatal("open %s for domain %s", h->dir, h->domain);
105 	}
106 }
107 
108 int
109 make_socket(int port, int family)
110 {
111 	int sock, v;
112 	struct sockaddr_in addr4;
113 	struct sockaddr_in6 addr6;
114 	struct sockaddr *addr;
115 	socklen_t len;
116 
117         switch (family) {
118 	case AF_INET:
119 		bzero(&addr4, sizeof(addr4));
120 		addr4.sin_family = family;
121 		addr4.sin_port = htons(port);
122 		addr4.sin_addr.s_addr = INADDR_ANY;
123 		addr = (struct sockaddr*)&addr4;
124 		len = sizeof(addr4);
125 		break;
126 
127 	case AF_INET6:
128 		bzero(&addr6, sizeof(addr6));
129 		addr6.sin6_family = AF_INET6;
130 		addr6.sin6_port = htons(port);
131 		addr6.sin6_addr = in6addr_any;
132 		addr = (struct sockaddr*)&addr6;
133 		len = sizeof(addr6);
134 		break;
135 
136 	default:
137 		/* unreachable */
138 		abort();
139 	}
140 
141 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
142 		fatal("socket: %s", strerror(errno));
143 
144 	v = 1;
145 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
146 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
147 
148 	v = 1;
149 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
150 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
151 
152 	mark_nonblock(sock);
153 
154 	if (bind(sock, addr, len) == -1)
155 		fatal("bind: %s", strerror(errno));
156 
157 	if (listen(sock, 16) == -1)
158 		fatal("listen: %s", strerror(errno));
159 
160 	return sock;
161 }
162 
163 void
164 setup_tls(void)
165 {
166 	struct vhost *h;
167 
168 	if ((tlsconf = tls_config_new()) == NULL)
169 		fatal("tls_config_new");
170 
171 	/* optionally accept client certs, but don't try to verify them */
172 	tls_config_verify_client_optional(tlsconf);
173 	tls_config_insecure_noverifycert(tlsconf);
174 
175 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
176 		fatal("tls_config_set_protocols");
177 
178 	if ((ctx = tls_server()) == NULL)
179 		fatal("tls_server failure");
180 
181 	/* we need to set something, then we can add how many key we want */
182 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
183 		fatal("tls_config_set_keypair_file failed for (%s, %s)",
184 		    hosts->cert, hosts->key);
185 
186 	for (h = &hosts[1]; h->domain != NULL; ++h) {
187 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
188 			fatal("failed to load the keypair (%s, %s)",
189 			    h->cert, h->key);
190 	}
191 
192 	if (tls_configure(ctx, tlsconf) == -1)
193 		fatal("tls_configure: %s", tls_error(ctx));
194 }
195 
196 static int
197 listener_main(void)
198 {
199 	drop_priv();
200 	unblock_signals();
201 	load_default_mime(&conf.mime);
202 	load_vhosts();
203 	sandbox();
204 	loop(ctx, sock4, sock6);
205 	return 0;
206 }
207 
208 void
209 init_config(void)
210 {
211 	size_t i;
212 
213 	bzero(hosts, sizeof(hosts));
214 	for (i = 0; i < HOSTSLEN; ++i)
215 		hosts[i].dirfd = -1;
216 
217 	conf.port = 1965;
218 	conf.ipv6 = 0;
219 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
220 
221 	init_mime(&conf.mime);
222 
223 	conf.chroot = NULL;
224 	conf.user = NULL;
225 
226 	/* we'll change this to 0 when running without config. */
227 	conf.prefork = 3;
228 }
229 
230 void
231 free_config(void)
232 {
233 	struct vhost *h;
234 	struct location *l;
235 
236 	free(conf.chroot);
237 	free(conf.user);
238 	memset(&conf, 0, sizeof(conf));
239 
240 	for (h = hosts; h->domain != NULL; ++h) {
