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