+/*************************************************
+* Expand key and cert file specs *
+*************************************************/
+
+/* Called once during tls_init and possibly againt during TLS setup, for a
+new context, if Server Name Indication was used and tls_sni was seen in
+the certificate string.
+
+Arguments:
+ sctx the SSL_CTX* to update
+ cbinfo various parts of session state
+
+Returns: OK/DEFER/FAIL
+*/
+
+static int
+tls_expand_session_files(SSL_CTX *sctx, const tls_ext_ctx_cb *cbinfo)
+{
+uschar *expanded;
+
+if (cbinfo->certificate == NULL)
+ return OK;
+
+if (Ustrstr(cbinfo->certificate, US"tls_sni"))
+ reexpand_tls_files_for_sni = TRUE;
+
+if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
+ return DEFER;
+
+if (expanded != NULL)
+ {
+ DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
+ if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
+ return tls_error(string_sprintf(
+ "SSL_CTX_use_certificate_chain_file file=%s", expanded),
+ cbinfo->host, NULL);
+ }
+
+if (cbinfo->privatekey != NULL &&
+ !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
+ return DEFER;
+
+/* If expansion was forced to fail, key_expanded will be NULL. If the result
+of the expansion is an empty string, ignore it also, and assume the private
+key is in the same file as the certificate. */
+
+if (expanded != NULL && *expanded != 0)
+ {
+ DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
+ if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
+ return tls_error(string_sprintf(
+ "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
+ }
+
+return OK;
+}
+
+
+
+
+/*************************************************
+* Callback to handle SNI *
+*************************************************/
+
+/* Called when acting as server during the TLS session setup if a Server Name
+Indication extension was sent by the client.
+
+API documentation is OpenSSL s_server.c implementation.
+
+Arguments:
+ s SSL* of the current session
+ ad unknown (part of OpenSSL API) (unused)
+ arg Callback of "our" registered data
+
+Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
+*/
+
+static int
+tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
+/* pre-declared for SSL_CTX_set_tlsext_servername_callback call within func */
+
+static int
+tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
+{
+const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
+const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
+int rc;
+
+if (!servername)
+ return SSL_TLSEXT_ERR_OK;
+
+DEBUG(D_tls) debug_printf("TLS SNI: %s%s\n", servername,
+ reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
+
+/* Make the extension value available for expansion */
+tls_sni = servername;
+
+if (!reexpand_tls_files_for_sni)
+ return SSL_TLSEXT_ERR_OK;
+
+/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
+not confident that memcpy wouldn't break some internal reference counting.
+Especially since there's a references struct member, which would be off. */
+
+ctx_sni = SSL_CTX_new(SSLv23_server_method());
+if (!ctx_sni)
+ {
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
+ return SSL_TLSEXT_ERR_NOACK;
+ }
+
+/* Not sure how many of these are actually needed, since SSL object
+already exists. Might even need this selfsame callback, for reneg? */
+
+SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx));
+SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx));
+SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx));
+SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx));
+SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb);
+SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo);
+if (cbinfo->server_cipher_list)
+ SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list);
+
+rc = tls_expand_session_files(ctx_sni, cbinfo);
+if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
+
+rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE);
+if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
+
+DEBUG(D_tls) debug_printf("Switching SSL context.\n");
+SSL_set_SSL_CTX(s, ctx_sni);
+
+return SSL_TLSEXT_ERR_OK;
+}
+
+
+
+
git://git.exim.org / exim.git / commitdiff