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 <limits.h>
23 #include <netdb.h>
24 #include <pwd.h>
25 #include <signal.h>
26 #include <stdarg.h>
27 #include <string.h>
28 
29 #include <openssl/pem.h>
30 #include <openssl/x509.h>
31 
32 #include "gmid.h"
33 
34 volatile sig_atomic_t hupped;
35 
36 struct vhost hosts[HOSTSLEN];
37 
38 int exfd, foreground, verbose, sock4, sock6;
39 
40 const char *config_path, *certs_dir, *hostname;
41 
42 struct conf conf;
43 
44 struct tls_config *tlsconf;
45 struct tls *ctx;
46 
47 void
48 fatal(const char *fmt, ...)
49 {
50 	va_list ap;
51 
52 	va_start(ap, fmt);
53 
54 	if (foreground) {
55 		vfprintf(stderr, fmt, ap);
56 		fprintf(stderr, "\n");
57 	} else
58 		vsyslog(LOG_DAEMON | LOG_CRIT, fmt, ap);
59 
60 	va_end(ap);
61 	exit(1);
62 }
63 
64 void
65 logs(int priority, struct client *c,
66     const char *fmt, ...)
67 {
68 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
69 	char *fmted, *s;
70 	size_t len;
71 	int ec;
72 	va_list ap;
73 
74 	if (foreground && !verbose) {
75 		if (priority == LOG_DEBUG || priority == LOG_INFO)
76 			return;
77 	}
78 
79 	va_start(ap, fmt);
80 
81 	if (c == NULL) {
82 		strncpy(hbuf, "<internal>", sizeof(hbuf));
83 		sbuf[0] = '\0';
84 	} else {
85 		len = sizeof(c->addr);
86 		ec = getnameinfo((struct sockaddr*)&c->addr, len,
87 		    hbuf, sizeof(hbuf),
88 		    sbuf, sizeof(sbuf),
89 		    NI_NUMERICHOST | NI_NUMERICSERV);
90 		if (ec != 0)
91 			fatal("getnameinfo: %s", gai_strerror(ec));
92 	}
93 
94 	if (vasprintf(&fmted, fmt, ap) == -1)
95 		fatal("vasprintf: %s", strerror(errno));
96 
97 	if (foreground)
98 		fprintf(stderr, "%s:%s %s\n", hbuf, sbuf, fmted);
99 	else {
100 		if (asprintf(&s, "%s:%s %s", hbuf, sbuf, fmted) == -1)
101 			fatal("asprintf: %s", strerror(errno));
102 		syslog(priority | LOG_DAEMON, "%s", s);
103 		free(s);
104 	}
105 
106 	free(fmted);
107 
108 	va_end(ap);
109 }
110 
111 /* strchr, but with a bound */
112 static char *
113 gmid_strnchr(char *s, int c, size_t len)
114 {
115 	size_t i;
116 
117 	for (i = 0; i < len; ++i)
118 		if (s[i] == c)
119 			return &s[i];
120 	return NULL;
121 }
122 
123 void
124 log_request(struct client *c, char *meta, size_t l)
125 {
126 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV], b[GEMINI_URL_LEN];
127 	char *t;
128 	size_t len;
129 	int ec;
130 
131 	len = sizeof(c->addr);
132 	ec = getnameinfo((struct sockaddr*)&c->addr, len,
133 	    hbuf, sizeof(hbuf),
134 	    sbuf, sizeof(sbuf),
135 	    NI_NUMERICHOST | NI_NUMERICSERV);
136 	if (ec != 0)
137 		fatal("getnameinfo: %s", gai_strerror(ec));
138 
139 	if (c->iri.schema != NULL) {
140 		/* serialize the IRI */
141 		strlcpy(b, c->iri.schema, sizeof(b));
142 		strlcat(b, "://", sizeof(b));
143 
144 		/* log the decoded host name, but if it was invalid
145 		 * use the raw one. */
146 		if (*c->domain != '\0')
147 			strlcat(b, c->domain, sizeof(b));
148 		else
149 			strlcat(b, c->iri.host, sizeof(b));
150 
151 		strlcat(b, "/", sizeof(b));
152 		strlcat(b, c->iri.path, sizeof(b)); /* TODO: sanitize UTF8 */
153 		if (*c->iri.query != '\0') {	    /* TODO: sanitize UTF8 */
154 			strlcat(b, "?", sizeof(b));
155 			strlcat(b, c->iri.query, sizeof(b));
156 		}
157 	} else {
158 		strlcpy(b, c->req, sizeof(b));
159 	}
160 
161 	if ((t = gmid_strnchr(meta, '\r', l)) == NULL)