241 		free((char*)h->domain);
242 		free((char*)h->cert);
243 		free((char*)h->key);
244 		free((char*)h->dir);
245 		free((char*)h->cgi);
246 		free((char*)h->entrypoint);
247 
248 		for (l = h->locations; l->match != NULL; ++l) {
249 			free((char*)l->match);
250 			free((char*)l->lang);
251 			free((char*)l->default_mime);
252 			free((char*)l->index);
253 			free((char*)l->block_fmt);
254 		}
255 	}
256 	memset(hosts, 0, sizeof(hosts));
257 
258 	tls_free(ctx);
259 	tls_config_free(tlsconf);
260 }
261 
262 static void
263 wait_sighup(void)
264 {
265 	sigset_t mask;
266 	int signo;
267 
268 	sigemptyset(&mask);
269 	sigaddset(&mask, SIGHUP);
270 	sigwait(&mask, &signo);
271 }
272 
273 void
274 drop_priv(void)
275 {
276 	struct passwd *pw = NULL;
277 
278 	if (conf.chroot != NULL && conf.user == NULL)
279 		fatal("can't chroot without an user to switch to after.");
280 
281 	if (conf.user != NULL) {
282 		if ((pw = getpwnam(conf.user)) == NULL)
283 			fatal("can't find user %s", conf.user);
284 	}
285 
286 	if (conf.chroot != NULL) {
287 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
288 			fatal("%s: %s", conf.chroot, strerror(errno));
289 	}
290 
291 	if (pw != NULL) {
292 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
293 			fatal("setresuid(%d): %s", pw->pw_uid,
294 			    strerror(errno));
295 	}
296 
297 	if (getuid() == 0)
298 		log_warn(NULL, "not a good idea to run a network daemon as root");
299 }
300 
301 static int
302 spawn_listeners(int *p)
303 {
304 	int i;
305 
306 	close(p[0]);
307 	exfd = p[1];
308 
309 	for (i = 0; i < conf.prefork -1; ++i) {
310 		switch (fork()) {
311 		case -1:
312 			fatal("fork: %s", strerror(errno));
313 		case 0:		/* child */
314 			setproctitle("server(%d)", i+1);
315 			return listener_main();
316 		}
317 	}
318 
319 	if (conf.prefork == 0)
320 		setproctitle("server");
321 	else
322 		setproctitle("server(%d)", conf.prefork);
323 	return listener_main();
324 }
325 
326 static void
327 usage(const char *me)
328 {
329 	fprintf(stderr,
330 	    "USAGE: %s [-fn] [-c config] | [-6h] [-d certs-dir] [-H host]"
331 	    "       [-p port] [-x cgi] [dir]",
332 	    me);
333 }
334 
335 static int
336 serve(int argc, char **argv, int *p)
337 {
338 	char path[PATH_MAX];
339 
340 	if (config_path == NULL) {
341 		if (hostname == NULL)
342 			hostname = "localhost";
343 		if (certs_dir == NULL)
344 			certs_dir = data_dir();
345 		load_local_cert(hostname, certs_dir);
346 
347 		hosts[0].domain = "*";
348 		hosts[0].locations[0].auto_index = 1;
349 		hosts[0].locations[0].match = "*";
350 
351 		switch (argc) {
352 		case 0:
353 			hosts[0].dir = getcwd(path, sizeof(path));
354 			break;
355 		case 1:
356 			hosts[0].dir = absolutify_path(argv[0]);
357 			break;
358 		default:
359 			usage(getprogname());
360 			return 1;
361 		}
362 
363 		log_notice(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
364 	}
365 
366 	/* setup tls before dropping privileges: we don't want user
367 	 * to put private certs inside the chroot. */
368 	setup_tls();
369 
370 	switch (fork()) {
371 	case -1:
372 		fatal("fork: %s", strerror(errno));
373 
374 	case 0:			/* child */
375 		return spawn_listeners(p);
376 
377 	default:		/* parent */
378 		setproctitle("executor");
379 		close(p[1]);
380 		exfd = p[0];
381 		drop_priv();
382 		unblock_signals();
383 		return executor_main();
384 	}
385 }
386 
387 int
