MEDIUM: ssl: increase default-dh-param to 2048

For 6 years now we've been seeing a warning suggesting to set dh-param
beyond 1024 if possible when it was not set. It's about time to do it
and get rid of this warning since most users seem to already use 2048.
It will remain possible to set a lower value of course, so only those
who were experiencing the warning and were relying on the default value
may notice a change (higher CPU usage). For more context, please refer
to this thread :

  https://www.mail-archive.com/haproxy@formilux.org/msg37226.html

This commit removes a big chunk of code which happened to be needed
exclusively to figure if it was required to emit a warning or not :-)

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 40dae3fd74d518a6586861b547a2daa3ee1a40c4..0d4e295a2cc5f820bbaae97b67a4e7fad1b95fc2 100644 (file)
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -2125,7 +2125,7 @@ tune.ssl.default-dh-param <number>
   the ephemeral/temporary Diffie-Hellman key in case of DHE key exchange. The
   final size will try to match the size of the server's RSA (or DSA) key (e.g,
   a 2048 bits temporary DH key for a 2048 bits RSA key), but will not exceed
-  this maximum value. Default value if 1024. Only 1024 or higher values are
+  this maximum value. Default value if 2048. Only 1024 or higher values are
   allowed. Higher values will increase the CPU load, and values greater than
   1024 bits are not supported by Java 7 and earlier clients. This value is not
   used if static Diffie-Hellman parameters are supplied either directly

diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 8b02a1d662144b3ab047ba4f88b72ad0a94dbfff..78d6da303aee23ad89fc1beb5efe02250d367efe 100644 (file)
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -5615,46 +5615,8 @@ int ssl_sock_prepare_ctx(struct bind_conf *bind_conf, struct ssl_bind_conf *ssl_
            global_dh == NULL &&
            (ssl_dh_ptr_index == -1 ||
             SSL_CTX_get_ex_data(ctx, ssl_dh_ptr_index) == NULL)) {
-               STACK_OF(SSL_CIPHER) * ciphers = NULL;
-               const SSL_CIPHER * cipher = NULL;
-               char cipher_description[128];
-               /* The description of ciphers using an Ephemeral Diffie Hellman key exchange
-                  contains " Kx=DH " or " Kx=DH(". Beware of " Kx=DH/",
-                  which is not ephemeral DH. */
-               const char dhe_description[] = " Kx=DH ";
-               const char dhe_export_description[] = " Kx=DH(";
-               int idx = 0;
-               int dhe_found = 0;
-               SSL *ssl = NULL;
-
-               ssl = SSL_new(ctx);
-
-               if (ssl) {
-                       ciphers = SSL_get_ciphers(ssl);
-
-                       if (ciphers) {
-                               for (idx = 0; idx < sk_SSL_CIPHER_num(ciphers); idx++) {
-                                       cipher = sk_SSL_CIPHER_value(ciphers, idx);
-                                       if (SSL_CIPHER_description(cipher, cipher_description, sizeof (cipher_description)) == cipher_description) {
-                                               if (strstr(cipher_description, dhe_description) != NULL ||
-                                                   strstr(cipher_description, dhe_export_description) != NULL) {
-                                                       dhe_found = 1;
-                                                       break;
-                                               }
-                                       }
-                               }
-                       }
-                       SSL_free(ssl);
-                       ssl = NULL;
-               }
-
-               if (dhe_found) {
-                       memprintf(err, "%sSetting tune.ssl.default-dh-param to 1024 by default, if your workload permits it you should set it to at least 2048. Please set a value >= 1024 to make this warning disappear.\n",
-                                 err && *err ? *err : "");
-                       cfgerr |= ERR_WARN;
-               }
-
-               global_ssl.default_dh_param = 1024;
+               /* default to dh-param 2048 */
+               global_ssl.default_dh_param = 2048;
        }
 
        if (global_ssl.default_dh_param >= 1024) {