xref: /openbsd-src/lib/libtls/tls_client.c (revision 3d61058aa5c692477b6d18acfbbdb653a9930ff9) 
1 /* $OpenBSD: tls_client.c,v 1.51 2024/03/26 08:54:48 joshua Exp $ */
2 /*
3  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/socket.h>
20 #include <sys/stat.h>
21 
22 #include <arpa/inet.h>
23 #include <netinet/in.h>
24 
25 #include <limits.h>
26 #include <netdb.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30 
31 #include <openssl/err.h>
32 #include <openssl/x509.h>
33 
34 #include <tls.h>
35 #include "tls_internal.h"
36 
37 struct tls *
38 tls_client(void)
39 {
40 	struct tls *ctx;
41 
42 	if (tls_init() == -1)
43 		return (NULL);
44 
45 	if ((ctx = tls_new()) == NULL)
46 		return (NULL);
47 
48 	ctx->flags |= TLS_CLIENT;
49 
50 	return (ctx);
51 }
52 
53 int
54 tls_connect(struct tls *ctx, const char *host, const char *port)
55 {
56 	return tls_connect_servername(ctx, host, port, NULL);
57 }
58 
59 int
60 tls_connect_servername(struct tls *ctx, const char *host, const char *port,
61     const char *servername)
62 {
63 	struct addrinfo hints, *res, *res0;
64 	const char *h = NULL, *p = NULL;
65 	char *hs = NULL, *ps = NULL;
66 	int rv = -1, s = -1, ret;
67 
68 	if ((ctx->flags & TLS_CLIENT) == 0) {
69 		tls_set_errorx(ctx, TLS_ERROR_INVALID_CONTEXT,
70 		    "not a client context");
71 		goto err;
72 	}
73 
74 	if (host == NULL) {
75 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "host not specified");
76 		goto err;
77 	}
78 
79 	/* If port is NULL, try to extract a port from the specified host. */
80 	if (port == NULL) {
81 		ret = tls_host_port(host, &hs, &ps);
82 		if (ret == -1) {
83 			tls_set_errorx(ctx, TLS_ERROR_OUT_OF_MEMORY, "out of memory");
84 			goto err;
85 		}
86 		if (ret != 0) {
87 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "no port provided");
88 			goto err;
89 		}
90 	}
91 
92 	h = (hs != NULL) ? hs : host;
93 	p = (ps != NULL) ? ps : port;
94 
95 	/*
96 	 * First check if the host is specified as a numeric IP address,
97 	 * either IPv4 or IPv6, before trying to resolve the host.
98 	 * The AI_ADDRCONFIG resolver option will not return IPv4 or IPv6
99 	 * records if it is not configured on an interface;  not considering
100 	 * loopback addresses.  Checking the numeric addresses first makes
101 	 * sure that connection attempts to numeric addresses and especially
102 	 * 127.0.0.1 or ::1 loopback addresses are always possible.
