libavformat/tls_mbedtls.c

   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/version.h>
  23 #include <mbedtls/ctr_drbg.h>
  24 #include <mbedtls/entropy.h>
  25 #include <mbedtls/net_sockets.h>
  26 #include <mbedtls/platform.h>
  27 #include <mbedtls/ssl.h>
  28 #include <mbedtls/x509_crt.h>
  29 #include <mbedtls/debug.h>
  30 #ifdef MBEDTLS_PSA_CRYPTO_C
  31 #include <psa/crypto.h>
  32 #endif
  33
  34 #include "avformat.h"
  35 #include "internal.h"
  36 #include "url.h"
  37 #include "tls.h"
  38 #include "libavutil/mem.h"
  39 #include "libavutil/parseutils.h"
  40 #include "libavutil/avstring.h"
  41
  42 typedef struct TLSContext {
  43     TLSShared tls_shared;
  44     mbedtls_ssl_context ssl_context;
  45     mbedtls_ssl_config ssl_config;
  46     mbedtls_entropy_context entropy_context;
  47     mbedtls_ctr_drbg_context ctr_drbg_context;
  48     mbedtls_x509_crt ca_cert;
  49     mbedtls_x509_crt own_cert;
  50     mbedtls_pk_context priv_key;
  51     char *priv_key_pw;
  52 } TLSContext;
  53
  54 #define OFFSET(x) offsetof(TLSContext, x)
  55
  56 static int tls_close(URLContext *h)
  57 {
  58     TLSContext *tls_ctx = h->priv_data;
  59
  60     mbedtls_ssl_close_notify(&tls_ctx->ssl_context);
  61     mbedtls_pk_free(&tls_ctx->priv_key);
  62     mbedtls_x509_crt_free(&tls_ctx->ca_cert);
  63     mbedtls_x509_crt_free(&tls_ctx->own_cert);
  64     mbedtls_ssl_free(&tls_ctx->ssl_context);
  65     mbedtls_ssl_config_free(&tls_ctx->ssl_config);
  66     mbedtls_ctr_drbg_free(&tls_ctx->ctr_drbg_context);
  67     mbedtls_entropy_free(&tls_ctx->entropy_context);
  68
  69     ffurl_closep(&tls_ctx->tls_shared.tcp);
  70     return 0;
  71 }
  72
  73 static int handle_transport_error(URLContext *h, const char* func_name, int react_on_eagain, int ret)
  74 {
  75     switch (ret) {
  76     case AVERROR(EAGAIN):
  77         return react_on_eagain;
  78     case AVERROR_EXIT:
  79         return 0;
  80     case AVERROR(EPIPE):
  81     case AVERROR(ECONNRESET):
  82         return MBEDTLS_ERR_NET_CONN_RESET;
  83     default:
  84         av_log(h, AV_LOG_ERROR, "%s returned 0x%x\n", func_name, ret);
  85         errno = EIO;
  86         return MBEDTLS_ERR_NET_SEND_FAILED;
  87     }
  88 }
  89
  90 static int mbedtls_send(void *ctx, const unsigned char *buf, size_t len)
  91 {
  92     URLContext *h = (URLContext*) ctx;
  93     int ret = ffurl_write(h, buf, len);
  94     if (ret >= 0)
  95         return ret;
  96
  97     if (h->max_packet_size && len > h->max_packet_size)
  98         return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
  99
 100     return handle_transport_error(h, "ffurl_write", MBEDTLS_ERR_SSL_WANT_WRITE, ret);
 101 }
 102
 103 static int mbedtls_recv(void *ctx, unsigned char *buf, size_t len)
 104 {
 105     URLContext *h = (URLContext*) ctx;
 106     int ret = ffurl_read(h, buf, len);
 107     if (ret >= 0)
 108         return ret;
 109
 110     if (h->max_packet_size && len > h->max_packet_size)
 111         return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
 112
 113     return handle_transport_error(h, "ffurl_read", MBEDTLS_ERR_SSL_WANT_READ, ret);
 114 }
 115
 116 static void mbedtls_debug(void *ctx, int lvl, const char *file, int line, const char *msg)
 117 {
 118     URLContext *h = (URLContext*) ctx;
 119     int av_lvl = lvl >= 4 ? AV_LOG_TRACE : AV_LOG_DEBUG;
 120     av_log(h, av_lvl, "%s:%d: %s", av_basename(file), line, msg);
 121 }
 122
 123 static void handle_pk_parse_error(URLContext *h, int ret)
 124 {
