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SSL: enabled TLSv1.3 with BoringSSL.

BoringSSL currently requires SSL_CTX_set_max_proto_version(TLS1_3_VERSION)
to be able to enable TLS 1.3.  This is because by default max protocol
version is set to TLS 1.2, and the SSL_OP_NO_* options are merely used
as a blacklist within the version range specified using the
SSL_CTX_set_min_proto_version() and SSL_CTX_set_max_proto_version()
functions.

With this change, we now call SSL_CTX_set_max_proto_version() with an
explicit maximum version set.  This enables TLS 1.3 with BoringSSL.
As a side effect, this change also limits maximum protocol version to
the newest protocol we know about, TLS 1.3.  This seems to be a good
change, as enabling unknown protocols might have unexpected results.

Additionally, we now explicitly call SSL_CTX_set_min_proto_version()
with 0.  This is expected to help with Debian system-wide default
of MinProtocol set to TLSv1.2, see
http://mailman.nginx.org/pipermail/nginx-ru/2017-October/060411.html.

Note that there is no SSL_CTX_set_min_proto_version macro in BoringSSL,
so we call SSL_CTX_set_min_proto_version() and SSL_CTX_set_max_proto_version()
as long as the TLS1_3_VERSION macro is defined.
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mdounin committed Aug 6, 2018
1 parent a6baf5e commit 9f30fda1c2e24058e91a8c637c0717b32be399da
Showing with 5 additions and 0 deletions.
  1. +5 −0 src/event/ngx_event_openssl.c
@@ -331,6 +331,11 @@ ngx_ssl_create(ngx_ssl_t *ssl, ngx_uint_t protocols, void *data)
}
#endif
#ifdef TLS1_3_VERSION
SSL_CTX_set_min_proto_version(ssl->ctx, 0);
SSL_CTX_set_max_proto_version(ssl->ctx, TLS1_3_VERSION);
#endif
#ifdef SSL_OP_NO_COMPRESSION
SSL_CTX_set_options(ssl->ctx, SSL_OP_NO_COMPRESSION);
#endif

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