From 305c4aa82cb0a400d771fbb79d475b72f9a99977 Mon Sep 17 00:00:00 2001 From: Tobias Brunner Date: Fri, 25 Sep 2015 11:05:24 +0200 Subject: [PATCH] plugin-loader: Optionally use RTLD_NOW with dlopen() This can be useful when writing custom plugins as typos or missing linker flags that result in unresolved symbols in the shared object could otherwise cause late crashes. In particular, if such a symbol is used in a code path that is rarely executed. During development and testing using RTLD_NOW instead of RTLD_LAZY will prevent the plugin from getting loaded and makes the error visible immediately. --- conf/options/charon.opt | 4 ++++ src/libstrongswan/plugins/plugin_loader.c | 17 +++++++++++------ 2 files changed, 15 insertions(+), 6 deletions(-) diff --git a/conf/options/charon.opt b/conf/options/charon.opt index b00fe73b0..808e368b6 100644 --- a/conf/options/charon.opt +++ b/conf/options/charon.opt @@ -65,6 +65,10 @@ charon.dh_exponent_ansi_x9_42 = yes Use ANSI X9.42 DH exponent size or optimum size matched to cryptographic strength. +charon.dlopen_use_rtld_now = no + Use RTLD_NOW with dlopen when loading plugins to reveal missing symbols + immediately. + charon.dns1 DNS server assigned to peer via configuration payload (CP). diff --git a/src/libstrongswan/plugins/plugin_loader.c b/src/libstrongswan/plugins/plugin_loader.c index f7ac347d2..01d0495be 100644 --- a/src/libstrongswan/plugins/plugin_loader.c +++ b/src/libstrongswan/plugins/plugin_loader.c @@ -356,6 +356,7 @@ static plugin_entry_t *load_plugin(private_plugin_loader_t *this, char *name, { plugin_entry_t *entry; void *handle; + int flag = RTLD_LAZY; switch (create_plugin(this, RTLD_DEFAULT, name, FALSE, critical, &entry)) { @@ -380,15 +381,19 @@ static plugin_entry_t *load_plugin(private_plugin_loader_t *this, char *name, return NULL; } } - handle = dlopen(file, RTLD_LAZY + if (lib->settings->get_bool(lib->settings, "%s.dlopen_use_rtld_now", + lib->ns, FALSE)) + { + flag = RTLD_NOW; + } #ifdef RTLD_NODELETE - /* if supported, do not unload library when unloading a plugin. It really - * doesn't matter in productive systems, but causes many (dependency) - * library reloads during unit tests. Some libraries can't handle that, + /* If supported, do not unload the library when unloading a plugin. It + * really doesn't matter in productive systems, but causes many (dependency) + * library reloads during unit tests. Some libraries can't handle that, e.g. * GnuTLS leaks file descriptors in its library load/unload functions. */ - | RTLD_NODELETE + flag |= RTLD_NODELETE; #endif - ); + handle = dlopen(file, flag); if (handle == NULL) { DBG1(DBG_LIB, "plugin '%s' failed to load: %s", name, dlerror());