aboutsummaryrefslogtreecommitdiffstats
path: root/libavformat/tls_mbedtls.c
blob: e802c6b872871e06061c6690c69d193fbf26fd02 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
/*
 * TLS/SSL Protocol
 * Copyright (c) 2018 Thomas Volkert
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <mbedtls/version.h>
#include <mbedtls/ctr_drbg.h>
#include <mbedtls/entropy.h>
#include <mbedtls/net_sockets.h>
#include <mbedtls/platform.h>
#include <mbedtls/ssl.h>
#include <mbedtls/x509_crt.h>
#include <mbedtls/debug.h>
#ifdef MBEDTLS_PSA_CRYPTO_C
#include <psa/crypto.h>
#endif

#include "avformat.h"
#include "internal.h"
#include "url.h"
#include "tls.h"
#include "libavutil/mem.h"
#include "libavutil/parseutils.h"
#include "libavutil/avstring.h"

typedef struct TLSContext {
    const AVClass *class;
    TLSShared tls_shared;
    mbedtls_ssl_context ssl_context;
    mbedtls_ssl_config ssl_config;
    mbedtls_entropy_context entropy_context;
    mbedtls_ctr_drbg_context ctr_drbg_context;
    mbedtls_x509_crt ca_cert;
    mbedtls_x509_crt own_cert;
    mbedtls_pk_context priv_key;
    char *priv_key_pw;
} TLSContext;

#define OFFSET(x) offsetof(TLSContext, x)

static int tls_close(URLContext *h)
{
    TLSContext *tls_ctx = h->priv_data;

    mbedtls_ssl_close_notify(&tls_ctx->ssl_context);
    mbedtls_pk_free(&tls_ctx->priv_key);
    mbedtls_x509_crt_free(&tls_ctx->ca_cert);
    mbedtls_x509_crt_free(&tls_ctx->own_cert);
    mbedtls_ssl_free(&tls_ctx->ssl_context);
    mbedtls_ssl_config_free(&tls_ctx->ssl_config);
    mbedtls_ctr_drbg_free(&tls_ctx->ctr_drbg_context);
    mbedtls_entropy_free(&tls_ctx->entropy_context);

    ffurl_closep(&tls_ctx->tls_shared.tcp);
    return 0;
}

static int handle_transport_error(URLContext *h, const char* func_name, int react_on_eagain, int ret)
{
    switch (ret) {
    case AVERROR(EAGAIN):
        return react_on_eagain;
    case AVERROR_EXIT:
        return 0;
    case AVERROR(EPIPE):
    case AVERROR(ECONNRESET):
        return MBEDTLS_ERR_NET_CONN_RESET;
    default:
        av_log(h, AV_LOG_ERROR, "%s returned 0x%x\n", func_name, ret);
        errno = EIO;
        return MBEDTLS_ERR_NET_SEND_FAILED;
    }
}

static int mbedtls_send(void *ctx, const unsigned char *buf, size_t len)
{
    URLContext *h = (URLContext*) ctx;
    int ret = ffurl_write(h, buf, len);
    if (ret >= 0)
        return ret;

    if (h->max_packet_size && len > h->max_packet_size)
        return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;

    return handle_transport_error(h, "ffurl_write", MBEDTLS_ERR_SSL_WANT_WRITE, ret);
}

static int mbedtls_recv(void *ctx, unsigned char *buf, size_t len)
{
    URLContext *h = (URLContext*) ctx;
    int ret = ffurl_read(h, buf, len);
    if (ret >= 0)
        return ret;

    if (h->max_packet_size && len > h->max_packet_size)
        return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;

    return handle_transport_error(h, "ffurl_read", MBEDTLS_ERR_SSL_WANT_READ, ret);
}

static void mbedtls_debug(void *ctx, int lvl, const char *file, int line, const char *msg)
{
    URLContext *h = (URLContext*) ctx;
    int av_lvl = lvl >= 4 ? AV_LOG_TRACE : AV_LOG_DEBUG;
    av_log(h, av_lvl, "%s:%d: %s", av_basename(file), line, msg);
}

