From 8ec4de7501d9ea340a950107c56513cced9bc97e Mon Sep 17 00:00:00 2001 From: Sebastian Kemper 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 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 d8e1cbf..bb3244d 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 @@ -1337,7 +1338,6 @@ infodir docdir oldincludedir includedir -runstatedir localstatedir sharedstatedir sysconfdir @@ -1446,6 +1446,7 @@ with_vpb with_x11 with_z enable_xmldoc +enable_permanent_dlopen enable_largefile enable_internal_poll enable_asteriskssl @@ -1525,7 +1526,6 @@ 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}' @@ -1778,15 +1778,6 @@ 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=$ac_optarg ;; - -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb) ac_prev=sbindir ;; -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \ @@ -1924,7 +1915,7 @@ fi for ac_var in exec_prefix prefix bindir sbindir libexecdir datarootdir \ datadir sysconfdir sharedstatedir localstatedir includedir \ oldincludedir docdir infodir htmldir dvidir pdfdir psdir \ - libdir localedir mandir runstatedir + libdir localedir mandir do eval ac_val=\$$ac_var # Remove trailing slashes. @@ -2077,7 +2068,6 @@ 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] @@ -2116,6 +2106,9 @@ 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 @@ -14816,6 +14809,25 @@ 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 for ac_header in xlocale.h do : @@ -14880,7 +14892,7 @@ 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]; @@ -14926,7 +14938,7 @@ 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]; @@ -14950,7 +14962,7 @@ 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]; @@ -14995,7 +15007,7 @@ 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]; @@ -15019,7 +15031,7 @@ 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]; @@ -16319,8 +16331,6 @@ 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 7acfcbc..3c64307 100644 --- a/configure.ac +++ b/configure.ac @@ -727,6 +727,20 @@ 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 72f6ee0..9de15e5 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 3749c95..b46f745 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); -- 1.7.9.5