103 	 */
104 	memset(&hints, 0, sizeof(hints));
105 	hints.ai_socktype = SOCK_STREAM;
106 
107 	/* try as an IPv4 literal */
108 	hints.ai_family = AF_INET;
109 	hints.ai_flags = AI_NUMERICHOST;
110 	if (getaddrinfo(h, p, &hints, &res0) != 0) {
111 		/* try again as an IPv6 literal */
112 		hints.ai_family = AF_INET6;
113 		if (getaddrinfo(h, p, &hints, &res0) != 0) {
114 			/* last try, with name resolution and save the error */
115 			hints.ai_family = AF_UNSPEC;
116 			hints.ai_flags = AI_ADDRCONFIG;
117 			if ((s = getaddrinfo(h, p, &hints, &res0)) != 0) {
118 				tls_set_error(ctx, TLS_ERROR_UNKNOWN,
119 				    "%s", gai_strerror(s));
120 				goto err;
121 			}
122 		}
123 	}
124 
125 	/* It was resolved somehow; now try connecting to what we got */
126 	s = -1;
127 	for (res = res0; res; res = res->ai_next) {
128 		s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
129 		if (s == -1) {
130 			tls_set_error(ctx, TLS_ERROR_UNKNOWN,
131 			    "socket");
132 			continue;
133 		}
134 		if (connect(s, res->ai_addr, res->ai_addrlen) == -1) {
135 			tls_set_error(ctx, TLS_ERROR_UNKNOWN,
136 			    "connect");
137 			close(s);
138 			s = -1;
139 			continue;
140 		}
141 
142 		break;  /* Connected. */
143 	}
144 	freeaddrinfo(res0);
145 
146 	if (s == -1)
147 		goto err;
148 
149 	if (servername == NULL)
150 		servername = h;
151 
152 	if (tls_connect_socket(ctx, s, servername) != 0) {
153 		close(s);
154 		goto err;
155 	}
156 
157 	ctx->socket = s;
158 
159 	rv = 0;
160 
161  err:
162 	free(hs);
163 	free(ps);
164 
165 	return (rv);
166 }
167 
168 static int
169 tls_client_read_session(struct tls *ctx)
170 {
171 	int sfd = ctx->config->session_fd;
172 	uint8_t *session = NULL;
173 	size_t session_len = 0;
174 	SSL_SESSION *ss = NULL;
175 	BIO *bio = NULL;
176 	struct stat sb;
177 	ssize_t n;
178 	int rv = -1;
179 
180 	if (fstat(sfd, &sb) == -1) {
181 		tls_set_error(ctx, TLS_ERROR_UNKNOWN,
182 		    "failed to stat session file");
183 		goto err;
184 	}
185 	if (sb.st_size < 0 || sb.st_size > INT_MAX) {
186 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
187 		    "invalid session file size");
188 		goto err;
189 	}
190 	session_len = (size_t)sb.st_size;
191 
192 	/* A zero size file means that we do not yet have a valid session. */
193 	if (session_len == 0)
194 		goto done;
195 
196 	if ((session = malloc(session_len)) == NULL)
197 		goto err;
198 
199 	n = pread(sfd, session, session_len, 0);
200 	if (n < 0 || (size_t)n != session_len) {
201 		tls_set_error(ctx, TLS_ERROR_UNKNOWN,
202 		    "failed to read session file");
203 		goto err;
204 	}
205 	if ((bio = BIO_new_mem_buf(session, session_len)) == NULL)
206 		goto err;
207 	if ((ss = PEM_read_bio_SSL_SESSION(bio, NULL, tls_password_cb,
208 	    NULL)) == NULL) {
209 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
210 		    "failed to parse session");
211 		goto err;
212 	}
213 
214 	if (SSL_set_session(ctx->ssl_conn, ss) != 1) {
215 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
216 		    "failed to set session");
217 		goto err;
218 	}
219 
220  done:
221 	rv = 0;
222 
223  err:
224 	freezero(session, session_len);
225 	SSL_SESSION_free(ss);
226 	BIO_free(bio);
227 
228 	return rv;
229 }
230 
231 static int
232 tls_client_write_session(struct tls *ctx)
233 {
234 	int sfd = ctx->config->session_fd;
235 	SSL_SESSION *ss = NULL;
236 	BIO *bio = NULL;
237 	long data_len;
238 	char *data;
239 	off_t offset;
240 	size_t len;
241 	ssize_t n;
242 	int rv = -1;
243 
244 	if ((ss = SSL_get1_session(ctx->ssl_conn)) == NULL) {
245 		if (ftruncate(sfd, 0) == -1) {
246 			tls_set_error(ctx, TLS_ERROR_UNKNOWN,
247 			    "failed to truncate session file");
248 			goto err;
249 		}
250 		goto done;
251 	}
252 
253 	if ((bio = BIO_new(BIO_s_mem())) == NULL)
