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Date:: Mon Jan 25 14:08:31 2021 UTC
Message:: rework the configless mode: change flags and generate certs
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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 <netdb.h>
23 #include <pwd.h>
24 #include <signal.h>
25 #include <stdarg.h>
26 #include <string.h>
27 
28 #include <openssl/pem.h>
29 #include <openssl/x509.h>
30 
31 #include "gmid.h"
32 
33 struct vhost hosts[HOSTSLEN];
34 
35 int goterror;
36 
37 int exfd;
38 
39 struct conf conf;
40 
41 struct tls *ctx;
42 
43 void
44 fatal(const char *fmt, ...)
45 {
46 	va_list ap;
47 
48 	va_start(ap, fmt);
49 
50 	if (conf.foreground) {
51 		vfprintf(stderr, fmt, ap);
52 		fprintf(stderr, "\n");
53 	} else
54 		vsyslog(LOG_DAEMON | LOG_CRIT, fmt, ap);
55 
56 	va_end(ap);
57 	exit(1);
58 }
59 
60 void
61 logs(int priority, struct client *c,
62     const char *fmt, ...)
63 {
64 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
65 	char *fmted, *s;
66 	size_t len;
67 	int ec;
68 	va_list ap;
69 
70 	va_start(ap, fmt);
71 
72 	if (c == NULL) {
73 		strncpy(hbuf, "<internal>", sizeof(hbuf));
74 		sbuf[0] = '\0';
75 	} else {
76 		len = sizeof(c->addr);
77 		ec = getnameinfo((struct sockaddr*)&c->addr, len,
78 		    hbuf, sizeof(hbuf),
79 		    sbuf, sizeof(sbuf),
80 		    NI_NUMERICHOST | NI_NUMERICSERV);
81 		if (ec != 0)
82 			fatal("getnameinfo: %s", gai_strerror(ec));
83 	}
84 
85 	if (vasprintf(&fmted, fmt, ap) == -1)
86 		fatal("vasprintf: %s", strerror(errno));
87 
88 	if (conf.foreground)
89 		fprintf(stderr, "%s:%s %s\n", hbuf, sbuf, fmted);
90 	else {
91 		if (asprintf(&s, "%s:%s %s", hbuf, sbuf, fmted) == -1)
92 			fatal("asprintf: %s", strerror(errno));
93 		syslog(priority | LOG_DAEMON, "%s", s);
94 		free(s);
95 	}
96 
97 	free(fmted);
98 
99 	va_end(ap);
100 }
101 
102 /* strchr, but with a bound */
103 static char *
104 gmid_strnchr(char *s, int c, size_t len)
105 {
106 	size_t i;
107 
108 	for (i = 0; i < len; ++i)
109 		if (s[i] == c)
110 			return &s[i];
111 	return NULL;
112 }
113 
114 void
115 log_request(struct client *c, char *meta, size_t l)
116 {
117 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV], b[GEMINI_URL_LEN];
118 	char *t;
119 	size_t len;
120 	int ec;
121 
122 	len = sizeof(c->addr);
123 	ec = getnameinfo((struct sockaddr*)&c->addr, len,
124 	    hbuf, sizeof(hbuf),
125 	    sbuf, sizeof(sbuf),
126 	    NI_NUMERICHOST | NI_NUMERICSERV);
127 	if (ec != 0)
128 		fatal("getnameinfo: %s", gai_strerror(ec));
129 
130 	if (c->iri.schema != NULL) {
131 		/* serialize the IRI */
132 		strlcpy(b, c->iri.schema, sizeof(b));
133 		strlcat(b, "://", sizeof(b));
134 		strlcat(b, c->iri.host, sizeof(b));
135 		strlcat(b, "/", sizeof(b));
136 		strlcat(b, c->iri.path, sizeof(b)); /* TODO: sanitize UTF8 */
137 		if (*c->iri.query != '\0') {	    /* TODO: sanitize UTF8 */
138 			strlcat(b, "?", sizeof(b));
139 			strlcat(b, c->iri.query, sizeof(b));
140 		}
141 	} else {
142 		strlcpy(b, c->req, sizeof(b));
143 	}
144 
145 	if ((t = gmid_strnchr(meta, '\r', l)) == NULL)
