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