libavformat: add mbedTLS based TLS
[libav.git] / libavformat / tls_mbedtls.c
1 /*
2 * TLS/SSL Protocol
3 * Copyright (c) 2018 Thomas Volkert
4 *
5 * This file is part of Libav.
6 *
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include <mbedtls/certs.h>
23 #include <mbedtls/config.h>
24 #include <mbedtls/ctr_drbg.h>
25 #include <mbedtls/entropy.h>
26 #include <mbedtls/net.h>
27 #include <mbedtls/platform.h>
28 #include <mbedtls/ssl.h>
29 #include <mbedtls/x509_crt.h>
30
31 #include "libavutil/parseutils.h"
32
33 #include "avformat.h"
34 #include "internal.h"
35 #include "tls.h"
36 #include "url.h"
37
38 typedef struct TLSContext {
39 const AVClass *class;
40 TLSShared tls_shared;
41 mbedtls_ssl_context ssl_context;
42 mbedtls_ssl_config ssl_config;
43 mbedtls_entropy_context entropy_context;
44 mbedtls_ctr_drbg_context ctr_drbg_context;
45 mbedtls_x509_crt ca_cert;
46 mbedtls_x509_crt own_cert;
47 mbedtls_pk_context priv_key;
48 char *priv_key_pw;
49 } TLSContext;
50
51 #define OFFSET(x) offsetof(TLSContext, x)
52
53 static int tls_close(URLContext *h)
54 {
55 TLSContext *tls_ctx = h->priv_data;
56
57 mbedtls_ssl_close_notify(&tls_ctx->ssl_context);
58 mbedtls_pk_free(&tls_ctx->priv_key);
59 mbedtls_x509_crt_free(&tls_ctx->ca_cert);
60 mbedtls_x509_crt_free(&tls_ctx->own_cert);
61 mbedtls_ssl_free(&tls_ctx->ssl_context);
62 mbedtls_ssl_config_free(&tls_ctx->ssl_config);
63 mbedtls_ctr_drbg_free(&tls_ctx->ctr_drbg_context);
64 mbedtls_entropy_free(&tls_ctx->entropy_context);
65
66 return 0;
67 }
68
69 static int handle_transport_error(URLContext *h, const char* func_name, int react_on_eagain, int ret)
70 {
71 switch (ret) {
72 case AVERROR(EAGAIN):
73 return react_on_eagain;
74 case AVERROR_EXIT:
75 return 0;
76 case AVERROR(EPIPE):
77 case AVERROR(ECONNRESET):
78 return MBEDTLS_ERR_NET_CONN_RESET;
79 default:
80 av_log(h, AV_LOG_ERROR, "%s returned 0x%x\n", func_name, ret);
81 errno = EIO;
82 return MBEDTLS_ERR_NET_SEND_FAILED;
83 }
84 }
85
86 static int mbedtls_send(void *ctx, const unsigned char *buf, size_t len)
87 {
88 URLContext *h = (URLContext*) ctx;
89 int ret = ffurl_write(h, buf, len);
90 if (ret >= 0)
91 return ret;
92
93 if (h->max_packet_size && len > h->max_packet_size)
94 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
95
96 return handle_transport_error(h, "ffurl_write", MBEDTLS_ERR_SSL_WANT_WRITE, ret);
97 }
98
99 static int mbedtls_recv(void *ctx, unsigned char *buf, size_t len)
100 {
101 URLContext *h = ctx;
102 int ret = ffurl_read(h, buf, len);
103 if (ret >= 0)
104 return ret;
105
106 if (h->max_packet_size && len > h->max_packet_size)
107 return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
108
109 return handle_transport_error(h, "ffurl_read", MBEDTLS_ERR_SSL_WANT_READ, ret);
110 }
111
112 static void handle_pk_parse_error(URLContext *h, int ret)
113 {
114 switch (ret) {
115 case MBEDTLS_ERR_PK_FILE_IO_ERROR:
116 av_log(h, AV_LOG_ERROR, "Read of key file failed. Is it actually there, are the access permissions correct?\n");
117 break;
118 case MBEDTLS_ERR_PK_PASSWORD_REQUIRED:
119 av_log(h, AV_LOG_ERROR, "A password for the private key is missing.\n");
120 break;
121 case MBEDTLS_ERR_PK_PASSWORD_MISMATCH:
122 av_log(h, AV_LOG_ERROR, "The given password for the private key is wrong.\n");
123 break;
124 default:
125 av_log(h, AV_LOG_ERROR, "mbedtls_pk_parse_key returned -0x%x\n", -ret);
126 break;
127 }
128 }
129
130 static void handle_handshake_error(URLContext *h, int ret)
131 {
132 switch (ret) {
133 case MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE:
134 av_log(h, AV_LOG_ERROR, "None of the common ciphersuites is usable. Was the local certificate set correctly?\n");