254 		goto err;
255 	if (PEM_write_bio_SSL_SESSION(bio, ss) == 0)
256 		goto err;
257 	if ((data_len = BIO_get_mem_data(bio, &data)) <= 0)
258 		goto err;
259 
260 	len = (size_t)data_len;
261 	offset = 0;
262 
263 	if (ftruncate(sfd, len) == -1) {
264 		tls_set_error(ctx, TLS_ERROR_UNKNOWN,
265 		    "failed to truncate session file");
266 		goto err;
267 	}
268 	while (len > 0) {
269 		if ((n = pwrite(sfd, data + offset, len, offset)) == -1) {
270 			tls_set_error(ctx, TLS_ERROR_UNKNOWN,
271 			    "failed to write session file");
272 			goto err;
273 		}
274 		offset += n;
275 		len -= n;
276 	}
277 
278  done:
279 	rv = 0;
280 
281  err:
282 	SSL_SESSION_free(ss);
283 	BIO_free_all(bio);
284 
285 	return (rv);
286 }
287 
288 static int
289 tls_connect_common(struct tls *ctx, const char *servername)
290 {
291 	union tls_addr addrbuf;
292 	size_t servername_len;
293 	int rv = -1;
294 
295 	if ((ctx->flags & TLS_CLIENT) == 0) {
296 		tls_set_errorx(ctx, TLS_ERROR_INVALID_CONTEXT,
297 		    "not a client context");
298 		goto err;
299 	}
300 
301 	if (servername != NULL) {
302 		if ((ctx->servername = strdup(servername)) == NULL) {
303 			tls_set_errorx(ctx, TLS_ERROR_OUT_OF_MEMORY,
304 			    "out of memory");
305 			goto err;
306 		}
307 
308 		/*
309 		 * If there's a trailing dot, remove it. While an FQDN includes
310 		 * the terminating dot representing the zero-length label of
311 		 * the root (RFC 8499, section 2), the SNI explicitly does not
312 		 * include it (RFC 6066, section 3).
313 		 */
314 		servername_len = strlen(ctx->servername);
315 		if (servername_len > 0 &&
316 		    ctx->servername[servername_len - 1] == '.')
317 			ctx->servername[servername_len - 1] = '\0';
318 	}
319 
320 	if ((ctx->ssl_ctx = SSL_CTX_new(SSLv23_client_method())) == NULL) {
321 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "ssl context failure");
322 		goto err;
323 	}
324 
325 	if (tls_configure_ssl(ctx, ctx->ssl_ctx) != 0)
326 		goto err;
327 
328 	if (tls_configure_ssl_keypair(ctx, ctx->ssl_ctx,
329 	    ctx->config->keypair, 0) != 0)
330 		goto err;
331 
332 	if (ctx->config->verify_name) {
333 		if (ctx->servername == NULL) {
334 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
335 			    "server name not specified");
336 			goto err;
337 		}
338 	}
339 
340 	if (tls_configure_ssl_verify(ctx, ctx->ssl_ctx, SSL_VERIFY_PEER) == -1)
341 		goto err;
342 
343 	if (ctx->config->ecdhecurves != NULL) {
344 		if (SSL_CTX_set1_groups(ctx->ssl_ctx, ctx->config->ecdhecurves,
345 		    ctx->config->ecdhecurves_len) != 1) {
346 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
347 			    "failed to set ecdhe curves");
348 			goto err;
349 		}
350 	}
351 
352 	if (SSL_CTX_set_tlsext_status_cb(ctx->ssl_ctx, tls_ocsp_verify_cb) != 1) {
353 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
354 		    "ssl OCSP verification setup failure");
355 		goto err;
356 	}
357 
358 	if ((ctx->ssl_conn = SSL_new(ctx->ssl_ctx)) == NULL) {
359 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "ssl connection failure");
360 		goto err;
361 	}
362 
363 	if (SSL_set_app_data(ctx->ssl_conn, ctx) != 1) {
364 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
365 		    "ssl application data failure");
366 		goto err;
367 	}
368 
369 	if (ctx->config->session_fd != -1) {
370 		SSL_clear_options(ctx->ssl_conn, SSL_OP_NO_TICKET);
371 		if (tls_client_read_session(ctx) == -1)
372 			goto err;
373 	}
374 
375 	if (SSL_set_tlsext_status_type(ctx->ssl_conn, TLSEXT_STATUSTYPE_ocsp) != 1) {
376 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
377 		    "ssl OCSP extension setup failure");
378 		goto err;
379 	}
380 
381 	/*
382 	 * RFC 6066 (SNI): Literal IPv4 and IPv6 addresses are not
383 	 * permitted in "HostName".
