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res_rtp_asterisk: Use separate SRTP session for RTCP with DTLS

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Asterisk uses separate UDP ports for RTP and RTCP traffic and RFC 5764
explicitly states:

  There MUST be a separate DTLS-SRTP session for each distinct pair of
  source and destination ports used by a media session

This means RTP keying material cannot be used for DTLS RTCP, which was
the reason why RTCP encryption would fail.

ASTERISK-25642

Change-Id: I7e8779d8b63e371088081bb113131361b2847e3a
changes/92/2492/1
Jacek Konieczny 10 years ago committed by Joshua Colp
parent 6ce25bd62a
commit 970803efcb
4 changed files with 42 additions and 22 deletions
Show Stats Download Patch File Download Diff File

6
include/asterisk/rtp_engine.h
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@ -2228,20 +2228,22 @@ int ast_rtp_instance_sendcng(struct ast_rtp_instance *instance, int level);
* \param instance the RTP instance * \param instance the RTP instance
* \param remote_policy the remote endpoint's policy * \param remote_policy the remote endpoint's policy
* \param local_policy our policy for this RTP instance's remote endpoint * \param local_policy our policy for this RTP instance's remote endpoint
* \param rtcp 1 for dedicated RTCP policies
* *
* \retval 0 Success * \retval 0 Success
* \retval non-zero Failure * \retval non-zero Failure
*/ */
int ast_rtp_instance_add_srtp_policy(struct ast_rtp_instance *instance, struct ast_srtp_policy* remote_policy, struct ast_srtp_policy *local_policy); int ast_rtp_instance_add_srtp_policy(struct ast_rtp_instance *instance, struct ast_srtp_policy* remote_policy, struct ast_srtp_policy *local_policy, int rtcp);
/*! /*!
* \brief Obtain the SRTP instance associated with an RTP instance * \brief Obtain the SRTP instance associated with an RTP instance
* *
* \param instance the RTP instance * \param instance the RTP instance
* \param rtcp 1 to request instance for RTCP
* \retval the SRTP instance on success * \retval the SRTP instance on success
* \retval NULL if no SRTP instance exists * \retval NULL if no SRTP instance exists
*/ */
struct ast_srtp *ast_rtp_instance_get_srtp(struct ast_rtp_instance *instance); struct ast_srtp *ast_rtp_instance_get_srtp(struct ast_rtp_instance *instance, int rtcp);
/*! \brief Custom formats declared in codecs.conf at startup must be communicated to the rtp_engine /*! \brief Custom formats declared in codecs.conf at startup must be communicated to the rtp_engine
* so their mime type can payload number can be initialized. */ * so their mime type can payload number can be initialized. */

27
main/rtp_engine.c
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@ -188,6 +188,8 @@ struct ast_rtp_instance {
struct ast_rtp_glue *glue; struct ast_rtp_glue *glue;
/*! SRTP info associated with the instance */ /*! SRTP info associated with the instance */
struct ast_srtp *srtp; struct ast_srtp *srtp;
/*! SRTP info dedicated for RTCP associated with the instance */
struct ast_srtp *rtcp_srtp;
/*! Channel unique ID */ /*! Channel unique ID */
char channel_uniqueid[AST_MAX_UNIQUEID]; char channel_uniqueid[AST_MAX_UNIQUEID];
/*! Time of last packet sent */ /*! Time of last packet sent */
@ -364,6 +366,10 @@ static void instance_destructor(void *obj)
res_srtp->destroy(instance->srtp); res_srtp->destroy(instance->srtp);
} }
if (instance->rtcp_srtp) {
res_srtp->destroy(instance->rtcp_srtp);
}
ast_rtp_codecs_payloads_destroy(&instance->codecs); ast_rtp_codecs_payloads_destroy(&instance->codecs);
/* Drop our engine reference */ /* Drop our engine reference */
@ -2052,29 +2058,38 @@ int ast_rtp_engine_srtp_is_registered(void)
return res_srtp && res_srtp_policy; return res_srtp && res_srtp_policy;
} }
int ast_rtp_instance_add_srtp_policy(struct ast_rtp_instance *instance, struct ast_srtp_policy *remote_policy, struct ast_srtp_policy *local_policy) int ast_rtp_instance_add_srtp_policy(struct ast_rtp_instance *instance, struct ast_srtp_policy *remote_policy, struct ast_srtp_policy *local_policy, int rtcp)
{ {
int res = 0; int res = 0;
struct ast_srtp **srtp;
if (!res_srtp) { if (!res_srtp) {
return -1; return -1;
} }
if (!instance->srtp) {
res = res_srtp->create(&instance->srtp, instance, remote_policy); srtp = rtcp ? &instance->rtcp_srtp : &instance->srtp;
if (!*srtp) {
res = res_srtp->create(srtp, instance, remote_policy);
} else { } else {
res = res_srtp->replace(&instance->srtp, instance, remote_policy); res = res_srtp->replace(srtp, instance, remote_policy);
} }
if (!res) { if (!res) {
res = res_srtp->add_stream(instance->srtp, local_policy); res = res_srtp->add_stream(*srtp, local_policy);
} }
return res; return res;
} }
struct ast_srtp *ast_rtp_instance_get_srtp(struct ast_rtp_instance *instance) struct ast_srtp *ast_rtp_instance_get_srtp(struct ast_rtp_instance *instance, int rtcp)
{ {
if (rtcp && instance->rtcp_srtp) {
return instance->rtcp_srtp;
}
else {
return instance->srtp; return instance->srtp;
}
} }
int ast_rtp_instance_sendcng(struct ast_rtp_instance *instance, int level) int ast_rtp_instance_sendcng(struct ast_rtp_instance *instance, int level)