135 break;
136 case MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE:
137 av_log(h, AV_LOG_ERROR, "A fatal alert message was received from the peer. Does the peer have a correct certificate?\n");
138 break;
139 case MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED:
140 av_log(h, AV_LOG_ERROR, "No CA chain is set, but required to operate. Was the CA set correctly?\n");
141 break;
142 case MBEDTLS_ERR_NET_CONN_RESET:
143 av_log(h, AV_LOG_ERROR, "TLS handshake was aborted by peer.\n");
144 break;
145 default:
146 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_handshake returned -0x%x\n", -ret);
147 break;
148 }
149 }
150
151 static void parse_options(TLSContext *tls_ctxc, const char *uri)
152 {
153 char buf[1024];
154 const char *p = strchr(uri, '?');
155 if (!p)
156 return;
157
158 if (!tls_ctxc->priv_key_pw && av_find_info_tag(buf, sizeof(buf), "key_password", p))
159 tls_ctxc->priv_key_pw = av_strdup(buf);
160 }
161
162 static int tls_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
163 {
164 TLSContext *tls_ctx = h->priv_data;
165 TLSShared *shr = &tls_ctx->tls_shared;
166 uint32_t verify_res_flags;
167 int ret;
168
169 // parse additional options
170 parse_options(tls_ctx, uri);
171
172 if ((ret = ff_tls_open_underlying(shr, h, uri, options)) < 0)
173 goto fail;
174
175 mbedtls_ssl_init(&tls_ctx->ssl_context);
176 mbedtls_ssl_config_init(&tls_ctx->ssl_config);
177 mbedtls_entropy_init(&tls_ctx->entropy_context);
178 mbedtls_ctr_drbg_init(&tls_ctx->ctr_drbg_context);
179 mbedtls_x509_crt_init(&tls_ctx->ca_cert);
180 mbedtls_pk_init(&tls_ctx->priv_key);
181
182 // load trusted CA
183 if (shr->ca_file) {
184 if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->ca_cert, shr->ca_file)) != 0) {
185 av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for CA cert returned %d\n", ret);
186 goto fail;
187 }
188 }
189
190 // load own certificate
191 if (shr->cert_file) {
192 if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->own_cert, shr->cert_file)) != 0) {
193 av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for own cert returned %d\n", ret);
194 goto fail;
195 }
196 }
197
198 // load key file
199 if (shr->key_file) {
200 if ((ret = mbedtls_pk_parse_keyfile(&tls_ctx->priv_key,
201 shr->key_file,
202 tls_ctx->priv_key_pw)) != 0) {
203 handle_pk_parse_error(h, ret);
204 goto fail;
205 }
206 }
207
208 // seed the random number generator
209 if ((ret = mbedtls_ctr_drbg_seed(&tls_ctx->ctr_drbg_context,
210 mbedtls_entropy_func,
211 &tls_ctx->entropy_context,
212 NULL, 0)) != 0) {
213 av_log(h, AV_LOG_ERROR, "mbedtls_ctr_drbg_seed returned %d\n", ret);
214 goto fail;
215 }
216
217 if ((ret = mbedtls_ssl_config_defaults(&tls_ctx->ssl_config,
218 shr->listen ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT,
219 MBEDTLS_SSL_TRANSPORT_STREAM,
220 MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
221 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_config_defaults returned %d\n", ret);
222 goto fail;
223 }
224
225 mbedtls_ssl_conf_authmode(&tls_ctx->ssl_config,
226 shr->ca_file ? MBEDTLS_SSL_VERIFY_REQUIRED : MBEDTLS_SSL_VERIFY_NONE);
227 mbedtls_ssl_conf_rng(&tls_ctx->ssl_config, mbedtls_ctr_drbg_random, &tls_ctx->ctr_drbg_context);
228 mbedtls_ssl_conf_ca_chain(&tls_ctx->ssl_config, &tls_ctx->ca_cert, NULL);
229
230 // set own certificate and private key
231 if ((ret = mbedtls_ssl_conf_own_cert(&tls_ctx->ssl_config, &tls_ctx->own_cert, &tls_ctx->priv_key)) != 0) {
232 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_conf_own_cert returned %d\n", ret);
233 goto fail;
234 }
235