static void handle_pk_parse_error(URLContext *h, int ret)
{
    switch (ret) {
    case MBEDTLS_ERR_PK_FILE_IO_ERROR:
        av_log(h, AV_LOG_ERROR, "Read of key file failed. Is it actually there, are the access permissions correct?\n");
        break;
    case MBEDTLS_ERR_PK_PASSWORD_REQUIRED:
        av_log(h, AV_LOG_ERROR, "A password for the private key is missing.\n");
        break;
    case MBEDTLS_ERR_PK_PASSWORD_MISMATCH:
        av_log(h, AV_LOG_ERROR, "The given password for the private key is wrong.\n");
        break;
    default:
        av_log(h, AV_LOG_ERROR, "mbedtls_pk_parse_key returned -0x%x\n", -ret);
        break;
    }
}

static void handle_handshake_error(URLContext *h, int ret)
{
    switch (ret) {
#if MBEDTLS_VERSION_MAJOR < 3
    case MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE:
        av_log(h, AV_LOG_ERROR, "None of the common ciphersuites is usable. Was the local certificate correctly set?\n");
        break;
#else
    case MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE:
        av_log(h, AV_LOG_ERROR, "TLS handshake failed.\n");
        break;
    case MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION:
        av_log(h, AV_LOG_ERROR, "TLS protocol version mismatch.\n");
        break;
#endif
    case MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE:
        av_log(h, AV_LOG_ERROR, "A fatal alert message was received from the peer, has the peer a correct certificate?\n");
        break;
    case MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED:
        av_log(h, AV_LOG_ERROR, "No CA chain is set, but required to operate. Was the CA correctly set?\n");
        break;
    case MBEDTLS_ERR_SSL_INTERNAL_ERROR:
        av_log(h, AV_LOG_ERROR, "Internal error encountered.\n");
        break;
    case MBEDTLS_ERR_NET_CONN_RESET:
        av_log(h, AV_LOG_ERROR, "TLS handshake was aborted by peer.\n");
        break;
    case MBEDTLS_ERR_X509_CERT_VERIFY_FAILED:
        av_log(h, AV_LOG_ERROR, "Certificate verification failed.\n");
        break;
    default:
        av_log(h, AV_LOG_ERROR, "mbedtls_ssl_handshake returned -0x%x\n", -ret);
        break;
    }
}

static void parse_options(TLSContext *tls_ctxc, const char *uri)
{
    char buf[1024];
    const char *p = strchr(uri, '?');
    if (!p)
        return;

    if (!tls_ctxc->priv_key_pw && av_find_info_tag(buf, sizeof(buf), "key_password", p))
        tls_ctxc->priv_key_pw = av_strdup(buf);
}

static int tls_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
{
    TLSContext *tls_ctx = h->priv_data;
    TLSShared *shr = &tls_ctx->tls_shared;
    uint32_t verify_res_flags;
    int ret;

    // parse additional options
    parse_options(tls_ctx, uri);

    if ((ret = ff_tls_open_underlying(shr, h, uri, options)) < 0)
        goto fail;

#ifdef MBEDTLS_PSA_CRYPTO_C
    if ((ret = psa_crypto_init()) != PSA_SUCCESS) {
        av_log(h, AV_LOG_ERROR, "psa_crypto_init returned %d\n", ret);
        goto fail;
    }
#endif

    mbedtls_ssl_init(&tls_ctx->ssl_context);
    mbedtls_ssl_config_init(&tls_ctx->ssl_config);
    mbedtls_entropy_init(&tls_ctx->entropy_context);
    mbedtls_ctr_drbg_init(&tls_ctx->ctr_drbg_context);
    mbedtls_x509_crt_init(&tls_ctx->ca_cert);
    mbedtls_pk_init(&tls_ctx->priv_key);

    if (av_log_get_level() >= AV_LOG_DEBUG) {
        mbedtls_ssl_conf_dbg(&tls_ctx->ssl_config, mbedtls_debug, shr->tcp);
        /*
         * Note: we can't call mbedtls_debug_set_threshold() here because
         * it's global state. The user is thus expected to manage this.
         */
    }