 125     switch (ret) {
 126     case MBEDTLS_ERR_PK_FILE_IO_ERROR:
 127         av_log(h, AV_LOG_ERROR, "Read of key file failed. Is it actually there, are the access permissions correct?\n");
 128         break;
 129     case MBEDTLS_ERR_PK_PASSWORD_REQUIRED:
 130         av_log(h, AV_LOG_ERROR, "A password for the private key is missing.\n");
 131         break;
 132     case MBEDTLS_ERR_PK_PASSWORD_MISMATCH:
 133         av_log(h, AV_LOG_ERROR, "The given password for the private key is wrong.\n");
 134         break;
 135     default:
 136         av_log(h, AV_LOG_ERROR, "mbedtls_pk_parse_key returned -0x%x\n", -ret);
 137         break;
 138     }
 139 }
 140
 141 static void handle_handshake_error(URLContext *h, int ret)
 142 {
 143     switch (ret) {
 144 #if MBEDTLS_VERSION_MAJOR < 3
 145     case MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE:
 146         av_log(h, AV_LOG_ERROR, "None of the common ciphersuites is usable. Was the local certificate correctly set?\n");
 147         break;
 148 #else
 149     case MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE:
 150         av_log(h, AV_LOG_ERROR, "TLS handshake failed.\n");
 151         break;
 152     case MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION:
 153         av_log(h, AV_LOG_ERROR, "TLS protocol version mismatch.\n");
 154         break;
 155 #endif
 156     case MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE:
 157         av_log(h, AV_LOG_ERROR, "A fatal alert message was received from the peer, has the peer a correct certificate?\n");
 158         break;
 159     case MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED:
 160         av_log(h, AV_LOG_ERROR, "No CA chain is set, but required to operate. Was the CA correctly set?\n");
 161         break;
 162     case MBEDTLS_ERR_SSL_INTERNAL_ERROR:
 163         av_log(h, AV_LOG_ERROR, "Internal error encountered.\n");
 164         break;
 165     case MBEDTLS_ERR_NET_CONN_RESET:
 166         av_log(h, AV_LOG_ERROR, "TLS handshake was aborted by peer.\n");
 167         break;
 168     case MBEDTLS_ERR_X509_CERT_VERIFY_FAILED:
 169         av_log(h, AV_LOG_ERROR, "Certificate verification failed.\n");
 170         break;
 171     default:
 172         av_log(h, AV_LOG_ERROR, "mbedtls_ssl_handshake returned -0x%x\n", -ret);
 173         break;
 174     }
 175 }
 176
 177 static int tls_open(URLContext *h, const char *uri, int flags, AVDictionary **options)
 178 {
 179     TLSContext *tls_ctx = h->priv_data;
 180     TLSShared *shr = &tls_ctx->tls_shared;
 181     uint32_t verify_res_flags;
 182     int ret;
 183
 184     if ((ret = ff_tls_open_underlying(shr, h, uri, options)) < 0)
 185         goto fail;
 186
 187 #ifdef MBEDTLS_PSA_CRYPTO_C
 188     if ((ret = psa_crypto_init()) != PSA_SUCCESS) {
 189         av_log(h, AV_LOG_ERROR, "psa_crypto_init returned %d\n", ret);
 190         goto fail;
 191     }
 192 #endif
 193
 194     mbedtls_ssl_init(&tls_ctx->ssl_context);
 195     mbedtls_ssl_config_init(&tls_ctx->ssl_config);
 196     mbedtls_entropy_init(&tls_ctx->entropy_context);
 197     mbedtls_ctr_drbg_init(&tls_ctx->ctr_drbg_context);
 198     mbedtls_x509_crt_init(&tls_ctx->ca_cert);
 199     mbedtls_pk_init(&tls_ctx->priv_key);
 200
 201     if (av_log_get_level() >= AV_LOG_DEBUG) {
 202         mbedtls_ssl_conf_dbg(&tls_ctx->ssl_config, mbedtls_debug, shr->tcp);
 203         /*
 204          * Note: we can't call mbedtls_debug_set_threshold() here because
 205          * it's global state. The user is thus expected to manage this.