146 		t = meta + len;
147 
148 	if (conf.foreground)
149 		fprintf(stderr, "%s:%s GET %s %.*s\n", hbuf, sbuf, b,
150 		    (int)(t - meta), meta);
151 	else
152 		syslog(LOG_INFO | LOG_DAEMON, "%s:%s GET %s %.*s",
153 		    hbuf, sbuf, b, (int)(t - meta), meta);
154 }
155 
156 void
157 sig_handler(int sig)
158 {
159 	(void)sig;
160 }
161 
162 int
163 starts_with(const char *str, const char *prefix)
164 {
165 	size_t i;
166 
167 	if (prefix == NULL)
168 		return 0;
169 
170 	for (i = 0; prefix[i] != '\0'; ++i)
171 		if (str[i] != prefix[i])
172 			return 0;
173 	return 1;
174 }
175 
176 int
177 ends_with(const char *str, const char *sufx)
178 {
179 	size_t i, j;
180 
181 	i = strlen(str);
182 	j = strlen(sufx);
183 
184 	if (j > i)
185 		return 0;
186 
187 	i -= j;
188 	for (j = 0; str[i] != '\0'; i++, j++)
189 		if (str[i] != sufx[j])
190 			return 0;
191 	return 1;
192 }
193 
194 ssize_t
195 filesize(int fd)
196 {
197 	ssize_t len;
198 
199 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
200 		return -1;
201 	if (lseek(fd, 0, SEEK_SET) == -1)
202 		return -1;
203 	return len;
204 }
205 
206 char *
207 absolutify_path(const char *path)
208 {
209 	char *wd, *r;
210 
211 	if (*path == '/')
212 		return strdup(path);
213 
214 	wd = getcwd(NULL, 0);
215 	if (asprintf(&r, "%s/%s", wd, path) == -1)
216 		fatal("asprintf: %s", strerror(errno));
217 	free(wd);
218 	return r;
219 }
220 
221 void
222 gen_certificate(const char *host, const char *certpath, const char *keypath)
223 {
224 	BIGNUM		e;
225 	EVP_PKEY	*pkey;
226 	RSA		*rsa;
227 	X509		*x509;
228 	X509_NAME	*name;
229 	FILE		*f;
230 	const char	*org = "gmid";
231 
232 	LOGN(NULL, "generating a new certificate for %s in %s (it could take a while)",
233 	    host, certpath);
234 
235 	if ((pkey = EVP_PKEY_new()) == NULL)
236                 fatal("couldn't create a new private key");
237 
238 	if ((rsa = RSA_new()) == NULL)
239 		fatal("could'nt generate rsa");
240 
241 	BN_init(&e);
242 	BN_set_word(&e, 17);
243 	if (!RSA_generate_key_ex(rsa, 4096, &e, NULL))
244 		fatal("couldn't generate a rsa key");
245 
246 	if (!EVP_PKEY_assign_RSA(pkey, rsa))
247 		fatal("couldn't assign the key");
248 
249 	if ((x509 = X509_new()) == NULL)
250 		fatal("couldn't generate the X509 certificate");
251 
252 	ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
253 	X509_gmtime_adj(X509_get_notBefore(x509), 0);
254 	X509_gmtime_adj(X509_get_notAfter(x509), 315360000L); /* 10 years */
255 
256 	if (!X509_set_pubkey(x509, pkey))
257 		fatal("couldn't set the public key");
258 
259 	name = X509_get_subject_name(x509);
260 	if (!X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, org, -1, -1, 0))
261 		fatal("couldn't add N to cert");
262 	if (!X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, host, -1, -1, 0))
263 		fatal("couldn't add CN to cert");
264 	X509_set_issuer_name(x509, name);
265 
266 	if (!X509_sign(x509, pkey, EVP_sha256()))
267                 fatal("couldn't sign the certificate");
268 
269 	if ((f = fopen(keypath, "w")) == NULL)
270 		fatal("fopen(%s): %s", keypath, strerror(errno));
