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 <errno.h>
18 #include <fcntl.h>
19 #include <limits.h>
20 #include <netdb.h>
21 #include <pwd.h>
22 #include <signal.h>
23 #include <stdarg.h>
24 #include <string.h>
25 
26 #include "gmid.h"
27 
28 struct vhost hosts[HOSTSLEN];
29 
30 int goterror;
31 
32 int exfd;
33 
34 struct conf conf;
35 
36 struct tls *ctx;
37 
38 void
39 fatal(const char *fmt, ...)
40 {
41 	va_list ap;
42 
43 	va_start(ap, fmt);
44 
45 	if (conf.foreground) {
46 		vfprintf(stderr, fmt, ap);
47 		fprintf(stderr, "\n");
48 	} else
49 		vsyslog(LOG_DAEMON | LOG_CRIT, fmt, ap);
50 
51 	va_end(ap);
52 	exit(1);
53 }
54 
55 void
56 logs(int priority, struct client *c,
57     const char *fmt, ...)
58 {
59 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
60 	char *fmted, *s;
61 	size_t len;
62 	int ec;
63 	va_list ap;
64 
65 	va_start(ap, fmt);
66 
67 	if (c == NULL) {
68 		strncpy(hbuf, "<internal>", sizeof(hbuf));
69 		sbuf[0] = '\0';
70 	} else {
71 		len = sizeof(c->addr);
72 		ec = getnameinfo((struct sockaddr*)&c->addr, len,
73 		    hbuf, sizeof(hbuf),
74 		    sbuf, sizeof(sbuf),
75 		    NI_NUMERICHOST | NI_NUMERICSERV);
76 		if (ec != 0)
77 			fatal("getnameinfo: %s", gai_strerror(ec));
78 	}
79 
80 	if (vasprintf(&fmted, fmt, ap) == -1)
81 		fatal("vasprintf: %s", strerror(errno));
82 
83 	if (conf.foreground)
84 		fprintf(stderr, "%s:%s %s\n", hbuf, sbuf, fmted);
85 	else {
86 		if (asprintf(&s, "%s:%s %s", hbuf, sbuf, fmted) == -1)
87 			fatal("asprintf: %s", strerror(errno));
88 		syslog(priority | LOG_DAEMON, "%s", s);
89 		free(s);
90 	}
91 
92 	free(fmted);
93 
94 	va_end(ap);
95 }
96 
97 /* strchr, but with a bound */
98 static char *
99 gmid_strnchr(char *s, int c, size_t len)
100 {
101 	size_t i;
102 
103 	for (i = 0; i < len; ++i)
104 		if (s[i] == c)
105 			return &s[i];
106 	return NULL;
107 }
108 
109 void
110 log_request(struct client *c, char *meta, size_t l)
111 {
112 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV], b[GEMINI_URL_LEN];
113 	char *t;
114 	size_t len;
115 	int ec;
116 
117 	len = sizeof(c->addr);
118 	ec = getnameinfo((struct sockaddr*)&c->addr, len,
119 	    hbuf, sizeof(hbuf),
120 	    sbuf, sizeof(sbuf),
121 	    NI_NUMERICHOST | NI_NUMERICSERV);
122 	if (ec != 0)
123 		fatal("getnameinfo: %s", gai_strerror(ec));
124 
125 	if (c->iri.schema != NULL) {
126 		/* serialize the IRI */
127 		strlcpy(b, c->iri.schema, sizeof(b));
128 		strlcat(b, "://", sizeof(b));
129 		strlcat(b, c->iri.host, sizeof(b));
130 		strlcat(b, "/", sizeof(b));
131 		strlcat(b, c->iri.path, sizeof(b)); /* TODO: sanitize UTF8 */
132 		if (*c->iri.query != '\0') {	    /* TODO: sanitize UTF8 */
133 			strlcat(b, "?", sizeof(b));
134 			strlcat(b, c->iri.query, sizeof(b));
135 		}
136 	} else {
137 		strlcpy(b, c->req, sizeof(b));
138 	}
139 
140 	if ((t = gmid_strnchr(meta, '\r', l)) == NULL)
141 		t = meta + len;
142 
143 	if (conf.foreground)
144 		fprintf(stderr, "%s:%s GET %s %.*s\n", hbuf, sbuf, b,
145 		    (int)(t - meta), meta);
146 	else
147 		syslog(LOG_INFO | LOG_DAEMON, "%s:%s GET %s %.*s",
148 		    hbuf, sbuf, b, (int)(t - meta), meta);
149 }
150 
151 void
152 sig_handler(int sig)
153 {
154 	(void)sig;
155 }
156 
157 int
158 starts_with(const char *str, const char *prefix)
159 {
160 	size_t i;
161 
162 	if (prefix == NULL)
163 		return 0;
164 
165 	for (i = 0; prefix[i] != '\0'; ++i)
166 		if (str[i] != prefix[i])
167 			return 0;
168 	return 1;
169 }
170 
171 int
172 ends_with(const char *str, const char *sufx)
173 {
174 	size_t i, j;
175 
176 	i = strlen(str);
177 	j = strlen(sufx);
178 
179 	if (j > i)
180 		return 0;
181 
182 	i -= j;
183 	for (j = 0; str[i] != '\0'; i++, j++)
184 		if (str[i] != sufx[j])
185 			return 0;
186 	return 1;
187 }
188 
189 ssize_t
190 filesize(int fd)
191 {
192 	ssize_t len;
193 
194 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
195 		return -1;
