mod_ssl: Log private key material to file set by $SSLKEYLOGFILE in the

environment, using the standard format which can be parsed by (e.g.)
wireshark for decoding SSL/TLS traffic; supported from OpenSSL 1.1.1.

* modules/ssl/ssl_private.h: Add keylog_file to SSLModConfigRec.

* modules/ssl/ssl_engine_init.c (ssl_init_Module): Open log file if
  SSLKEYLOGFILE is set in the environment.
  (ssl_init_ctx_protocol): Register the keylog callback with OpenSSL.

* modules/ssl/ssl_engine_kernel.c (modssl_callback_keylog):
  New function.

PR: 63391
Github: closes #74


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1869842 13f79535-47bb-0310-9956-ffa450edef68

CHANGES

@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.1
-   
+
+  *) mod_ssl: Support logging private key material for use with
+     wireshark via log file given by SSLKEYLOGFILE environment
+     variable.  Requires OpenSSL 1.1.1.  PR 63391.  [Joe Orton]
+
   *) mod_proxy: Improve tunneling loop to support half closed connections and
      pending data draining (for protocols like rsync). PR 61616. [Yann Ylavic]
 

docs/log-message-tags/next-number

@@ -1 +1 @@
-10226
+10228

modules/ssl/ssl_engine_config.c

@@ -79,6 +79,10 @@ SSLModConfigRec *ssl_config_global_create(server_rec *s)
     mc->stapling_refresh_mutex = NULL;
 #endif
 
+#ifdef HAVE_OPENSSL_KEYLOG
+    mc->keylog_file = NULL;
+#endif
+
     apr_pool_userdata_set(mc, SSL_MOD_CONFIG_KEY,
                           apr_pool_cleanup_null,
                           pool);

modules/ssl/ssl_engine_init.c

@@ -440,6 +440,28 @@ apr_status_t ssl_init_Module(apr_pool_t *p, apr_pool_t *plog,
     init_bio_methods();
 #endif
 
+#ifdef HAVE_OPENSSL_KEYLOG
+    {
+        const char *logfn = getenv("SSLKEYLOGFILE");
+
+        if (logfn) {
+            rv = apr_file_open(&mc->keylog_file, logfn,
+                               APR_FOPEN_CREATE|APR_FOPEN_WRITE|APR_FOPEN_APPEND|APR_FOPEN_LARGEFILE,
+                               APR_FPROT_UREAD|APR_FPROT_UWRITE,
+                               mc->pPool);
+            if (rv) {
+                ap_log_error(APLOG_MARK, APLOG_NOTICE, rv, s, APLOGNO(10226)
+                             "Could not open log file '%s' configured via SSLKEYLOGFILE",
+                             logfn);
+                return rv;
+            }
+
+            ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, s, APLOGNO(10227)
+                         "Init: Logging SSL private key material to %s", logfn);
+        }
+    }
+#endif
+    
     return OK;
 }
 
@@ -826,6 +848,12 @@ static apr_status_t ssl_init_ctx_protocol(server_rec *s,
      * https://github.com/openssl/openssl/issues/7178 */
     SSL_CTX_clear_mode(ctx, SSL_MODE_AUTO_RETRY);
 #endif
+
+#ifdef HAVE_OPENSSL_KEYLOG
+    if (mctx->sc->mc->keylog_file) {
+        SSL_CTX_set_keylog_callback(ctx, modssl_callback_keylog);
+    }
+#endif
     
     return APR_SUCCESS;
 }

modules/ssl/ssl_engine_kernel.c

@@ -2803,3 +2803,17 @@ int ssl_callback_SRPServerParams(SSL *ssl, int *ad, void *arg)
 }
 
 #endif /* HAVE_SRP */
+
+
+#ifdef HAVE_OPENSSL_KEYLOG
+/* Callback used with SSL_CTX_set_keylog_callback. */
+void modssl_callback_keylog(const SSL *ssl, const char *line)
+{
+    conn_rec *conn = SSL_get_app_data(ssl);
+    SSLSrvConfigRec *sc = mySrvConfig(conn->base_server);
+
+    if (sc && sc->mc->keylog_file) {
+        apr_file_printf(sc->mc->keylog_file, "%s\n", line);
+    }
+}
+#endif

modules/ssl/ssl_private.h

@@ -250,6 +250,10 @@ void free_bio_methods(void);
 #endif
 #endif
 
+#if OPENSSL_VERSION_NUMBER >= 0x10101000L && !defined(LIBRESSL_VERSION_NUMBER)
+#define HAVE_OPENSSL_KEYLOG
+#endif
+
 /* mod_ssl headers */
 #include "ssl_util_ssl.h"
 
@@ -603,6 +607,10 @@ typedef struct {
     apr_global_mutex_t   *stapling_refresh_mutex;
 #endif
 
+#ifdef HAVE_OPENSSL_KEYLOG
+    /* Used for logging if SSLKEYLOGFILE is set at startup. */
+    apr_file_t      *keylog_file;
+#endif
 } SSLModConfigRec;
 
 /** Structure representing configured filenames for certs and keys for
@@ -963,6 +971,11 @@ int          ssl_stapling_init_cert(server_rec *, apr_pool_t *, apr_pool_t *,
 int          ssl_callback_SRPServerParams(SSL *, int *, void *);
 #endif
 
+#ifdef HAVE_OPENSSL_KEYLOG
+/* Callback used with SSL_CTX_set_keylog_callback. */
+void         modssl_callback_keylog(const SSL *ssl, const char *line);
+#endif
+
 /**  I/O  */
 void         ssl_io_filter_init(conn_rec *, request_rec *r, SSL *);
 void         ssl_io_filter_register(apr_pool_t *);