ffmpeg/libavformat/tls_mbedtls.c

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/*
* 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/certs.h>
#include <mbedtls/config.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 "avformat.h"
#include "internal.h"
#include "url.h"
#include "tls.h"
#include "libavutil/parseutils.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);
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 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) {
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;
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_NET_CONN_RESET:
av_log(h, AV_LOG_ERROR, "TLS handshake was aborted by peer.\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;
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);
// 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;
}
}
// 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)) != 0) {
handle_pk_parse_error(h, 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;
}
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;
}
mbedtls_ssl_conf_authmode(&tls_ctx->ssl_config,
shr->ca_file ? MBEDTLS_SSL_VERIFY_REQUIRED : 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:
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;
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;
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 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,
.priv_data_size = sizeof(TLSContext),
.flags = URL_PROTOCOL_FLAG_NETWORK,
.priv_data_class = &tls_class,
};