196 	if (lseek(fd, 0, SEEK_SET) == -1)
197 		return -1;
198 	return len;
199 }
200 
201 char *
202 absolutify_path(const char *path)
203 {
204 	char *wd, *r;
205 
206 	if (*path == '/')
207 		return strdup(path);
208 
209 	wd = getcwd(NULL, 0);
210 	if (asprintf(&r, "%s/%s", wd, path) == -1)
211 		fatal("asprintf: %s", strerror(errno));
212 	free(wd);
213 	return r;
214 }
215 
216 void
217 yyerror(const char *msg)
218 {
219 	goterror = 1;
220 	fprintf(stderr, "%d: %s\n", yylineno, msg);
221 }
222 
223 int
224 parse_portno(const char *p)
225 {
226 	const char *errstr;
227 	int n;
228 
229 	n = strtonum(p, 0, UINT16_MAX, &errstr);
230 	if (errstr != NULL)
231 		errx(1, "port number is %s: %s", errstr, p);
232 	return n;
233 }
234 
235 void
236 parse_conf(const char *path)
237 {
238 	if ((yyin = fopen(path, "r")) == NULL)
239 		fatal("cannot open config %s", path);
240 	yyparse();
241 	fclose(yyin);
242 
243 	if (goterror)
244 		exit(1);
245 }
246 
247 void
248 load_vhosts(void)
249 {
250 	struct vhost *h;
251 
252 	for (h = hosts; h->domain != NULL; ++h) {
253 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
254 			fatal("open %s for domain %s", h->dir, h->domain);
255 	}
256 }
257 
258 int
259 make_socket(int port, int family)
260 {
261 	int sock, v;
262 	struct sockaddr_in addr4;
263 	struct sockaddr_in6 addr6;
264 	struct sockaddr *addr;
265 	socklen_t len;
266 
267         switch (family) {
268 	case AF_INET:
269 		bzero(&addr4, sizeof(addr4));
270 		addr4.sin_family = family;
271 		addr4.sin_port = htons(port);
272 		addr4.sin_addr.s_addr = INADDR_ANY;
273 		addr = (struct sockaddr*)&addr4;
274 		len = sizeof(addr4);
275 		break;
276 
277 	case AF_INET6:
278 		bzero(&addr6, sizeof(addr6));
279 		addr6.sin6_family = AF_INET6;
280 		addr6.sin6_port = htons(port);
281 		addr6.sin6_addr = in6addr_any;
282 		addr = (struct sockaddr*)&addr6;
283 		len = sizeof(addr6);
284 		break;
285 
286 	default:
287 		/* unreachable */
288 		abort();
289 	}
290 
291 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
292 		fatal("socket: %s", strerror(errno));
293 
294 	v = 1;
295 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
296 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
297 
298 	v = 1;
299 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
300 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
301 
302 	mark_nonblock(sock);
303 
304 	if (bind(sock, addr, len) == -1)
305 		fatal("bind: %s", strerror(errno));
306 
307 	if (listen(sock, 16) == -1)
308 		fatal("listen: %s", strerror(errno));
309 
310 	return sock;
311 }
312 
313 void
314 setup_tls(void)
315 {
316 	struct tls_config *tlsconf;
317 	struct vhost *h;
318 
319 	if ((tlsconf = tls_config_new()) == NULL)
320 		fatal("tls_config_new");
321 
322 	/* optionally accept client certs, but don't try to verify them */
323 	tls_config_verify_client_optional(tlsconf);
324 	tls_config_insecure_noverifycert(tlsconf);
325 
326 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
327 		fatal("tls_config_set_protocols");
328 
329 	if ((ctx = tls_server()) == NULL)
330 		fatal("tls_server failure");
331 
332 	/* we need to set something, then we can add how many key we want */
333 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
334 		fatal("tls_config_set_keypair_file failed");
335 
336 	for (h = hosts; h->domain != NULL; ++h) {
337 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
338 			fatal("failed to load the keypair (%s, %s)",
339 			    h->cert, h->key);
340 	}
341 
342 	if (tls_configure(ctx, tlsconf) == -1)
343 		fatal("tls_configure: %s", tls_error(ctx));
344 }
345 
346 int
347 listener_main(void)
348 {
349 	int sock4, sock6;
350 
351 	load_default_mime(&conf.mime);
352 
353 	if (!conf.foreground && daemon(0, 1) == -1)
354 		exit(1);
355 
356 	sock4 = make_socket(conf.port, AF_INET);
357 	sock6 = -1;
358 	if (conf.ipv6)
359 		sock6 = make_socket(conf.port, AF_INET6);
360 
361 	load_vhosts();
362 