384 	 */
385 	if (ctx->servername != NULL &&
386 	    inet_pton(AF_INET, ctx->servername, &addrbuf) != 1 &&
387 	    inet_pton(AF_INET6, ctx->servername, &addrbuf) != 1) {
388 		if (SSL_set_tlsext_host_name(ctx->ssl_conn,
389 		    ctx->servername) == 0) {
390 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
391 			    "server name indication failure");
392 			goto err;
393 		}
394 	}
395 
396 	ctx->state |= TLS_CONNECTED;
397 	rv = 0;
398 
399  err:
400 	return (rv);
401 }
402 
403 int
404 tls_connect_socket(struct tls *ctx, int s, const char *servername)
405 {
406 	return tls_connect_fds(ctx, s, s, servername);
407 }
408 
409 int
410 tls_connect_fds(struct tls *ctx, int fd_read, int fd_write,
411     const char *servername)
412 {
413 	int rv = -1;
414 
415 	if (fd_read < 0 || fd_write < 0) {
416 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "invalid file descriptors");
417 		goto err;
418 	}
419 
420 	if (tls_connect_common(ctx, servername) != 0)
421 		goto err;
422 
423 	if (SSL_set_rfd(ctx->ssl_conn, fd_read) != 1 ||
424 	    SSL_set_wfd(ctx->ssl_conn, fd_write) != 1) {
425 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
426 		    "ssl file descriptor failure");
427 		goto err;
428 	}
429 
430 	rv = 0;
431  err:
432 	return (rv);
433 }
434 
435 int
436 tls_connect_cbs(struct tls *ctx, tls_read_cb read_cb,
437     tls_write_cb write_cb, void *cb_arg, const char *servername)
438 {
439 	int rv = -1;
440 
441 	if (tls_connect_common(ctx, servername) != 0)
442 		goto err;
443 
444 	if (tls_set_cbs(ctx, read_cb, write_cb, cb_arg) != 0)
445 		goto err;
446 
447 	rv = 0;
448 
449  err:
450 	return (rv);
451 }
452 
453 int
454 tls_handshake_client(struct tls *ctx)
455 {
456 	X509 *cert = NULL;
457 	int match, ssl_ret;
458 	int rv = -1;
459 
460 	if ((ctx->flags & TLS_CLIENT) == 0) {
461 		tls_set_errorx(ctx, TLS_ERROR_INVALID_CONTEXT,
462 		    "not a client context");
463 		goto err;
464 	}
465 
466 	if ((ctx->state & TLS_CONNECTED) == 0) {
467 		tls_set_errorx(ctx, TLS_ERROR_UNKNOWN, "context not connected");
468 		goto err;
469 	}
470 
471 	ctx->state |= TLS_SSL_NEEDS_SHUTDOWN;
472 
473 	ERR_clear_error();
474 	if ((ssl_ret = SSL_connect(ctx->ssl_conn)) != 1) {
475 		rv = tls_ssl_error(ctx, ctx->ssl_conn, ssl_ret, "handshake");
476 		goto err;
477 	}
478 
479 	if (ctx->config->verify_name) {
480 		cert = SSL_get_peer_certificate(ctx->ssl_conn);
481 		if (cert == NULL) {
482 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
483 			    "no server certificate");
484 			goto err;
485 		}
486 		if (tls_check_name(ctx, cert, ctx->servername, &match) == -1)
487 			goto err;
488 		if (!match) {
489 			tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
490 			    "name `%s' not present in server certificate",
491 			    ctx->servername);
492 			goto err;
493 		}
494 	}
495 
496 	ctx->state |= TLS_HANDSHAKE_COMPLETE;
497 
498 	if (ctx->config->session_fd != -1) {
499 		if (tls_client_write_session(ctx) == -1)
500 			goto err;
501 	}
502 
503 	rv = 0;
504 
505  err:
506 	X509_free(cert);
507 
508 	return (rv);
509 }
510