271 	if (!PEM_write_PrivateKey(f, pkey, NULL, NULL, 0, NULL, NULL))
272 		fatal("couldn't write private key");
273 	fclose(f);
274 
275 	if ((f = fopen(certpath, "w")) == NULL)
276 		fatal("fopen(%s): %s", certpath, strerror(errno));
277 	if (!PEM_write_X509(f, x509))
278 		fatal("couldn't write cert");
279 	fclose(f);
280 
281 	X509_free(x509);
282 	RSA_free(rsa);
283 }
284 
285 /* XXX: create recursively */
286 void
287 mkdirs(const char *path)
288 {
289 	if (mkdir(path, 0755) == -1 && errno != EEXIST)
290 		fatal("can't mkdir %s: %s", path, strerror(errno));
291 }
292 
293 /* $XDG_DATA_HOME/gmid */
294 char *
295 data_dir(void)
296 {
297 	const char *home, *xdg;
298 	char dir[PATH_MAX];
299 	char *t;
300 
301 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
302 		if ((home = getenv("HOME")) == NULL)
303 			errx(1, "XDG_DATA_HOME and HOME both empty");
304 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
305 			err(1, "asprintf");
306 		mkdirs(t);
307 		return t;
308 	}
309 
310 	if (asprintf(&t, "%s/gmid", xdg) == -1)
311 		err(1, "asprintf");
312 	mkdirs(t);
313 	return t;
314 }
315 
316 void
317 load_local_cert(const char *hostname, const char *dir)
318 {
319 	char *cert, *key;
320 
321 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
322 		errx(1, "asprintf");
323 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
324 		errx(1, "asprintf");
325 
326 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
327 		gen_certificate(hostname, cert, key);
328 
329 	hosts[0].cert = cert;
330 	hosts[0].key = key;
331 	hosts[0].domain = hostname;
332 }
333 
334 void
335 yyerror(const char *msg)
336 {
337 	goterror = 1;
338 	fprintf(stderr, "%d: %s\n", yylineno, msg);
339 }
340 
341 int
342 parse_portno(const char *p)
343 {
344 	const char *errstr;
345 	int n;
346 
347 	n = strtonum(p, 0, UINT16_MAX, &errstr);
348 	if (errstr != NULL)
349 		errx(1, "port number is %s: %s", errstr, p);
350 	return n;
351 }
352 
353 void
354 parse_conf(const char *path)
355 {
356 	if ((yyin = fopen(path, "r")) == NULL)
357 		fatal("cannot open config %s", path);
358 	yyparse();
359 	fclose(yyin);
360 
361 	if (goterror)
362 		exit(1);
363 }
364 
365 void
366 load_vhosts(void)
367 {
368 	struct vhost *h;
369 
370 	for (h = hosts; h->domain != NULL; ++h) {
371 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
372 			fatal("open %s for domain %s", h->dir, h->domain);
373 	}
374 }
375 
376 int
377 make_socket(int port, int family)
378 {
379 	int sock, v;
380 	struct sockaddr_in addr4;
381 	struct sockaddr_in6 addr6;
382 	struct sockaddr *addr;
383 	socklen_t len;
384 
385         switch (family) {
386 	case AF_INET:
387 		bzero(&addr4, sizeof(addr4));
388 		addr4.sin_family = family;
389 		addr4.sin_port = htons(port);
390 		addr4.sin_addr.s_addr = INADDR_ANY;
391 		addr = (struct sockaddr*)&addr4;
392 		len = sizeof(addr4);
393 		break;
394 
395 	case AF_INET6:
396 		bzero(&addr6, sizeof(addr6));
397 		addr6.sin6_family = AF_INET6;
398 		addr6.sin6_port = htons(port);
399 		addr6.sin6_addr = in6addr_any;
400 		addr = (struct sockaddr*)&addr6;
401 		len = sizeof(addr6);