363 	sandbox();
364 	loop(ctx, sock4, sock6);
365 
366 	return 0;
367 }
368 
369 void
370 init_config(void)
371 {
372 	size_t i;
373 
374 	bzero(hosts, sizeof(hosts));
375 	for (i = 0; i < HOSTSLEN; ++i)
376 		hosts[i].dirfd = -1;
377 
378 	conf.foreground = 1;
379 	conf.port = 1965;
380 	conf.ipv6 = 0;
381 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
382 
383 	init_mime(&conf.mime);
384 
385 	conf.chroot = NULL;
386 	conf.user = NULL;
387 }
388 
389 void
390 drop_priv(void)
391 {
392 	struct passwd *pw = NULL;
393 
394 	if (conf.chroot != NULL && conf.user == NULL)
395 		fatal("can't chroot without an user to switch to after.");
396 
397 	if (conf.user != NULL) {
398 		if ((pw = getpwnam(conf.user)) == NULL)
399 			fatal("can't find user %s", conf.user);
400 	}
401 
402 	if (conf.chroot != NULL) {
403 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
404 			fatal("%s: %s", conf.chroot, strerror(errno));
405 	}
406 
407 	if (pw != NULL) {
408 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
409 			fatal("setresuid(%d): %s", pw->pw_uid,
410 			    strerror(errno));
411 	}
412 
413 	if (getuid() == 0)
414 		LOGW(NULL, "%s",
415 		    "not a good idea to run a network daemon as root");
416 }
417 
418 void
419 usage(const char *me)
420 {
421 	fprintf(stderr,
422 	    "USAGE: %s [-n] [-c config] | [-6fh] [-C cert] [-d root] [-K key] "
423 	    "[-p port] [-x cgi-bin]\n",
424 	    me);
425 }
426 
427 int
428 main(int argc, char **argv)
429 {
430 	int ch, p[2];
431 	const char *config_path = NULL;
432 	int conftest = 0;
433 
434 	init_config();
435 
436 	while ((ch = getopt(argc, argv, "6C:c:d:fhK:np:x:")) != -1) {
437 		switch (ch) {
438 		case '6':
439 			conf.ipv6 = 1;
440 			break;
441 
442 		case 'C':
443 			hosts[0].cert = optarg;
444 			break;
445 
446 		case 'c':
447 			config_path = optarg;
448 			break;
449 
450 		case 'd':
451 			free((char*)hosts[0].dir);
452 			if ((hosts[0].dir = absolutify_path(optarg)) == NULL)
453 				fatal("absolutify_path");
454 			break;
455 
456 		case 'f':
457 			conf.foreground = 1;
458 			break;
459 
460 		case 'h':
461 			usage(*argv);
462 			return 0;
463 
464 		case 'K':
465 			hosts[0].key = optarg;
466 			break;
467 
468 		case 'n':
469 			conftest = 1;
470 			break;
471 
472 		case 'p':
473 			conf.port = parse_portno(optarg);
474 			break;
475 
476 		case 'x':
477 			/* drop the starting / (if any) */
478 			if (*optarg == '/')
479 				optarg++;
480 			hosts[0].cgi = optarg;
481 			break;
482 
483 		default:
484 			usage(*argv);
485 			return 1;
486 		}
487 	}
488 
489 	if (config_path != NULL) {
490 		if (hosts[0].cert != NULL || hosts[0].key != NULL ||
491 		    hosts[0].dir != NULL)
492 			fatal("can't specify options in conf mode");
493 		parse_conf(config_path);
494 	} else {
495 		if (hosts[0].cert == NULL || hosts[0].key == NULL ||
496 		    hosts[0].dir == NULL)
497 			fatal("missing cert, key or root directory to serve");
498 		hosts[0].domain = "*";
499 	}
500 
501 	if (conftest) {
502 		puts("config OK");
503 		return 0;
504 	}
505 
506 	/* setup tls before dropping privileges: we don't want user
507 	 * to put private certs inside the chroot. */
508 	setup_tls();
509 	drop_priv();
510 
511 	signal(SIGPIPE, SIG_IGN);
512 	signal(SIGCHLD, SIG_IGN);
513 
514 #ifdef SIGINFO
515 	signal(SIGINFO, sig_handler);
516 #endif
517 	signal(SIGUSR2, sig_handler);
518 
519 	if (!conf.foreground) {
520 		signal(SIGHUP, SIG_IGN);
521 		if (daemon(1, 1) == -1)
522 			fatal("daemon: %s", strerror(errno));
523 	}
524 
525 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
526 		fatal("socketpair: %s", strerror(errno));
527 
528 	switch (fork()) {
529 	case -1:
530 		fatal("fork: %s", strerror(errno));
531 
532 	case 0:			/* child */
533 		close(p[0]);
534 		exfd = p[1];
535 		listener_main();
536 		_exit(0);
537 
538 	default:		/* parent */
539 		close(p[1]);
540 		return executor_main(p[0]);
541 	}
542 }