2
main/sdp_srtp.c
Unescape View File

@ -183,7 +183,7 @@ static int crypto_activate(struct ast_sdp_crypto *p, int suite_val, unsigned cha
} }
/* Add the SRTP policies */ /* Add the SRTP policies */
if (ast_rtp_instance_add_srtp_policy(rtp, remote_policy, local_policy)) { if (ast_rtp_instance_add_srtp_policy(rtp, remote_policy, local_policy, 0)) {
ast_log(LOG_WARNING, "Could not set SRTP policies\n"); ast_log(LOG_WARNING, "Could not set SRTP policies\n");
goto err; goto err;
} }

25
res/res_rtp_asterisk.c
Unescape View File

@ -1982,19 +1982,20 @@ static int dtls_srtp_renegotiate(const void *data)
return 0; return 0;
} }
static int dtls_srtp_setup(struct ast_rtp *rtp, struct ast_srtp *srtp, struct ast_rtp_instance *instance) static int dtls_srtp_setup(struct ast_rtp *rtp, struct ast_srtp *srtp, struct ast_rtp_instance *instance, int rtcp)
{ {
unsigned char material[SRTP_MASTER_LEN * 2]; unsigned char material[SRTP_MASTER_LEN * 2];
unsigned char *local_key, *local_salt, *remote_key, *remote_salt; unsigned char *local_key, *local_salt, *remote_key, *remote_salt;
struct ast_srtp_policy *local_policy, *remote_policy = NULL; struct ast_srtp_policy *local_policy, *remote_policy = NULL;
struct ast_rtp_instance_stats stats = { 0, }; struct ast_rtp_instance_stats stats = { 0, };
int res = -1; int res = -1;
struct dtls_details *dtls = !rtcp ? &rtp->dtls : &rtp->rtcp->dtls;
/* If a fingerprint is present in the SDP make sure that the peer certificate matches it */ /* If a fingerprint is present in the SDP make sure that the peer certificate matches it */
if (rtp->dtls_verify & AST_RTP_DTLS_VERIFY_FINGERPRINT) { if (rtp->dtls_verify & AST_RTP_DTLS_VERIFY_FINGERPRINT) {
X509 *certificate; X509 *certificate;
if (!(certificate = SSL_get_peer_certificate(rtp->dtls.ssl))) { if (!(certificate = SSL_get_peer_certificate(dtls->ssl))) {
ast_log(LOG_WARNING, "No certificate was provided by the peer on RTP instance '%p'\n", instance); ast_log(LOG_WARNING, "No certificate was provided by the peer on RTP instance '%p'\n", instance);
return -1; return -1;
} }
@ -2028,14 +2029,14 @@ static int dtls_srtp_setup(struct ast_rtp *rtp, struct ast_srtp *srtp, struct as
} }
/* Ensure that certificate verification was successful */ /* Ensure that certificate verification was successful */
if ((rtp->dtls_verify & AST_RTP_DTLS_VERIFY_CERTIFICATE) && SSL_get_verify_result(rtp->dtls.ssl) != X509_V_OK) { if ((rtp->dtls_verify & AST_RTP_DTLS_VERIFY_CERTIFICATE) && SSL_get_verify_result(dtls->ssl) != X509_V_OK) {
ast_log(LOG_WARNING, "Peer certificate on RTP instance '%p' failed verification test\n", ast_log(LOG_WARNING, "Peer certificate on RTP instance '%p' failed verification test\n",
instance); instance);
return -1; return -1;
} }
/* Produce key information and set up SRTP */ /* Produce key information and set up SRTP */
if (!SSL_export_keying_material(rtp->dtls.ssl, material, SRTP_MASTER_LEN * 2, "EXTRACTOR-dtls_srtp", 19, NULL, 0, 0)) { if (!SSL_export_keying_material(dtls->ssl, material, SRTP_MASTER_LEN * 2, "EXTRACTOR-dtls_srtp", 19, NULL, 0, 0)) {
ast_log(LOG_WARNING, "Unable to extract SRTP keying material from DTLS-SRTP negotiation on RTP instance '%p'\n", ast_log(LOG_WARNING, "Unable to extract SRTP keying material from DTLS-SRTP negotiation on RTP instance '%p'\n",
instance); instance);
return -1; return -1;
@ -2090,7 +2091,7 @@ static int dtls_srtp_setup(struct ast_rtp *rtp, struct ast_srtp *srtp, struct as