402 		break;
403 
404 	default:
405 		/* unreachable */
406 		abort();
407 	}
408 
409 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
410 		fatal("socket: %s", strerror(errno));
411 
412 	v = 1;
413 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
414 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
415 
416 	v = 1;
417 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
418 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
419 
420 	mark_nonblock(sock);
421 
422 	if (bind(sock, addr, len) == -1)
423 		fatal("bind: %s", strerror(errno));
424 
425 	if (listen(sock, 16) == -1)
426 		fatal("listen: %s", strerror(errno));
427 
428 	return sock;
429 }
430 
431 void
432 setup_tls(void)
433 {
434 	struct tls_config *tlsconf;
435 	struct vhost *h;
436 
437 	if ((tlsconf = tls_config_new()) == NULL)
438 		fatal("tls_config_new");
439 
440 	/* optionally accept client certs, but don't try to verify them */
441 	tls_config_verify_client_optional(tlsconf);
442 	tls_config_insecure_noverifycert(tlsconf);
443 
444 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
445 		fatal("tls_config_set_protocols");
446 
447 	if ((ctx = tls_server()) == NULL)
448 		fatal("tls_server failure");
449 
450 	/* we need to set something, then we can add how many key we want */
451 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
452 		fatal("tls_config_set_keypair_file failed");
453 
454 	for (h = &hosts[1]; h->domain != NULL; ++h) {
455 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
456 			fatal("failed to load the keypair (%s, %s)",
457 			    h->cert, h->key);
458 	}
459 
460 	if (tls_configure(ctx, tlsconf) == -1)
461 		fatal("tls_configure: %s", tls_error(ctx));
462 }
463 
464 int
465 listener_main(void)
466 {
467 	int sock4, sock6;
468 
469 	load_default_mime(&conf.mime);
470 
471 	if (!conf.foreground && daemon(0, 1) == -1)
472 		exit(1);
473 
474 	sock4 = make_socket(conf.port, AF_INET);
475 	sock6 = -1;
476 	if (conf.ipv6)
477 		sock6 = make_socket(conf.port, AF_INET6);
478 
479 	load_vhosts();
480 
481 	sandbox();
482 	loop(ctx, sock4, sock6);
483 
484 	return 0;
485 }
486 
487 void
488 init_config(void)
489 {
490 	size_t i;
491 
492 	bzero(hosts, sizeof(hosts));
493 	for (i = 0; i < HOSTSLEN; ++i)
494 		hosts[i].dirfd = -1;
495 
496 	conf.foreground = 0;
497 	conf.port = 1965;
498 	conf.ipv6 = 0;
499 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
500 
501 	init_mime(&conf.mime);
502 
503 	conf.chroot = NULL;
504 	conf.user = NULL;
505 }
506 
507 void
508 drop_priv(void)
509 {
510 	struct passwd *pw = NULL;
511 
512 	if (conf.chroot != NULL && conf.user == NULL)
513 		fatal("can't chroot without an user to switch to after.");
514 
515 	if (conf.user != NULL) {
516 		if ((pw = getpwnam(conf.user)) == NULL)
517 			fatal("can't find user %s", conf.user);
518 	}
519 
520 	if (conf.chroot != NULL) {
521 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
522 			fatal("%s: %s", conf.chroot, strerror(errno));
523 	}
524 
525 	if (pw != NULL) {
526 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
527 			fatal("setresuid(%d): %s", pw->pw_uid,