 206          */
 207     }
 208
 209     // load trusted CA
 210     if (shr->ca_file) {
 211         if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->ca_cert, shr->ca_file)) != 0) {
 212             av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for CA cert returned %d\n", ret);
 213             goto fail;
 214         }
 215     }
 216
 217     // load own certificate
 218     if (shr->cert_file) {
 219         if ((ret = mbedtls_x509_crt_parse_file(&tls_ctx->own_cert, shr->cert_file)) != 0) {
 220             av_log(h, AV_LOG_ERROR, "mbedtls_x509_crt_parse_file for own cert returned %d\n", ret);
 221             goto fail;
 222         }
 223     }
 224
 225     // seed the random number generator
 226     if ((ret = mbedtls_ctr_drbg_seed(&tls_ctx->ctr_drbg_context,
 227                                      mbedtls_entropy_func,
 228                                      &tls_ctx->entropy_context,
 229                                      NULL, 0)) != 0) {
 230         av_log(h, AV_LOG_ERROR, "mbedtls_ctr_drbg_seed returned %d\n", ret);
 231         goto fail;
 232     }
 233
 234     // load key file
 235     if (shr->key_file) {
 236         if ((ret = mbedtls_pk_parse_keyfile(&tls_ctx->priv_key,
 237                                             shr->key_file,
 238                                             tls_ctx->priv_key_pw
 239 #if MBEDTLS_VERSION_MAJOR >= 3
 240                                             , mbedtls_ctr_drbg_random,
 241                                             &tls_ctx->ctr_drbg_context
 242 #endif
 243                                             )) != 0) {
 244             handle_pk_parse_error(h, ret);
 245             goto fail;
 246         }
 247     }
 248
 249     if ((ret = mbedtls_ssl_config_defaults(&tls_ctx->ssl_config,
 250                                            shr->listen ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT,
 251                                            MBEDTLS_SSL_TRANSPORT_STREAM,
 252                                            MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
 253         av_log(h, AV_LOG_ERROR, "mbedtls_ssl_config_defaults returned %d\n", ret);
 254         goto fail;
 255     }
 256
 257 #ifdef MBEDTLS_SSL_PROTO_TLS1_3
 258     // this version does not allow disabling certificate verification with TLSv1.3 (yes, really).
 259     if (mbedtls_version_get_number() == 0x03060000 && !shr->verify) {
 260         av_log(h, AV_LOG_INFO, "Forcing TLSv1.2 because certificate verification is disabled\n");
 261         mbedtls_ssl_conf_max_tls_version(&tls_ctx->ssl_config, MBEDTLS_SSL_VERSION_TLS1_2);
 262     }
 263 #endif
 264
 265     // not VERIFY_REQUIRED because we manually check after handshake
 266     mbedtls_ssl_conf_authmode(&tls_ctx->ssl_config,
 267                               shr->verify ? MBEDTLS_SSL_VERIFY_OPTIONAL : MBEDTLS_SSL_VERIFY_NONE);
 268     mbedtls_ssl_conf_rng(&tls_ctx->ssl_config, mbedtls_ctr_drbg_random, &tls_ctx->ctr_drbg_context);
 269     mbedtls_ssl_conf_ca_chain(&tls_ctx->ssl_config, &tls_ctx->ca_cert, NULL);
 270
 271     // set own certificate and private key
 272     if ((ret = mbedtls_ssl_conf_own_cert(&tls_ctx->ssl_config, &tls_ctx->own_cert, &tls_ctx->priv_key)) != 0) {
 273         av_log(h, AV_LOG_ERROR, "mbedtls_ssl_conf_own_cert returned %d\n", ret);
 274         goto fail;
 275     }
 276
 277     if ((ret = mbedtls_ssl_setup(&tls_ctx->ssl_context, &tls_ctx->ssl_config)) != 0) {
 278         av_log(h, AV_LOG_ERROR, "mbedtls_ssl_setup returned %d\n", ret);
 279         goto fail;
 280     }
 281
 282     if (!shr->listen && !shr->numerichost) {
 283         if ((ret = mbedtls_ssl_set_hostname(&tls_ctx->ssl_context, shr->host)) != 0) {
 284             av_log(h, AV_LOG_ERROR, "mbedtls_ssl_set_hostname returned %d\n", ret);
 285             goto fail;
 286         }
 287     }
 288
 289     // set I/O functions to use FFmpeg internal code for transport layer
 290     mbedtls_ssl_set_bio(&tls_ctx->ssl_context, shr->tcp, mbedtls_send, mbedtls_recv, NULL);
 291
 292     // ssl handshake
 293     while ((ret = mbedtls_ssl_handshake(&tls_ctx->ssl_context)) != 0) {
