From ccac55b89443bd9a39f9ec991dc022d300f84b75 Mon Sep 17 00:00:00 2001
From: Sebastian Kemper <sebastian_ml@gmx.net>
Date: Tue, 2 Apr 2019 22:49:52 +0200
Subject: [PATCH] loader: support for permanent dlopen()
Asterisk assumes that dlopen() will always run the constructor of a
shared library and every dlclose() will run its destructor. But dlopen()
may be permanent, meaning the constructor will only be run once, as is
the case with musl libc.
With a permanent dlopen() the Asterisk module loader does not work
correctly, because it's expectations regarding when the constructors and
destructors are run are not met. In fact a segmentation fault will occur
when the first module is "re-opened" that has AST_MODFLAG_GLOBAL_SYMBOLS
set (the dlopen() does not call the constructor, resource_being_loaded
is not set to NULL, then strlen is called with NULL instead of a string,
see issue ASTERISK-28319).
This commit adds code to the loader that will manually run the
constructors/destructors of the (non-builtin) modules where needed. To
achieve this a new ao2 container (linked list) is started and filled
with objects that contain the names of the modules and the pointers to
their respective info structs.
This behavior can be activated when configuring Asterisk
(--enable-permanent-dlopen). By default this is disabled, of course.
ASTERISK-28319 #close
Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>
Change-Id: I86693a0ecf25d5ba81c73773a03df4abc3426875
---
configure | 50 ++++++-----
configure.ac | 14 +++
include/asterisk/autoconfig.h.in | 3 +
main/loader.c | 147 +++++++++++++++++++++++++++++++
4 files changed, 194 insertions(+), 20 deletions(-)
diff --git a/configure b/configure
index d0d60f8e56..2a704b544e 100755
--- a/configure
+++ b/configure
@@ -702,6 +702,7 @@ PBX_DYNAMIC_LIST
POW_LIB
PBX_WORKING_FORK
LIBOBJS
+PERMANENT_DLOPEN
DISABLE_XMLDOC
CONFIG_LIBXML2
JANSSON_LIBS
@@ -1345,7 +1346,6 @@ infodir
docdir
oldincludedir
includedir
-runstatedir
localstatedir
sharedstatedir
sysconfdir
@@ -1454,6 +1454,7 @@ with_vpb
with_x11
with_z
enable_xmldoc
+enable_permanent_dlopen
enable_largefile
enable_internal_poll
enable_asteriskssl
@@ -1533,7 +1534,6 @@ datadir='${datarootdir}'
sysconfdir='${prefix}/etc'
sharedstatedir='${prefix}/com'
localstatedir='${prefix}/var'
-runstatedir='${localstatedir}/run'
includedir='${prefix}/include'
oldincludedir='/usr/include'
docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1786,15 +1786,6 @@ do
| -silent | --silent | --silen | --sile | --sil)
silent=yes ;;
- -runstatedir | --runstatedir | --runstatedi | --runstated \
- | --runstate | --runstat | --runsta | --runst | --runs \
- | --run | --ru | --r)
- ac_prev=runstatedir ;;
- -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
- | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
- | --run=* | --ru=* | --r=*)
- runstatedir=$ac_optarg ;;
-
-sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
ac_prev=sbindir ;;
-sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1932,7 +1923,7 @@ fi
for ac_var in exec_prefix prefix bindir sbindir libexecdir datarootdir \
datadir sysconfdir sharedstatedir localstatedir includedir \
oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
- libdir localedir mandir runstatedir
+ libdir localedir mandir
do
eval ac_val=\$$ac_var
# Remove trailing slashes.
@@ -2085,7 +2076,6 @@ Fine tuning of the installation directories:
--sysconfdir=DIR read-only single-machine data [PREFIX/etc]
--sharedstatedir=DIR modifiable architecture-independent data [PREFIX/com]
--localstatedir=DIR modifiable single-machine data [PREFIX/var]
- --runstatedir=DIR modifiable per-process data [LOCALSTATEDIR/run]
--libdir=DIR object code libraries [EPREFIX/lib]
--includedir=DIR C header files [PREFIX/include]
--oldincludedir=DIR C header files for non-gcc [/usr/include]
@@ -2124,6 +2114,9 @@ Optional Features:
--enable-dev-mode Turn on developer mode
--enable-coverage Turn on code coverage tracking (for gcov)
--disable-xmldoc Explicitly disable XML documentation
+ --enable-permanent-dlopen
+ Enable when your libc has a permanent dlopen like
+ musl
--disable-largefile omit support for large files
--enable-internal-poll Use Asterisk's poll implementation
--disable-asteriskssl Disable Asterisk's SSL wrapper library
@@ -14852,6 +14845,25 @@ fi
+fi
+
+# Check whether --enable-permanent-dlopen was given.