236 if ((ret = mbedtls_ssl_setup(&tls_ctx->ssl_context, &tls_ctx->ssl_config)) != 0) {
237 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_setup returned %d\n", ret);
238 goto fail;
239 }
240
241 if (!shr->listen && !shr->numerichost) {
242 if ((ret = mbedtls_ssl_set_hostname(&tls_ctx->ssl_context, shr->host)) != 0) {
243 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_set_hostname returned %d\n", ret);
244 goto fail;
245 }
246 }
247
248 // set I/O functions to use libavformat-internal code for transport layer
249 mbedtls_ssl_set_bio(&tls_ctx->ssl_context, shr->tcp, mbedtls_send, mbedtls_recv, NULL);
250
251 // ssl handshake
252 while ((ret = mbedtls_ssl_handshake(&tls_ctx->ssl_context)) != 0) {
253 if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
254 handle_handshake_error(h, ret);
255 goto fail;
256 }
257 }
258
259 if (shr->verify) {
260 // check the result of the certificate verification
261 if ((verify_res_flags = mbedtls_ssl_get_verify_result(&tls_ctx->ssl_context)) != 0) {
262 av_log(h, AV_LOG_ERROR, "mbedtls_ssl_get_verify_result reported problems "\
263 "with the certificate verification, returned flags: %u\n",
264 verify_res_flags);
265 if (verify_res_flags & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
266 av_log(h, AV_LOG_ERROR, "The certificate is not correctly signed by the trusted CA.\n");
267 goto fail;
268 }
269 }
270
271 return 0;
272
273 fail:
274 tls_close(h);
275 return AVERROR(EIO);
276 }
277
278 static int handle_tls_error(URLContext *h, const char *func_name, int ret)
279 {
280 switch (ret) {
281 case MBEDTLS_ERR_SSL_WANT_READ:
282 case MBEDTLS_ERR_SSL_WANT_WRITE:
283 return AVERROR(EAGAIN);
284 case MBEDTLS_ERR_NET_SEND_FAILED:
285 case MBEDTLS_ERR_NET_RECV_FAILED:
286 return AVERROR(EIO);
287 case MBEDTLS_ERR_NET_CONN_RESET:
288 case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
289 av_log(h, AV_LOG_WARNING, "%s reported connection reset by peer\n", func_name);
290 return AVERROR_EOF;
291 default:
292 av_log(h, AV_LOG_ERROR, "%s returned -0x%x\n", func_name, -ret);
293 return AVERROR(EIO);
294 }
295 }
296
297 static int tls_read(URLContext *h, uint8_t *buf, int size)
298 {
299 TLSContext *tls_ctx = h->priv_data;
300 int ret;
301
302 if ((ret = mbedtls_ssl_read(&tls_ctx->ssl_context, buf, size)) > 0) {
303 // return read length
304 return ret;
305 }
306
307 return handle_tls_error(h, "mbedtls_ssl_read", ret);
308 }
309
310 static int tls_write(URLContext *h, const uint8_t *buf, int size)
311 {
312 TLSContext *tls_ctx = h->priv_data;
313 int ret;
314
315 if ((ret = mbedtls_ssl_write(&tls_ctx->ssl_context, buf, size)) > 0) {
316 // return written length
317 return ret;
318 }
319
320 return handle_tls_error(h, "mbedtls_ssl_write", ret);
321 }
322
323 static int tls_get_file_handle(URLContext *h)
324 {
325 TLSContext *c = h->priv_data;
326 return ffurl_get_file_handle(c->tls_shared.tcp);
327 }
328
329 static const AVOption options[] = {
330 TLS_COMMON_OPTIONS(TLSContext, tls_shared), \
331 { "key_password", "Password for the private key file", OFFSET(priv_key_pw), AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
332 { NULL }
333 };
334
335 static const AVClass tls_class = {
336 .class_name = "tls",
337 .item_name = av_default_item_name,
338 .option = options,
339 .version = LIBAVUTIL_VERSION_INT,
340 };
341
342 const URLProtocol ff_tls_protocol = {
343 .name = "tls",
344 .url_open2 = tls_open,
345 .url_read = tls_read,
346 .url_write = tls_write,
347 .url_close = tls_close,
348 .url_get_file_handle = tls_get_file_handle,
349 .priv_data_size = sizeof(TLSContext),
350 .flags = URL_PROTOCOL_FLAG_NETWORK,
351 .priv_data_class = &tls_class,
352 };