web/SOURCES/httpd-2.4.6-ssl-large-keys.patch

diff --git a/modules/ssl/ssl_engine_init.c b/modules/ssl/ssl_engine_init.c
index 46769e9..0275452 100644
--- a/modules/ssl/ssl_engine_init.c
+++ b/modules/ssl/ssl_engine_init.c
@@ -41,6 +41,79 @@
 #define KEYTYPES "RSA or DSA"
 #endif
 
+/*
+ * Grab well-defined DH parameters from OpenSSL, see the get_rfc*
+ * functions in <openssl/bn.h> for all available primes.
+ */
+static DH *make_dh_params(BIGNUM *(*prime)(BIGNUM *), const char *gen)
+{
+    DH *dh = DH_new();
+
+    if (!dh) {
+        return NULL;
+    }
+    dh->p = prime(NULL);
+    BN_dec2bn(&dh->g, gen);
+    if (!dh->p || !dh->g) {
+        DH_free(dh);
+        return NULL;
+    }
+    return dh;
+}
+
+/* Storage and initialization for DH parameters. */
+static struct dhparam {
+    BIGNUM *(*const prime)(BIGNUM *); /* function to generate... */
+    DH *dh;                           /* ...this, used for keys.... */
+    const unsigned int min;           /* ...of length >= this. */
+} dhparams[] = {
+    { get_rfc3526_prime_8192, NULL, 6145 },
+    { get_rfc3526_prime_6144, NULL, 4097 },
+    { get_rfc3526_prime_4096, NULL, 3073 },
+    { get_rfc3526_prime_3072, NULL, 2049 },
+    { get_rfc3526_prime_2048, NULL, 1025 },
+    { get_rfc2409_prime_1024, NULL, 0 }
+};
+
+static void init_dh_params(void)
+{
+    unsigned n;
+
+    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++)
+        dhparams[n].dh = make_dh_params(dhparams[n].prime, "2");
+}
+
+static void free_dh_params(void)
+{
+    unsigned n;
+
+    /* DH_free() is a noop for a NULL parameter, so these are harmless
+     * in the (unexpected) case where these variables are already
+     * NULL. */
+    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++) {
+        DH_free(dhparams[n].dh);
+        dhparams[n].dh = NULL;
+    }
+}
+
+/* Hand out the same DH structure though once generated as we leak
+ * memory otherwise and freeing the structure up after use would be
+ * hard to track and in fact is not needed at all as it is safe to
+ * use the same parameters over and over again security wise (in
+ * contrast to the keys itself) and code safe as the returned structure
+ * is duplicated by OpenSSL anyway. Hence no modification happens
+ * to our copy. */
+DH *modssl_get_dh_params(unsigned keylen)
+{
+    unsigned n;
+
+    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++)
+        if (keylen >= dhparams[n].min)
+            return dhparams[n].dh;
+        
+    return NULL; /* impossible to reach. */
+}
+
 static void ssl_add_version_components(apr_pool_t *p,
                                        server_rec *s)
 {
@@ -244,6 +317,8 @@ int ssl_init_Module(apr_pool_t *p, apr_pool_t *plog,
 
     SSL_init_app_data2_idx(); /* for SSL_get_app_data2() at request time */
 
+    init_dh_params();
+
     return OK;
 }
 
@@ -1623,6 +1698,8 @@ apr_status_t ssl_init_ModuleKill(void *data)
         ssl_init_ctx_cleanup_server(sc->server);
     }
 
+    free_dh_params();
+
     return APR_SUCCESS;
 }
 
diff --git a/modules/ssl/ssl_engine_kernel.c b/modules/ssl/ssl_engine_kernel.c
index 2d6d59e..1ecbccd 100644
--- a/modules/ssl/ssl_engine_kernel.c
+++ b/modules/ssl/ssl_engine_kernel.c
@@ -1287,34 +1287,6 @@ const authz_provider ssl_authz_provider_verify_client =
 */
 
 /*
- * Grab well-defined DH parameters from OpenSSL, see <openssl/bn.h>
- * (get_rfc*) for all available primes.
- */
-#define make_get_dh(rfc,size,gen) \
-static DH *get_dh##size(void) \
-{ \
-    DH *dh; \
-    if (!(dh = DH_new())) { \
-        return NULL; \
-    } \
-    dh->p = get_##rfc##_prime_##size(NULL); \
-    BN_dec2bn(&dh->g, #gen); \
-    if (!dh->p || !dh->g) { \
-        DH_free(dh); \
-        return NULL; \
-    } \
-    return dh; \
-}
-
-/*
- * Prepare DH parameters from 1024 to 4096 bits, in 1024-bit increments
- */
-make_get_dh(rfc2409, 1024, 2)
-make_get_dh(rfc3526, 2048, 2)
-make_get_dh(rfc3526, 3072, 2)
-make_get_dh(rfc3526, 4096, 2)
-
-/*
  * Hand out standard DH parameters, based on the authentication strength
  */
 DH *ssl_callback_TmpDH(SSL *ssl, int export, int keylen)
@@ -1342,14 +1314,7 @@ DH *ssl_callback_TmpDH(SSL *ssl, int export, int keylen)
     ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c,
                   "handing out built-in DH parameters for %d-bit authenticated connection", keylen);
 
-    if (keylen >= 4096)
-        return get_dh4096();
-    else if (keylen >= 3072)
-        return get_dh3072();
-    else if (keylen >= 2048)
-        return get_dh2048();
-    else
-        return get_dh1024();
+    return modssl_get_dh_params(keylen);
 }
 
 /*
diff --git a/modules/ssl/ssl_private.h b/modules/ssl/ssl_private.h
index 744af9e..f47ed47 100644
--- a/modules/ssl/ssl_private.h
+++ b/modules/ssl/ssl_private.h
@@ -990,6 +990,11 @@ OCSP_RESPONSE *modssl_dispatch_ocsp_request(const apr_uri_t *uri,
                                             conn_rec *c, apr_pool_t *p);
 #endif
 
+/* Retrieve DH parameters for given key length.  Return value should
+ * be treated as unmutable, since it is stored in process-global
+ * memory. */
+DH *modssl_get_dh_params(unsigned keylen);
+
 #endif /* SSL_PRIVATE_H */
 /** @} */