    // load trusted CA
    if (shr->ca_file) {
        if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->ca_cert, shr->ca_file)) != 0) {
            av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for CA cert returned %d\n", ret);
            goto fail;
        }
    }

    // load own certificate
    if (shr->cert_file) {
        if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->own_cert, shr->cert_file)) != 0) {
            av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for own cert returned %d\n", ret);
            goto fail;
        }
    }

    // seed the random number generator
    if ((ret = mbedtls_ctr_drbg_seed(&tls_ctx->ctr_drbg_context,
                                     mbedtls_entropy_func,
                                     &tls_ctx->entropy_context,
                                     NULL, 0)) != 0) {
        av_log(h, AV_LOG_ERROR, "mbedtls_ctr_drbg_seed returned %d\n", ret);
        goto fail;
    }

    // load key file
    if (shr->key_file) {
        if ((ret = mbedtls_pk_parse_keyfile(&tls_ctx->priv_key,
                                            shr->key_file,
                                            tls_ctx->priv_key_pw
#if MBEDTLS_VERSION_MAJOR >= 3
                                            , mbedtls_ctr_drbg_random,
                                            &tls_ctx->ctr_drbg_context
#endif
                                            )) != 0) {
            handle_pk_parse_error(h, ret);
            goto fail;
        }
    }

    if ((ret = mbedtls_ssl_config_defaults(&tls_ctx->ssl_config,
                                           shr->listen ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT,
                                           MBEDTLS_SSL_TRANSPORT_STREAM,
                                           MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
        av_log(h, AV_LOG_ERROR, "mbedtls_ssl_config_defaults returned %d\n", ret);
        goto fail;
    }

#ifdef MBEDTLS_SSL_PROTO_TLS1_3
    // this version does not allow disabling certificate verification with TLSv1.3 (yes, really).
    if (mbedtls_version_get_number() == 0x03060000 && !shr->verify) {
        av_log(h, AV_LOG_INFO, "Forcing TLSv1.2 because certificate verification is disabled\n");
        mbedtls_ssl_conf_max_tls_version(&tls_ctx->ssl_config, MBEDTLS_SSL_VERSION_TLS1_2);
    }
#endif

    // not VERIFY_REQUIRED because we manually check after handshake
    mbedtls_ssl_conf_authmode(&tls_ctx->ssl_config,
                              shr->verify ? MBEDTLS_SSL_VERIFY_OPTIONAL : MBEDTLS_SSL_VERIFY_NONE);
    mbedtls_ssl_conf_rng(&tls_ctx->ssl_config, mbedtls_ctr_drbg_random, &tls_ctx->ctr_drbg_context);
    mbedtls_ssl_conf_ca_chain(&tls_ctx->ssl_config, &tls_ctx->ca_cert, NULL);

    // set own certificate and private key
    if ((ret = mbedtls_ssl_conf_own_cert(&tls_ctx->ssl_config, &tls_ctx->own_cert, &tls_ctx->priv_key)) != 0) {
        av_log(h, AV_LOG_ERROR, "mbedtls_ssl_conf_own_cert returned %d\n", ret);
        goto fail;
    }

    if ((ret = mbedtls_ssl_setup(&tls_ctx->ssl_context, &tls_ctx->ssl_config)) != 0) {
        av_log(h, AV_LOG_ERROR, "mbedtls_ssl_setup returned %d\n", ret);
        goto fail;
    }

    if (!shr->listen && !shr->numerichost) {
        if ((ret = mbedtls_ssl_set_hostname(&tls_ctx->ssl_context, shr->host)) != 0) {
            av_log(h, AV_LOG_ERROR, "mbedtls_ssl_set_hostname returned %d\n", ret);
            goto fail;
        }
    }

    // set I/O functions to use FFmpeg internal code for transport layer
    mbedtls_ssl_set_bio(&tls_ctx->ssl_context, shr->tcp, mbedtls_send, mbedtls_recv, NULL);

