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RFC 9266: Channel Bindings for TLS 1.3 #4191 #4772

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RFC 9266: Channel Bindings for TLS 1.3 #4191 #4772

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48 changes: 38 additions & 10 deletions imap/tls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1314,19 +1314,47 @@ EXPORTED int tls_start_servertls(int readfd, int writefd, int timeout,
saslprops->ssf = (sasl_ssf_t) tls_cipher_usebits;

#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL)
if (SSL_session_reused(tls_conn)) {
saslprops->cbinding.len = SSL_get_finished(tls_conn,
saslprops->tls_finished,
MAX_FINISHED_LEN);
if (SSL_version(tls_conn) <= TLS1_2_VERSION) {
if (SSL_session_reused(tls_conn)) {
saslprops->cbinding.len =
SSL_get_finished(tls_conn,
saslprops->tls_finished,
MAX_FINISHED_LEN);
}
else {
saslprops->cbinding.len =
SSL_get_peer_finished(tls_conn,
saslprops->tls_finished,
MAX_FINISHED_LEN);
}
saslprops->cbinding.name = "tls-unique";
saslprops->cbinding.data = saslprops->tls_finished;
}
#if (OPENSSL_VERSION_NUMBER >= 0x10100001L)
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else {
/* see RFC 9266 Section 2, Definition of label, context, length */
static const char label[] = "EXPORTER-Channel-Binding";
static const size_t key_len = 32;

assert(key_len <= sizeof(saslprops->tls_finished));
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if (1 != SSL_export_keying_material(tls_conn,
saslprops->tls_finished, key_len,
label, sizeof(label)-1,
0, 0, 0)) {
syslog(LOG_ERR, "Error reading EKM for channel binding");
}
else {
saslprops->cbinding.name = "tls-exporter";
saslprops->cbinding.data = saslprops->tls_finished;
saslprops->cbinding.len = key_len;
}
}
#else
else {
saslprops->cbinding.len = SSL_get_peer_finished(tls_conn,
saslprops->tls_finished,
MAX_FINISHED_LEN);
/* This case should not happen. It's a strange OpenSSL variant */
syslog(LOG_ERR, "No EKM (channel binding) for TLS 1.3 or higher");
}

saslprops->cbinding.name = "tls-unique";
saslprops->cbinding.data = saslprops->tls_finished;
#endif /* (OPENSSL_VERSION_NUMBER >= 0x10100001L) */
#endif /* (OPENSSL_VERSION_NUMBER >= 0x0090800fL) */

#if OPENSSL_VERSION_NUMBER >= 0x10002000L
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44 changes: 35 additions & 9 deletions imtest/imtest.c
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Original file line number Diff line number Diff line change
Expand Up @@ -791,20 +791,46 @@ static void do_starttls(int ssl, char *keyfile, unsigned *ssf)
imtest_fatal("Error setting SASL property (external auth_id)");

#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL)
static unsigned char finished[EVP_MAX_MD_SIZE];
static struct sasl_channel_binding cbinding;

if (SSL_session_reused(tls_conn)) {
cbinding.len = SSL_get_peer_finished(tls_conn,
finished, sizeof(finished));
if (SSL_version(tls_conn) <= TLS1_2_VERSION) {
static unsigned char finished[EVP_MAX_MD_SIZE];

if (SSL_session_reused(tls_conn)) {
cbinding.len =
SSL_get_peer_finished(tls_conn, finished, sizeof(finished));
}
else {
cbinding.len =
SSL_get_finished(tls_conn, finished, sizeof(finished));
}

cbinding.name = "tls-unique";
cbinding.critical = 0;
cbinding.data = finished;
}
#if (OPENSSL_VERSION_NUMBER >= 0x10100001L)
else {
cbinding.len = SSL_get_finished(tls_conn, finished, sizeof(finished));
}
/* see RFC 9266 Section 2, Definition of label, context, length */
static const char label[] = "EXPORTER-Channel-Binding";
static unsigned char exported_key[32];
static const size_t key_len = sizeof(exported_key);

cbinding.name = "tls-unique";
cbinding.critical = 0;
cbinding.data = finished;
if (1 != SSL_export_keying_material(tls_conn, exported_key, key_len,
label, sizeof(label)-1, 0, 0, 0)) {
imtest_fatal("Error reading EKM for channel binding");
}
cbinding.name = "tls-exporter";
cbinding.critical = 0;
cbinding.len = key_len;
cbinding.data = exported_key;
}
#else
else {
/* This case should not happen. It's a strange OpenSSL variant */
imtest_fatal("No EKM (channel binding) for TLS 1.3 or higher");
}
#endif /* (OPENSSL_VERSION_NUMBER >= 0x10100001L) */

result = sasl_setprop(conn, SASL_CHANNEL_BINDING, &cbinding);
if (result!=SASL_OK)
Expand Down