162 		t = meta + len;
163 
164 	if (foreground)
165 		fprintf(stderr, "%s:%s GET %s %.*s\n", hbuf, sbuf, b,
166 		    (int)(t - meta), meta);
167 	else
168 		syslog(LOG_INFO | LOG_DAEMON, "%s:%s GET %s %.*s",
169 		    hbuf, sbuf, b, (int)(t - meta), meta);
170 }
171 
172 void
173 sig_handler(int sig)
174 {
175 	(void)sig;
176 
177 	hupped = sig == SIGHUP;
178 }
179 
180 void
181 gen_certificate(const char *host, const char *certpath, const char *keypath)
182 {
183 	BIGNUM		e;
184 	EVP_PKEY	*pkey;
185 	RSA		*rsa;
186 	X509		*x509;
187 	X509_NAME	*name;
188 	FILE		*f;
189 	const char	*org = "gmid";
190 
191 	LOGN(NULL, "generating new certificate for %s (it could take a while)",
192 	    host);
193 
194 	if ((pkey = EVP_PKEY_new()) == NULL)
195                 fatal("couldn't create a new private key");
196 
197 	if ((rsa = RSA_new()) == NULL)
198 		fatal("could'nt generate rsa");
199 
200 	BN_init(&e);
201 	BN_set_word(&e, 17);
202 	if (!RSA_generate_key_ex(rsa, 4096, &e, NULL))
203 		fatal("couldn't generate a rsa key");
204 
205 	if (!EVP_PKEY_assign_RSA(pkey, rsa))
206 		fatal("couldn't assign the key");
207 
208 	if ((x509 = X509_new()) == NULL)
209 		fatal("couldn't generate the X509 certificate");
210 
211 	ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
212 	X509_gmtime_adj(X509_get_notBefore(x509), 0);
213 	X509_gmtime_adj(X509_get_notAfter(x509), 315360000L); /* 10 years */
214 
215 	if (!X509_set_pubkey(x509, pkey))
216 		fatal("couldn't set the public key");
217 
218 	name = X509_get_subject_name(x509);
219 	if (!X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, org, -1, -1, 0))
220 		fatal("couldn't add N to cert");
221 	if (!X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, host, -1, -1, 0))
222 		fatal("couldn't add CN to cert");
223 	X509_set_issuer_name(x509, name);
224 
225 	if (!X509_sign(x509, pkey, EVP_sha256()))
226                 fatal("couldn't sign the certificate");
227 
228 	if ((f = fopen(keypath, "w")) == NULL)
229 		fatal("fopen(%s): %s", keypath, strerror(errno));
230 	if (!PEM_write_PrivateKey(f, pkey, NULL, NULL, 0, NULL, NULL))
231 		fatal("couldn't write private key");
232 	fclose(f);
233 
234 	if ((f = fopen(certpath, "w")) == NULL)
235 		fatal("fopen(%s): %s", certpath, strerror(errno));
236 	if (!PEM_write_X509(f, x509))
237 		fatal("couldn't write cert");
238 	fclose(f);
239 
240 	X509_free(x509);
241 	RSA_free(rsa);
242 }
243 
244 /* XXX: create recursively */
245 void
246 mkdirs(const char *path)
247 {
248 	if (mkdir(path, 0755) == -1 && errno != EEXIST)
249 		fatal("can't mkdir %s: %s", path, strerror(errno));
250 }
251 
252 /* $XDG_DATA_HOME/gmid */
253 char *
254 data_dir(void)
255 {
256 	const char *home, *xdg;
257 	char *t;
258 
259 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
260 		if ((home = getenv("HOME")) == NULL)
261 			errx(1, "XDG_DATA_HOME and HOME both empty");
262 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
263 			err(1, "asprintf");
264 		mkdirs(t);
265 		return t;
266 	}
267 
268 	if (asprintf(&t, "%s/gmid", xdg) == -1)
269 		err(1, "asprintf");
270 	mkdirs(t);
271 	return t;
272 }
273 
274 void
275 load_local_cert(const char *hostname, const char *dir)
276 {
277 	char *cert, *key;
278 
279 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
280 		errx(1, "asprintf");
