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, servpipes[PROC_MAX];
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 void
303 usage(const char *me)
304 {
305 	fprintf(stderr,
306 	    "USAGE: %s [-fn] [-c config] | [-6h] [-d certs-dir] [-H host]"
307 	    "       [-p port] [-x cgi] [dir]\n",
308 	    me);
309 }
310 
311 static void
312 logger_init(void)
313 {
314 	int p[2];
315 
316 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
317 		err(1, "socketpair");
318 
319 	switch (fork()) {
320 	case -1:
321 		err(1, "fork");
322 	case 0:
323 		logfd = p[1];
324 		close(p[0]);
325 		setproctitle("logger");
326 		imsg_init(&logcibuf, p[1]);
327 		drop_priv();
328 		_exit(logger_main(p[1], &logcibuf));
329 	default:
330 		logfd = p[0];
331 		close(p[1]);
332 		imsg_init(&logpibuf, p[0]);
333 		return;
334 	}
335 }
336 
337 static int
338 serve(int argc, char **argv)
339 {
340 	char	path[PATH_MAX];
341 	int	i, p[2];
342 
343         if (config_path == NULL) {
344 		if (hostname == NULL)
345 			hostname = "localhost";
346 		if (certs_dir == NULL)
347 			certs_dir = data_dir();
348 		load_local_cert(hostname, certs_dir);
349 
350 		hosts[0].domain = "*";
351 		hosts[0].locations[0].auto_index = 1;
352 		hosts[0].locations[0].match = "*";
353 
354 		switch (argc) {
355 		case 0:
356 			hosts[0].dir = getcwd(path, sizeof(path));
357 			break;
358 		case 1:
359 			hosts[0].dir = absolutify_path(argv[0]);
360 			break;
361 		default:
362 			usage(getprogname());
363 			return 1;
364 		}
365 
366 		log_notice(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
367 	}
368 
369 	/* setup tls before dropping privileges: we don't want user
370 	 * to put private certs inside the chroot. */
371 	setup_tls();
372 
373 	for (i = 0; i < conf.prefork; ++i) {
374 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
375 		    PF_UNSPEC, p) == -1)
376 			fatal("socketpair: %s", strerror(errno));
377 
378 		switch (fork()) {
379 		case -1:
380 			fatal("fork: %s", strerror(errno));
381 		case 0:		/* child */
382 			close(p[0]);
383 			exfd = p[1];
384 			setproctitle("server");
385 			_exit(listener_main());
386 		default:
387 			servpipes[i] = p[0];
388 			close(p[1]);
389 		}
390 	}
391 
392 	setproctitle("executor");
393 	drop_priv();
394 	unblock_signals();
395 	_exit(executor_main());
396 }
397 
398 int
399 main(int argc, char **argv)
400 {
401 	int ch, conftest = 0, configless = 0;
402 	int old_ipv6, old_port;
403 
404 	init_config();
405 
406 	while ((ch = getopt(argc, argv, "6c:d:fH:hnp:vx:")) != -1) {
407 		switch (ch) {
408 		case '6':
409 			conf.ipv6 = 1;
410 			configless = 1;
411 			break;
412 
413 		case 'c':
414 			config_path = absolutify_path(optarg);
415 			break;
416 
417 		case 'd':
418 			certs_dir = optarg;
419 			configless = 1;
420 			break;
421 
422 		case 'f':
423 			conf.foreground = 1;
424 			break;
425 
426 		case 'H':
427 			hostname = optarg;
428 			configless = 1;
429 			break;
430 
431 		case 'h':
432 			usage(*argv);
433 			return 0;
434 
435 		case 'n':
436 			conftest = 1;
437 			break;
438 
439 		case 'p':
440 			conf.port = parse_portno(optarg);
441 			configless = 1;
442 			break;
443 
444 		case 'v':
445 			conf.verbose++;
446 			break;
447 
448 		case 'x':
449 			/* drop the starting / (if any) */
450 			if (*optarg == '/')
451 				optarg++;
452 			hosts[0].cgi = optarg;
453 			configless = 1;
454 			break;
455 
456 		default:
457 			usage(*argv);
458 			return 1;
459 		}
460 	}
461 	argc -= optind;
462 	argv += optind;
463 
464 	if (config_path == NULL) {
465 		configless = 1;
466 		conf.foreground = 1;
467 		conf.prefork = 1;
468 		conf.verbose++;
469 	}
470 
471 	if (config_path != NULL && (argc > 0 || configless))
472 		err(1, "can't specify options in config mode.");
473 
474 	if (conftest) {
475 		parse_conf(config_path);
476 		puts("config OK");
477 		return 0;
478 	}
479 
480 	signal(SIGPIPE, SIG_IGN);
481 	signal(SIGCHLD, SIG_IGN);
482 
483 #ifdef SIGINFO
484 	signal(SIGINFO, sig_handler);
485 #endif
486 	signal(SIGUSR2, sig_handler);
487 	signal(SIGHUP, sig_handler);
488 
489 	if (!conf.foreground && !configless) {
490 		if (daemon(1, 1) == -1)
491 			err(1, "daemon");
492 	}
493 
494 	if (config_path != NULL)
495 		parse_conf(config_path);
496 
497 	logger_init();
498 
499 	sock4 = make_socket(conf.port, AF_INET);
500 	sock6 = -1;
501 	if (conf.ipv6)
502 		sock6 = make_socket(conf.port, AF_INET6);
503 
504 	if (configless)
505 		return serve(argc, argv);
506 
507 	/* wait a sighup and reload the daemon */
508 	for (;;) {
509 		block_signals();
510 
511 		hupped = 0;
512 		switch (fork()) {
513 		case -1:
514 			fatal("fork: %s", strerror(errno));
515 		case 0:
516 			return serve(argc, argv);
517 		}
518 
519 		wait_sighup();
520 		unblock_signals();
521 		log_info(NULL, "reloading configuration %s", config_path);
522 
523 		old_ipv6 = conf.ipv6;
524 		old_port = conf.port;
525 
526 		free_config();
527 		init_config();
528 		parse_conf(config_path);
529 
530 		if (old_port != conf.port) {
531 			close(sock4);
532 			close(sock6);
533 			sock4 = -1;
534 			sock6 = -1;
535 		}
536 
537 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
538 			close(sock6);
539 			sock6 = -1;
540 		}
541 
542 		if (sock4 == -1)
543 			sock4 = make_socket(conf.port, AF_INET);
544 		if (sock6 == -1 && conf.ipv6)
545 			sock6 = make_socket(conf.port, AF_INET6);
546 	}
547 }