I've installed
grep PRETTY /etc/os-release
PRETTY_NAME="Fedora 32 (Server Edition)"
dovecot --version
2.3.10.1 (a3d0e1171)
openssl version
OpenSSL 1.1.1g FIPS 21 Apr 2020
iiuc, Dovecot has apparently had support for setting TLS 1.3 ciphersuites since
v2.3.9, per this commit
lib-ssl-iostream: Support TLSv1.3 ciphersuites
https://github.com/dovecot/core/commit/8f6f04eb21276f28b81695dd0d3df57c7b8f43e4
checking openssl
rpm -ql openssl-devel-1.1.1g-1.fc32.x86_64 | grep -i ciphersuites
/usr/share/man/man3/SSL_CTX_set_ciphersuites.3ssl.gz
/usr/share/man/man3/SSL_set_ciphersuites.3ssl.gz
man SSL_set_ciphersuites
...
SSL_set_cipher_list() sets the list of ciphers (TLSv1.2 and
below) only for ssl.
SSL_CTX_set_ciphersuites() is used to configure the available
TLSv1.3 ciphersuites for ctx. This is a simple colon
(":") separated list of TLSv1.3 ciphersuite names in order of
preference. Valid TLSv1.3 ciphersuite names are:
TLS_AES_128_GCM_SHA256
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_CCM_SHA256
TLS_AES_128_CCM_8_SHA256
An empty list is permissible. The default value for the this
setting is:
"TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256"
SSL_set_ciphersuites() is the same as
SSL_CTX_set_ciphersuites() except it configures the ciphersuites for ssl.
...
checkin in dovecot tag 2.3.10.1's src,
m4/ssl.m4 (m4)
...
AC_CHECK_LIB(ssl, SSL_CTX_set_ciphersuites, [
AC_DEFINE(HAVE_SSL_CTX_SET_CIPHERSUITES,, [Build with
SSL_CTX_set_ciphersuites() support])
],, $SSL_LIBS)
...
and,
src/lib-ssl-iostream/iostream-openssl.c
...
#ifdef HAVE_SSL_CTX_SET_CIPHERSUITES
if (set->ciphersuites != NULL &&
strcmp(ctx_set->ciphersuites,
set->ciphersuites) != 0) {
if (SSL_set_ciphersuitesl(ssl_io->ssl,
set->ciphersuites) == 0) {
*error_r = t_strdup_printf(
"Can't set ciphersuites to
'%s': %s",
set->ciphersuites,
openssl_iostream_error());
return -1;
}
}
#endif
...
suggests that ciphersuite support exists.
bug, checking in
./src/lib-master/master-service-ssl.c
...
void master_service_ssl_ctx_init(struct master_service *service)
{
const struct master_service_ssl_settings *set;
struct ssl_iostream_settings ssl_set;
const char *error;
if (service->ssl_ctx_initialized)
return;
service->ssl_ctx_initialized = TRUE;
/* must be called after master_service_init_finish() so
that if
initialization fails we can close the SSL listeners */
i_assert(service->listeners != NULL ||
service->socket_count == 0);
set = master_service_ssl_settings_get(service);
if (strcmp(set->ssl, "no") == 0) {
/* SSL disabled, don't use it */
return;
}
i_zero(&ssl_set);
ssl_set.min_protocol = set->ssl_min_protocol;
ssl_set.cipher_list = set->ssl_cipher_list;
ssl_set.curve_list = set->ssl_curve_list;
ssl_set.ca = set->ssl_ca;
...
there's only mention of
set->ssl_cipher_list
, not
set->ssl_ciphersuites
or equivalent, afaict.
if in dovecot's 10-ssl.conf I set
ssl_cipher_list =
ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256
+ ssl_ciphersuites =
TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256
on restart
journalctl -f -u dovecot
-- Logs begin at Sun 2020-09-20 14:30:30 PDT. --
Sep 23 18:28:42 mx.example.com dovecot[4269]: doveconf: Fatal:
Error in configuration file /etc/dovecot/conf.d/10-ssl.conf line 92: Unknown
setting: ssl_ciphersuites
_is_ setting TLS 1.3
ssl_ciphersuites =
in fact currently supported, and usage is wrong here^?