528 			    strerror(errno));
529 	}
530 
531 	if (getuid() == 0)
532 		LOGW(NULL, "%s",
533 		    "not a good idea to run a network daemon as root");
534 }
535 
536 void
537 usage(const char *me)
538 {
539 	fprintf(stderr,
540 	    "USAGE: %s [-n] [-c config] | [-6h] [-d certs-dir] [-H host]"
541 	    "       [-p port] [-x cgi] [dir]",
542 	    me);
543 }
544 
545 int
546 main(int argc, char **argv)
547 {
548 	int ch, p[2];
549 	const char *config_path = NULL, *certs_dir = NULL, *hostname = NULL;
550 	int conftest = 0, configless = 0;
551 
552 	init_config();
553 
554 	while ((ch = getopt(argc, argv, "6c:d:H:hnp:x:")) != -1) {
555 		switch (ch) {
556 		case '6':
557 			conf.ipv6 = 1;
558 			configless = 1;
559 			break;
560 
561 		case 'c':
562 			config_path = optarg;
563 			break;
564 
565 		case 'd':
566 			certs_dir = optarg;
567 			configless = 1;
568 			break;
569 
570 		case 'H':
571 			hostname = optarg;
572 			configless = 1;
573 			break;
574 
575 		case 'h':
576 			usage(*argv);
577 			return 0;
578 
579 		case 'n':
580 			conftest = 1;
581 			break;
582 
583 		case 'p':
584 			conf.port = parse_portno(optarg);
585 			configless = 1;
586 			break;
587 
588 		case 'x':
589 			/* drop the starting / (if any) */
590 			if (*optarg == '/')
591 				optarg++;
592 			hosts[0].cgi = optarg;
593 			configless = 1;
594 			break;
595 
596 		default:
597 			usage(*argv);
598 			return 1;
599 		}
600 	}
601 	argc -= optind;
602 	argv += optind;
603 
604 	if (config_path != NULL) {
605 		if (argc > 0 || configless)
606 			fatal("can't specify options is config mode.");
607 
608 		parse_conf(config_path);
609 	} else {
610 		conf.foreground = 1;
611 
612 		if (hostname == NULL)
613 			hostname = "localhost";
614 		if (certs_dir == NULL)
615 			certs_dir = data_dir();
616 		load_local_cert(hostname, certs_dir);
617 
618                 switch (argc) {
619 		case 0:
620 			hosts[0].dir = ".";
621 			break;
622 		case 1:
623 			hosts[0].dir = argv[0];
624 			break;
625 		default:
626 			usage(getprogname());
627 			return 1;
628 		}
629 
630 		LOGN(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
631 	}
632 
633 	if (conftest) {
634 		puts("config OK");
635 		return 0;
636 	}
637 
638 	/* setup tls before dropping privileges: we don't want user
639 	 * to put private certs inside the chroot. */
640 	setup_tls();
641 	drop_priv();
642 
643 	signal(SIGPIPE, SIG_IGN);
644 	signal(SIGCHLD, SIG_IGN);
645 
646 #ifdef SIGINFO
647 	signal(SIGINFO, sig_handler);
648 #endif
649 	signal(SIGUSR2, sig_handler);
650 
651 	if (!conf.foreground) {
652 		signal(SIGHUP, SIG_IGN);
653 		if (daemon(1, 1) == -1)
654 			fatal("daemon: %s", strerror(errno));
655 	}
656 
657 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, p) == -1)
658 		fatal("socketpair: %s", strerror(errno));
659 
660 	switch (fork()) {
661 	case -1:
662 		fatal("fork: %s", strerror(errno));
663 
664 	case 0:			/* child */
665 		close(p[0]);
666 		exfd = p[1];
667 		listener_main();
668 		_exit(0);
669 
670 	default:		/* parent */
671 		close(p[1]);
672 		return executor_main(p[0]);
673 	}
674 }