281 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
282 		errx(1, "asprintf");
283 
284 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
285 		gen_certificate(hostname, cert, key);
286 
287 	hosts[0].cert = cert;
288 	hosts[0].key = key;
289 	hosts[0].domain = hostname;
290 }
291 
292 void
293 load_vhosts(void)
294 {
295 	struct vhost *h;
296 
297 	for (h = hosts; h->domain != NULL; ++h) {
298 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
299 			fatal("open %s for domain %s", h->dir, h->domain);
300 	}
301 }
302 
303 int
304 make_socket(int port, int family)
305 {
306 	int sock, v;
307 	struct sockaddr_in addr4;
308 	struct sockaddr_in6 addr6;
309 	struct sockaddr *addr;
310 	socklen_t len;
311 
312         switch (family) {
313 	case AF_INET:
314 		bzero(&addr4, sizeof(addr4));
315 		addr4.sin_family = family;
316 		addr4.sin_port = htons(port);
317 		addr4.sin_addr.s_addr = INADDR_ANY;
318 		addr = (struct sockaddr*)&addr4;
319 		len = sizeof(addr4);
320 		break;
321 
322 	case AF_INET6:
323 		bzero(&addr6, sizeof(addr6));
324 		addr6.sin6_family = AF_INET6;
325 		addr6.sin6_port = htons(port);
326 		addr6.sin6_addr = in6addr_any;
327 		addr = (struct sockaddr*)&addr6;
328 		len = sizeof(addr6);
329 		break;
330 
331 	default:
332 		/* unreachable */
333 		abort();
334 	}
335 
336 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
337 		fatal("socket: %s", strerror(errno));
338 
339 	v = 1;
340 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
341 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
342 
343 	v = 1;
344 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
345 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
346 
347 	mark_nonblock(sock);
348 
349 	if (bind(sock, addr, len) == -1)
350 		fatal("bind: %s", strerror(errno));
351 
352 	if (listen(sock, 16) == -1)
353 		fatal("listen: %s", strerror(errno));
354 
355 	return sock;
356 }
357 
358 void
359 setup_tls(void)
360 {
361 	struct vhost *h;
362 
363 	if ((tlsconf = tls_config_new()) == NULL)
364 		fatal("tls_config_new");
365 
366 	/* optionally accept client certs, but don't try to verify them */
367 	tls_config_verify_client_optional(tlsconf);
368 	tls_config_insecure_noverifycert(tlsconf);
369 
370 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
371 		fatal("tls_config_set_protocols");
372 
373 	if ((ctx = tls_server()) == NULL)
374 		fatal("tls_server failure");
375 
376 	/* we need to set something, then we can add how many key we want */
377 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
378 		fatal("tls_config_set_keypair_file failed for (%s, %s)",
379 		    hosts->cert, hosts->key);
380 
381 	for (h = &hosts[1]; h->domain != NULL; ++h) {
382 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
383 			fatal("failed to load the keypair (%s, %s)",
384 			    h->cert, h->key);
385 	}
386 
387 	if (tls_configure(ctx, tlsconf) == -1)
388 		fatal("tls_configure: %s", tls_error(ctx));
389 }
390 
391 static int
392 listener_main(void)
393 {
394 	load_default_mime(&conf.mime);
395 	load_vhosts();
396 	sandbox();
397 	loop(ctx, sock4, sock6);
398 	return 0;
399 }
400 
401 void
402 init_config(void)
403 {
404 	size_t i;
405 
406 	bzero(hosts, sizeof(hosts));
407 	for (i = 0; i < HOSTSLEN; ++i)
408 		hosts[i].dirfd = -1;
409 
410 	conf.port = 1965;
411 	conf.ipv6 = 0;