res_srtp_policy->set_ssrc(remote_policy, 0, 1); res_srtp_policy->set_ssrc(remote_policy, 0, 1);
if (ast_rtp_instance_add_srtp_policy(instance, remote_policy, local_policy)) { if (ast_rtp_instance_add_srtp_policy(instance, remote_policy, local_policy, rtcp)) {
ast_log(LOG_WARNING, "Could not set policies when setting up DTLS-SRTP on '%p'\n", rtp); ast_log(LOG_WARNING, "Could not set policies when setting up DTLS-SRTP on '%p'\n", rtp);
goto error; goto error;
} }
@ -2121,7 +2122,7 @@ static int __rtp_recvfrom(struct ast_rtp_instance *instance, void *buf, size_t s
{ {
int len; int len;
struct ast_rtp *rtp = ast_rtp_instance_get_data(instance); struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance); struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance, rtcp);
char *in = buf; char *in = buf;
#ifdef HAVE_PJPROJECT #ifdef HAVE_PJPROJECT
struct ast_sockaddr *loop = rtcp ? &rtp->rtcp_loop : &rtp->rtp_loop; struct ast_sockaddr *loop = rtcp ? &rtp->rtcp_loop : &rtp->rtp_loop;
@ -2178,10 +2179,8 @@ static int __rtp_recvfrom(struct ast_rtp_instance *instance, void *buf, size_t s
if (SSL_is_init_finished(dtls->ssl)) { if (SSL_is_init_finished(dtls->ssl)) {
/* Any further connections will be existing since this is now established */ /* Any further connections will be existing since this is now established */
dtls->connection = AST_RTP_DTLS_CONNECTION_EXISTING; dtls->connection = AST_RTP_DTLS_CONNECTION_EXISTING;
if (!rtcp) {
/* Use the keying material to set up key/salt information */ /* Use the keying material to set up key/salt information */
res = dtls_srtp_setup(rtp, srtp, instance); res = dtls_srtp_setup(rtp, srtp, instance, rtcp);
}
} else { } else {
/* Since we've sent additional traffic start the timeout timer for retransmission */ /* Since we've sent additional traffic start the timeout timer for retransmission */
dtls_srtp_start_timeout_timer(instance, rtp, rtcp); dtls_srtp_start_timeout_timer(instance, rtp, rtcp);
@ -2250,7 +2249,7 @@ static int __rtp_sendto(struct ast_rtp_instance *instance, void *buf, size_t siz
int len = size; int len = size;
void *temp = buf; void *temp = buf;
struct ast_rtp *rtp = ast_rtp_instance_get_data(instance); struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance); struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance, rtcp);
int res; int res;
*ice = 0; *ice = 0;
@ -2950,7 +2949,8 @@ static void ast_rtp_update_source(struct ast_rtp_instance *instance)
static void ast_rtp_change_source(struct ast_rtp_instance *instance) static void ast_rtp_change_source(struct ast_rtp_instance *instance)
{ {
struct ast_rtp *rtp = ast_rtp_instance_get_data(instance); struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance); struct ast_srtp *srtp = ast_rtp_instance_get_srtp(instance, 0);
struct ast_srtp *rtcp_srtp = ast_rtp_instance_get_srtp(instance, 1);
unsigned int ssrc = ast_random(); unsigned int ssrc = ast_random();
if (!rtp->lastts) { if (!rtp->lastts) {
@ -2966,6 +2966,9 @@ static void ast_rtp_change_source(struct ast_rtp_instance *instance)
if (srtp) { if (srtp) {
ast_debug(3, "Changing ssrc for SRTP from %u to %u\n", rtp->ssrc, ssrc); ast_debug(3, "Changing ssrc for SRTP from %u to %u\n", rtp->ssrc, ssrc);
res_srtp->change_source(srtp, rtp->ssrc, ssrc); res_srtp->change_source(srtp, rtp->ssrc, ssrc);
if (rtcp_srtp != srtp) {
res_srtp->change_source(srtp, rtp->ssrc, ssrc);
}
} }
rtp->ssrc = ssrc; rtp->ssrc = ssrc;

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