+if test "${enable_permanent_dlopen+set}" = set; then :
+ enableval=$enable_permanent_dlopen; case "${enableval}" in
+ y|ye|yes) PERMANENT_DLOPEN=yes ;;
+ n|no) PERMANENT_DLOPEN=no ;;
+ *) as_fn_error $? "bad value ${enableval} for --enable-permanent-dlopen" "$LINENO" 5 ;;
+ esac
+else
+ PERMANENT_DLOPEN=no
+fi
+
+
+
+if test "${PERMANENT_DLOPEN}" == "yes"; then
+
+$as_echo "#define HAVE_PERMANENT_DLOPEN 1" >>confdefs.h
+
fi
# some embedded systems omit internationalization (locale) support
@@ -14918,7 +14930,7 @@ else
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
&& LARGE_OFF_T % 2147483647 == 1)
? 1 : -1];
@@ -14964,7 +14976,7 @@ else
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
&& LARGE_OFF_T % 2147483647 == 1)
? 1 : -1];
@@ -14988,7 +15000,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
&& LARGE_OFF_T % 2147483647 == 1)
? 1 : -1];
@@ -15033,7 +15045,7 @@ else
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
&& LARGE_OFF_T % 2147483647 == 1)
? 1 : -1];
@@ -15057,7 +15069,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
We can't simply define LARGE_OFF_T to be 9223372036854775807,
since some C++ compilers masquerading as C compilers
incorrectly reject 9223372036854775807. */
-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
&& LARGE_OFF_T % 2147483647 == 1)
? 1 : -1];
@@ -16357,8 +16369,6 @@ main ()
if (*(data + i) != *(data3 + i))
return 14;
close (fd);
- free (data);
- free (data3);
return 0;
}
_ACEOF
diff --git a/configure.ac b/configure.ac
index 1ec7765058..e65f159803 100644
--- a/configure.ac
+++ b/configure.ac
@@ -729,6 +729,20 @@ if test "${DISABLE_XMLDOC}" != "yes"; then
fi
+AC_ARG_ENABLE([permanent-dlopen],
+ [AS_HELP_STRING([--enable-permanent-dlopen],
+ [Enable when your libc has a permanent dlopen like musl])],
+ [case "${enableval}" in
+ y|ye|yes) PERMANENT_DLOPEN=yes ;;
+ n|no) PERMANENT_DLOPEN=no ;;
+ *) AC_MSG_ERROR(bad value ${enableval} for --enable-permanent-dlopen) ;;
+ esac], [PERMANENT_DLOPEN=no])
+
+AC_SUBST([PERMANENT_DLOPEN])
+if test "${PERMANENT_DLOPEN}" == "yes"; then
+ AC_DEFINE([HAVE_PERMANENT_DLOPEN], 1, [Define to support libc with permanent dlopen.])
+fi
+
# some embedded systems omit internationalization (locale) support
AC_CHECK_HEADERS([xlocale.h])
diff --git a/include/asterisk/autoconfig.h.in b/include/asterisk/autoconfig.h.in
index 46e92dfb56..71df798c12 100644
--- a/include/asterisk/autoconfig.h.in
+++ b/include/asterisk/autoconfig.h.in
@@ -603,6 +603,9 @@
/* Define to 1 if your system defines the file flag O_SYMLINK in fcntl.h */
#undef HAVE_O_SYMLINK
+/* Define to support libc with permanent dlopen. */
+#undef HAVE_PERMANENT_DLOPEN
+
/* Define to indicate the PostgreSQL library */
#undef HAVE_PGSQL
diff --git a/main/loader.c b/main/loader.c
index 3749c95993..b46f745af8 100644
--- a/main/loader.c
+++ b/main/loader.c
@@ -153,6 +153,117 @@ static unsigned int loader_ready;
static struct ast_vector_string startup_errors;
static struct ast_str *startup_error_builder;
+#if defined(HAVE_PERMANENT_DLOPEN)
+#define FIRST_DLOPEN 999
+
+struct ao2_container *info_list = NULL;
+
+struct info_list_obj {
+ const struct ast_module_info *info;
+ int dlopened;
+ char name[0];
+};
+
+static struct info_list_obj *info_list_obj_alloc(const char *name,
+ const struct ast_module_info *info)
+{
+ struct info_list_obj *new_entry;
+
+ new_entry = ao2_alloc(sizeof(*new_entry) + strlen(name) + 1, NULL);
+
+ if (!new_entry) {
+ return NULL;
+ }
+
+ strcpy(new_entry->name, name); /* SAFE */
+ new_entry->info = info;
+ new_entry->dlopened = FIRST_DLOPEN;
+
+ return new_entry;
+}
+
+AO2_STRING_FIELD_CMP_FN(info_list_obj, name)
+
+static char *get_name_from_resource(const char *resource)
+{
+ int len;
+ const char *last_three;
+ char *mod_name;