    // ssl handshake
    while ((ret = mbedtls_ssl_handshake(&tls_ctx->ssl_context)) != 0) {
        if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
            handle_handshake_error(h, ret);
            goto fail;
        }
    }

    if (shr->verify) {
        // check the result of the certificate verification
        if ((verify_res_flags = mbedtls_ssl_get_verify_result(&tls_ctx->ssl_context)) != 0) {
            av_log(h, AV_LOG_ERROR, "mbedtls_ssl_get_verify_result reported problems "\
                                    "with the certificate verification, returned flags: %u\n",
                                    verify_res_flags);
            if (verify_res_flags & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
                av_log(h, AV_LOG_ERROR, "The certificate is not correctly signed by the trusted CA.\n");
            goto fail;
        }
    }

    return 0;

fail:
    tls_close(h);
    return AVERROR(EIO);
}

static int handle_tls_error(URLContext *h, const char* func_name, int ret)
{
    switch (ret) {
    case MBEDTLS_ERR_SSL_WANT_READ:
    case MBEDTLS_ERR_SSL_WANT_WRITE:
#ifdef MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET
    case MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET:
#endif
        return AVERROR(EAGAIN);
    case MBEDTLS_ERR_NET_SEND_FAILED:
    case MBEDTLS_ERR_NET_RECV_FAILED:
        return AVERROR(EIO);
    case MBEDTLS_ERR_NET_CONN_RESET:
    case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
        av_log(h, AV_LOG_WARNING, "%s reported connection reset by peer\n", func_name);
        return AVERROR_EOF;
    default:
        av_log(h, AV_LOG_ERROR, "%s returned -0x%x\n", func_name, -ret);
        return AVERROR(EIO);
    }
}

static int tls_read(URLContext *h, uint8_t *buf, int size)
{
    TLSContext *tls_ctx = h->priv_data;
    int ret;

    tls_ctx->tls_shared.tcp->flags &= ~AVIO_FLAG_NONBLOCK;
    tls_ctx->tls_shared.tcp->flags |= h->flags & AVIO_FLAG_NONBLOCK;
    if ((ret = mbedtls_ssl_read(&tls_ctx->ssl_context, buf, size)) > 0) {
        // return read length
        return ret;
    }

    return handle_tls_error(h, "mbedtls_ssl_read", ret);
}

static int tls_write(URLContext *h, const uint8_t *buf, int size)
{
    TLSContext *tls_ctx = h->priv_data;
    int ret;

    tls_ctx->tls_shared.tcp->flags &= ~AVIO_FLAG_NONBLOCK;
    tls_ctx->tls_shared.tcp->flags |= h->flags & AVIO_FLAG_NONBLOCK;
    if ((ret = mbedtls_ssl_write(&tls_ctx->ssl_context, buf, size)) > 0) {
        // return written length
        return ret;
    }

    return handle_tls_error(h, "mbedtls_ssl_write", ret);
}

static int tls_get_file_handle(URLContext *h)
{
    TLSContext *c = h->priv_data;
    return ffurl_get_file_handle(c->tls_shared.tcp);
}

static int tls_get_short_seek(URLContext *h)
{
    TLSContext *s = h->priv_data;
    return ffurl_get_short_seek(s->tls_shared.tcp);
}

static const AVOption options[] = {
    TLS_COMMON_OPTIONS(TLSContext, tls_shared), \
    {"key_password", "Password for the private key file", OFFSET(priv_key_pw),  AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
    { NULL }
};

static const AVClass tls_class = {
    .class_name = "tls",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

const URLProtocol ff_tls_protocol = {
    .name           = "tls",
    .url_open2      = tls_open,
    .url_read       = tls_read,
    .url_write      = tls_write,
    .url_close      = tls_close,
    .url_get_file_handle = tls_get_file_handle,
    .url_get_short_seek  = tls_get_short_seek,
    .priv_data_size = sizeof(TLSContext),
    .flags          = URL_PROTOCOL_FLAG_NETWORK,
    .priv_data_class = &tls_class,
};