412 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
413 
414 	init_mime(&conf.mime);
415 
416 	conf.chroot = NULL;
417 	conf.user = NULL;
418 }
419 
420 void
421 free_config(void)
422 {
423 	struct vhost *h;
424 	struct location *l;
425 
426 	free(conf.chroot);
427 	free(conf.user);
428 	memset(&conf, 0, sizeof(conf));
429 
430 	for (h = hosts; h->domain != NULL; ++h) {
431 		free((char*)h->domain);
432 		free((char*)h->cert);
433 		free((char*)h->key);
434 		free((char*)h->dir);
435 		free((char*)h->cgi);
436 
437 		for (l = h->locations; l->match != NULL; ++l) {
438 			free((char*)l->match);
439 			free((char*)l->lang);
440 			free((char*)l->default_mime);
441 			free((char*)l->index);
442 			free((char*)l->block_fmt);
443 		}
444 	}
445 	memset(hosts, 0, sizeof(hosts));
446 
447 	tls_free(ctx);
448 	tls_config_free(tlsconf);
449 }
450 
451 static void
452 wait_sighup(void)
453 {
454 	sigset_t mask;
455 	int signo;
456 
457 	sigemptyset(&mask);
458 	sigaddset(&mask, SIGHUP);
459 	sigwait(&mask, &signo);
460 }
461 
462 void
463 drop_priv(void)
464 {
465 	struct passwd *pw = NULL;
466 
467 	if (conf.chroot != NULL && conf.user == NULL)
468 		fatal("can't chroot without an user to switch to after.");
469 
470 	if (conf.user != NULL) {
471 		if ((pw = getpwnam(conf.user)) == NULL)
472 			fatal("can't find user %s", conf.user);
473 	}
474 
475 	if (conf.chroot != NULL) {
476 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
477 			fatal("%s: %s", conf.chroot, strerror(errno));
478 	}
479 
480 	if (pw != NULL) {
481 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
482 			fatal("setresuid(%d): %s", pw->pw_uid,
483 			    strerror(errno));
484 	}
485 
486 	if (getuid() == 0)
487 		LOGW(NULL, "%s",
488 		    "not a good idea to run a network daemon as root");
489 }
490 
491 void
492 usage(const char *me)
493 {
494 	fprintf(stderr,
495 	    "USAGE: %s [-fn] [-c config] | [-6h] [-d certs-dir] [-H host]"
496 	    "       [-p port] [-x cgi] [dir]",
497 	    me);
498 }
499 
500 static int
501 serve(int argc, char **argv, int *p)
502 {
503 	char path[PATH_MAX];
504 
505 	if (config_path == NULL) {
506 		if (hostname == NULL)
507 			hostname = "localhost";
508 		if (certs_dir == NULL)
509 			certs_dir = data_dir();
510 		load_local_cert(hostname, certs_dir);
511 
512 		hosts[0].domain = "*";
513 		hosts[0].locations[0].auto_index = 1;
514 		hosts[0].locations[0].match = "*";
515 
516 		switch (argc) {
517 		case 0:
518 			hosts[0].dir = getcwd(path, sizeof(path));
519 			break;
520 		case 1:
521 			hosts[0].dir = absolutify_path(argv[0]);
522 			break;
523 		default:
524 			usage(getprogname());
525 			return 1;
526 		}
527 
528 		LOGN(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
529 	}
530 
531 	/* setup tls before dropping privileges: we don't want user
532 	 * to put private certs inside the chroot. */
533 	setup_tls();
534 
535 	switch (fork()) {
536 	case -1:
537 		fatal("fork: %s", strerror(errno));
538 
539 	case 0:			/* child */
540 		setproctitle("listener");
541 		close(p[0]);
542 		exfd = p[1];
543 		drop_priv();
544 		unblock_signals();
545 		listener_main();
546 		_exit(0);
547 
548 	default:		/* parent */
549 		setproctitle("executor");
550 		close(p[1]);
551 		exfd = p[0];
552 		drop_priv();
553 		unblock_signals();
554 		return executor_main();
555 	}
556 }
557 
