glibc/dlfcn/dlopen.c
Florian Weimer 8dcb6d0af0 dlfcn: Do not use rtld_active () to determine ld.so state (bug 29078)
When audit modules are loaded, ld.so initialization is not yet
complete, and rtld_active () returns false even though ld.so is
mostly working.  Instead, the static dlopen hook is used, but that
does not work at all because this is not a static dlopen situation.

Commit 466c1ea15f ("dlfcn: Rework
static dlopen hooks") moved the hook pointer into _rtld_global_ro,
which means that separate protection is not needed anymore and the
hook pointer can be checked directly.

The guard for disabling libio vtable hardening in _IO_vtable_check
should stay for now.

Fixes commit 8e1472d2c1 ("ld.so:
Examine GLRO to detect inactive loader [BZ #20204]").

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-04-26 14:24:36 +02:00

104 lines
2.8 KiB
C

/* Load a shared object at run time.
Copyright (C) 1995-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dlfcn.h>
#include <libintl.h>
#include <stddef.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <shlib-compat.h>
struct dlopen_args
{
/* The arguments for dlopen_doit. */
const char *file;
int mode;
/* The return value of dlopen_doit. */
void *new;
/* Address of the caller. */
const void *caller;
};
/* Non-shared code has no support for multiple namespaces. */
#ifdef SHARED
# define NS __LM_ID_CALLER
#else
# define NS LM_ID_BASE
#endif
static void
dlopen_doit (void *a)
{
struct dlopen_args *args = (struct dlopen_args *) a;
if (args->mode & ~(RTLD_BINDING_MASK | RTLD_NOLOAD | RTLD_DEEPBIND
| RTLD_GLOBAL | RTLD_LOCAL | RTLD_NODELETE
| __RTLD_SPROF))
_dl_signal_error (0, NULL, NULL, _("invalid mode parameter"));
args->new = GLRO(dl_open) (args->file ?: "", args->mode | __RTLD_DLOPEN,
args->caller,
args->file == NULL ? LM_ID_BASE : NS,
__libc_argc, __libc_argv, __environ);
}
static void *
dlopen_implementation (const char *file, int mode, void *dl_caller)
{
struct dlopen_args args;
args.file = file;
args.mode = mode;
args.caller = dl_caller;
return _dlerror_run (dlopen_doit, &args) ? NULL : args.new;
}
#ifdef SHARED
void *
___dlopen (const char *file, int mode)
{
if (GLRO (dl_dlfcn_hook) != NULL)
return GLRO (dl_dlfcn_hook)->dlopen (file, mode, RETURN_ADDRESS (0));
else
return dlopen_implementation (file, mode, RETURN_ADDRESS (0));
}
versioned_symbol (libc, ___dlopen, dlopen, GLIBC_2_34);
# if OTHER_SHLIB_COMPAT (libdl, GLIBC_2_1, GLIBC_2_34)
compat_symbol (libdl, ___dlopen, dlopen, GLIBC_2_1);
# endif
#else /* !SHARED */
/* Also used with _dlfcn_hook. */
void *
__dlopen (const char *file, int mode, void *dl_caller)
{
return dlopen_implementation (file, mode, RETURN_ADDRESS (0));
}
void *
___dlopen (const char *file, int mode)
{
return __dlopen (file, mode, RETURN_ADDRESS (0));
}
weak_alias (___dlopen, dlopen)
static_link_warning (dlopen)
#endif /* !SHARED */