+
+ if (!resource) {
+ return NULL;
+ }
+
+ len = strlen(resource);
+ if (len > 3) {
+ last_three = &resource[len-3];
+ if (!strcasecmp(last_three, ".so")) {
+ mod_name = ast_calloc(1, len - 2);
+ if (mod_name) {
+ ast_copy_string(mod_name, resource, len - 2);
+ return mod_name;
+ } else {
+ /* Unable to allocate memory. */
+ return NULL;
+ }
+ }
+ }
+
+ /* Resource is the name - happens when manually unloading a module. */
+ mod_name = ast_calloc(1, len + 1);
+ if (mod_name) {
+ ast_copy_string(mod_name, resource, len + 1);
+ return mod_name;
+ }
+
+ /* Unable to allocate memory. */
+ return NULL;
+}
+
+static void manual_mod_reg(const void *lib, const char *resource)
+{
+ struct info_list_obj *obj_tmp;
+ char *mod_name;
+
+ if (lib) {
+ mod_name = get_name_from_resource(resource);
+ if (mod_name) {
+ obj_tmp = ao2_find(info_list, mod_name, OBJ_SEARCH_KEY);
+ if (obj_tmp) {
+ if (obj_tmp->dlopened == FIRST_DLOPEN) {
+ obj_tmp->dlopened = 1;
+ } else {
+ ast_module_register(obj_tmp->info);
+ }
+ ao2_ref(obj_tmp, -1);
+ }
+ ast_free(mod_name);
+ }
+ }
+}
+
+static void manual_mod_unreg(const char *resource)
+{
+ struct info_list_obj *obj_tmp;
+ char *mod_name;
+
+ /* When Asterisk shuts down the destructor is called automatically. */
+ if (ast_shutdown_final()) {
+ return;
+ }
+
+ mod_name = get_name_from_resource(resource);
+ if (mod_name) {
+ obj_tmp = ao2_find(info_list, mod_name, OBJ_SEARCH_KEY);
+ if (obj_tmp) {
+ ast_module_unregister(obj_tmp->info);
+ ao2_ref(obj_tmp, -1);
+ }
+ ast_free(mod_name);
+ }
+}
+#endif
+
static __attribute__((format(printf, 1, 2))) void module_load_error(const char *fmt, ...)
{
char *copy = NULL;
@@ -597,6 +708,23 @@ void ast_module_register(const struct ast_module_info *info)
/* give the module a copy of its own handle, for later use in registrations and the like */
*((struct ast_module **) &(info->self)) = mod;
+
+#if defined(HAVE_PERMANENT_DLOPEN)
+ if (mod->flags.builtin != 1) {
+ struct info_list_obj *obj_tmp = ao2_find(info_list, info->name,
+ OBJ_SEARCH_KEY);
+
+ if (!obj_tmp) {
+ obj_tmp = info_list_obj_alloc(info->name, info);
+ if (obj_tmp) {
+ ao2_link(info_list, obj_tmp);
+ ao2_ref(obj_tmp, -1);
+ }
+ } else {
+ ao2_ref(obj_tmp, -1);
+ }
+ }
+#endif
}
static int module_post_register(struct ast_module *mod)
@@ -843,6 +971,10 @@ static void logged_dlclose(const char *name, void *lib)
error = dlerror();
ast_log(AST_LOG_ERROR, "Failure in dlclose for module '%s': %s\n",
S_OR(name, "unknown"), S_OR(error, "Unknown error"));
+#if defined(HAVE_PERMANENT_DLOPEN)
+ } else {
+ manual_mod_unreg(name);
+#endif
}
}
@@ -949,6 +1081,9 @@ static struct ast_module *load_dlopen(const char *resource_in, const char *so_ex
resource_being_loaded = mod;
mod->lib = dlopen(filename, flags);
+#if defined(HAVE_PERMANENT_DLOPEN)
+ manual_mod_reg(mod->lib, mod->resource);
+#endif
if (resource_being_loaded) {
struct ast_str *list;
int c = 0;
@@ -968,6 +1103,9 @@ static struct ast_module *load_dlopen(const char *resource_in, const char *so_ex
resource_being_loaded = mod;
mod->lib = dlopen(filename, RTLD_LAZY | RTLD_LOCAL);
+#if defined(HAVE_PERMANENT_DLOPEN)
+ manual_mod_reg(mod->lib, mod->resource);
+#endif
if (resource_being_loaded) {
resource_being_loaded = NULL;
@@ -2206,6 +2344,15 @@ int load_modules(void)
ast_verb(1, "Asterisk Dynamic Loader Starting:\n");
+#if defined(HAVE_PERMANENT_DLOPEN)
+ info_list = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, NULL,
+ info_list_obj_cmp_fn); /* must not be cleaned at shutdown */
+ if (!info_list) {
+ fprintf(stderr, "Module info list allocation failure.\n");
+ return 1;
+ }
+#endif
+
AST_LIST_HEAD_INIT_NOLOCK(&load_order);
AST_DLLIST_LOCK(&module_list);
--
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