388 main(int argc, char **argv)
389 {
390 	int ch, p[2];
391 	int conftest = 0, configless = 0;
392 	int old_ipv6, old_port;
393 
394 	init_config();
395 
396 	while ((ch = getopt(argc, argv, "6c:d:fH:hnp:vx:")) != -1) {
397 		switch (ch) {
398 		case '6':
399 			conf.ipv6 = 1;
400 			configless = 1;
401 			break;
402 
403 		case 'c':
404 			config_path = absolutify_path(optarg);
405 			break;
406 
407 		case 'd':
408 			certs_dir = optarg;
409 			configless = 1;
410 			break;
411 
412 		case 'f':
413 			conf.foreground = 1;
414 			break;
415 
416 		case 'H':
417 			hostname = optarg;
418 			configless = 1;
419 			break;
420 
421 		case 'h':
422 			usage(*argv);
423 			return 0;
424 
425 		case 'n':
426 			conftest = 1;
427 			break;
428 
429 		case 'p':
430 			conf.port = parse_portno(optarg);
431 			configless = 1;
432 			break;
433 
434 		case 'v':
435 			conf.verbose++;
436 			break;
437 
438 		case 'x':
439 			/* drop the starting / (if any) */
440 			if (*optarg == '/')
441 				optarg++;
442 			hosts[0].cgi = optarg;
443 			configless = 1;
444 			break;
445 
446 		default:
447 			usage(*argv);
448 			return 1;
449 		}
450 	}
451 	argc -= optind;
452 	argv += optind;
453 
454 	if (config_path == NULL) {
455 		configless = 1;
456 		conf.foreground = 1;
457 		conf.prefork = 0;
458 		conf.verbose++;
459 	}
460 
461 	if (config_path != NULL && (argc > 0 || configless))
462 		err(1, "can't specify options in config mode.");
463 
464 	if (conftest) {
465 		parse_conf(config_path);
466 		puts("config OK");
467 		return 0;
468 	}
469 
470 	signal(SIGPIPE, SIG_IGN);
471 	signal(SIGCHLD, SIG_IGN);
472 
473 #ifdef SIGINFO
474 	signal(SIGINFO, sig_handler);
475 #endif
476 	signal(SIGUSR2, sig_handler);
477 	signal(SIGHUP, sig_handler);
478 
479 	if (!conf.foreground && !configless) {
480 		if (daemon(1, 1) == -1)
481 			fatal("daemon: %s", strerror(errno));
482 	}
483 
484 	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
485 	    PF_UNSPEC, p) == -1)
486 		fatal("socketpair: %s", strerror(errno));
487 
488 	if (config_path != NULL)
489 		parse_conf(config_path);
490 
491 	sock4 = make_socket(conf.port, AF_INET);
492 	sock6 = -1;
493 	if (conf.ipv6)
494 		sock6 = make_socket(conf.port, AF_INET6);
495 
496 	if (configless)
497 		return serve(argc, argv, p);
498 
499 	/* wait a sighup and reload the daemon */
500 	for (;;) {
501 		block_signals();
502 
503 		hupped = 0;
504 		switch (fork()) {
505 		case -1:
506 			fatal("fork: %s", strerror(errno));
507 		case 0:
508 			return serve(argc, argv, p);
509 		}
510 
511 		close(p[0]);
512 		close(p[1]);
513 
514 		wait_sighup();
515 		unblock_signals();
516 		log_info(NULL, "reloading configuration %s", config_path);
517 
518 		old_ipv6 = conf.ipv6;
519 		old_port = conf.port;
520 
521 		free_config();
522 		init_config();
523 		parse_conf(config_path);
524 
525 		if (old_port != conf.port) {
526 			close(sock4);
527 			close(sock6);
528 			sock4 = -1;
529 			sock6 = -1;
530 		}
531 
532 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
533 			close(sock6);
534 			sock6 = -1;
535 		}
536 
537 		if (sock4 == -1)
538 			sock4 = make_socket(conf.port, AF_INET);
539 		if (sock6 == -1 && conf.ipv6)
540 			sock6 = make_socket(conf.port, AF_INET6);
541 
542 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
543 		    PF_UNSPEC, p) == -1)
544 			fatal("socketpair: %s", strerror(errno));
545 	}
546 }