558 int
559 main(int argc, char **argv)
560 {
561 	int ch, p[2];
562 	int conftest = 0, configless = 0;
563 	int old_ipv6, old_port;
564 
565 	init_config();
566 
567 	while ((ch = getopt(argc, argv, "6c:d:fH:hnp:vx:")) != -1) {
568 		switch (ch) {
569 		case '6':
570 			conf.ipv6 = 1;
571 			configless = 1;
572 			break;
573 
574 		case 'c':
575 			config_path = absolutify_path(optarg);
576 			break;
577 
578 		case 'd':
579 			certs_dir = optarg;
580 			configless = 1;
581 			break;
582 
583 		case 'f':
584 			foreground = 1;
585 			break;
586 
587 		case 'H':
588 			hostname = optarg;
589 			configless = 1;
590 			break;
591 
592 		case 'h':
593 			usage(*argv);
594 			return 0;
595 
596 		case 'n':
597 			conftest = 1;
598 			break;
599 
600 		case 'p':
601 			conf.port = parse_portno(optarg);
602 			configless = 1;
603 			break;
604 
605 		case 'v':
606 			verbose = 1;
607 			break;
608 
609 		case 'x':
610 			/* drop the starting / (if any) */
611 			if (*optarg == '/')
612 				optarg++;
613 			hosts[0].cgi = optarg;
614 			configless = 1;
615 			break;
616 
617 		default:
618 			usage(*argv);
619 			return 1;
620 		}
621 	}
622 	argc -= optind;
623 	argv += optind;
624 
625 	if (config_path == NULL) {
626 		configless = 1;
627 		foreground = 1;
628 	}
629 
630 	if (config_path != NULL && (argc > 0 || configless))
631 		err(1, "can't specify options in config mode.");
632 
633 	if (conftest) {
634 		parse_conf(config_path);
635 		puts("config OK");
636 		return 0;
637 	}
638 
639 	signal(SIGPIPE, SIG_IGN);
640 	signal(SIGCHLD, SIG_IGN);
641 
642 #ifdef SIGINFO
643 	signal(SIGINFO, sig_handler);
644 #endif
645 	signal(SIGUSR2, sig_handler);
646 	signal(SIGHUP, sig_handler);
647 
648 	if (!foreground && !configless) {
649 		if (daemon(1, 1) == -1)
650 			fatal("daemon: %s", strerror(errno));
651 	}
652 
653 	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
654 	    PF_UNSPEC, p) == -1)
655 		fatal("socketpair: %s", strerror(errno));
656 
657 	if (config_path != NULL)
658 		parse_conf(config_path);
659 
660 	sock4 = make_socket(conf.port, AF_INET);
661 	sock6 = -1;
662 	if (conf.ipv6)
663 		sock6 = make_socket(conf.port, AF_INET6);
664 
665 	if (configless)
666 		return serve(argc, argv, p);
667 
668 	/* wait a sighup and reload the daemon */
669 	for (;;) {
670 		block_signals();
671 
672 		hupped = 0;
673 		switch (fork()) {
674 		case -1:
675 			fatal("fork: %s", strerror(errno));
676 		case 0:
677 			return serve(argc, argv, p);
678 		}
679 
680 		close(p[0]);
681 		close(p[1]);
682 
683 		wait_sighup();
684 		unblock_signals();
685 		LOGI(NULL, "reloading configuration %s", config_path);
686 
687 		old_ipv6 = conf.ipv6;
688 		old_port = conf.port;
689 
690 		free_config();
691 		init_config();
692 		parse_conf(config_path);
693 
694 		if (old_port != conf.port) {
695 			close(sock4);
696 			close(sock6);
697 			sock4 = -1;
698 			sock6 = -1;
699 		}
700 
701 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
702 			close(sock6);
703 			sock6 = -1;
704 		}
705 
706 		if (sock4 == -1)
707 			sock4 = make_socket(conf.port, AF_INET);
708 		if (sock6 == -1 && conf.ipv6)
709 			sock6 = make_socket(conf.port, AF_INET6);
710 
711 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
712 		    PF_UNSPEC, p) == -1)
713 			fatal("socketpair: %s", strerror(errno));
714 	}
715 }