 294         if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
 295             handle_handshake_error(h, ret);
 296             goto fail;
 297         }
 298     }
 299
 300     if (shr->verify) {
 301         // check the result of the certificate verification
 302         if ((verify_res_flags = mbedtls_ssl_get_verify_result(&tls_ctx->ssl_context)) != 0) {
 303             av_log(h, AV_LOG_ERROR, "mbedtls_ssl_get_verify_result reported problems "\
 304                                     "with the certificate verification, returned flags: %u\n",
 305                                     verify_res_flags);
 306             if (verify_res_flags & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 307                 av_log(h, AV_LOG_ERROR, "The certificate is not correctly signed by the trusted CA.\n");
 308             goto fail;
 309         }
 310     }
 311
 312     return 0;
 313
 314 fail:
 315     tls_close(h);
 316     return AVERROR(EIO);
 317 }
 318
 319 static int handle_tls_error(URLContext *h, const char* func_name, int ret)
 320 {
 321     switch (ret) {
 322     case MBEDTLS_ERR_SSL_WANT_READ:
 323     case MBEDTLS_ERR_SSL_WANT_WRITE:
 324 #ifdef MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET
 325     case MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET:
 326 #endif
 327         return AVERROR(EAGAIN);
 328     case MBEDTLS_ERR_NET_SEND_FAILED:
 329     case MBEDTLS_ERR_NET_RECV_FAILED:
 330         return AVERROR(EIO);
 331     case MBEDTLS_ERR_NET_CONN_RESET:
 332     case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
 333         av_log(h, AV_LOG_WARNING, "%s reported connection reset by peer\n", func_name);
 334         return AVERROR_EOF;
 335     default:
 336         av_log(h, AV_LOG_ERROR, "%s returned -0x%x\n", func_name, -ret);
 337         return AVERROR(EIO);
 338     }
 339 }
 340
 341 static int tls_read(URLContext *h, uint8_t *buf, int size)
 342 {
 343     TLSContext *tls_ctx = h->priv_data;
 344     int ret;
 345
 346     tls_ctx->tls_shared.tcp->flags &= ~AVIO_FLAG_NONBLOCK;
 347     tls_ctx->tls_shared.tcp->flags |= h->flags & AVIO_FLAG_NONBLOCK;
 348     if ((ret = mbedtls_ssl_read(&tls_ctx->ssl_context, buf, size)) > 0) {
 349         // return read length
 350         return ret;
 351     }
 352
 353     return handle_tls_error(h, "mbedtls_ssl_read", ret);
 354 }
 355
 356 static int tls_write(URLContext *h, const uint8_t *buf, int size)
 357 {
 358     TLSContext *tls_ctx = h->priv_data;
 359     int ret;
 360
 361     tls_ctx->tls_shared.tcp->flags &= ~AVIO_FLAG_NONBLOCK;
 362     tls_ctx->tls_shared.tcp->flags |= h->flags & AVIO_FLAG_NONBLOCK;
 363     if ((ret = mbedtls_ssl_write(&tls_ctx->ssl_context, buf, size)) > 0) {
 364         // return written length
 365         return ret;
 366     }
 367
 368     return handle_tls_error(h, "mbedtls_ssl_write", ret);
 369 }
 370
 371 static int tls_get_file_handle(URLContext *h)
 372 {
 373     TLSContext *c = h->priv_data;
 374     return ffurl_get_file_handle(c->tls_shared.tcp);
 375 }
 376
 377 static int tls_get_short_seek(URLContext *h)
 378 {
 379     TLSContext *s = h->priv_data;
 380     return ffurl_get_short_seek(s->tls_shared.tcp);
 381 }
 382
 383 static const AVOption options[] = {
 384     TLS_COMMON_OPTIONS(TLSContext, tls_shared), \
 385     {"key_password", "Password for the private key file", OFFSET(priv_key_pw),  AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
 386     { NULL }
 387 };
 388
 389 static const AVClass tls_class = {
 390     .class_name = "tls",
 391     .item_name  = av_default_item_name,
 392     .option     = options,
 393     .version    = LIBAVUTIL_VERSION_INT,
 394 };
 395
 396 const URLProtocol ff_tls_protocol = {
 397     .name           = "tls",
 398     .url_open2      = tls_open,
 399     .url_read       = tls_read,
 400     .url_write      = tls_write,
 401     .url_close      = tls_close,
 402     .url_get_file_handle = tls_get_file_handle,
 403     .url_get_short_seek  = tls_get_short_seek,
 404     .priv_data_size = sizeof(TLSContext),
 405     .flags          = URL_PROTOCOL_FLAG_NETWORK,
 406     .priv_data_class = &tls_class,
 407 };