GLRO (_rtld_global_ro) is read-only after initialization and can
therefore not be patched at run time, unlike the hook table addresses
and their contents, so this is a desirable hardening feature.
The hooks are only needed if ld.so has not been initialized, and this
happens only after static dlopen (dlmopen uses a single ld.so object
across all namespaces).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2004-10-18 Jakub Jelinek <jakub@redhat.com>
* elf/dl-libc.c (__libc_dlsym_private, __libc_register_dl_open_hook):
New functions.
(__libc_dlopen_mode): Call __libc_register_dl_open_hook and
__libc_register_dlfcn_hook.
* dlfcn/Makefile (routines, elide-routines.os): Set.
Add rules to build and test tststatic2.
* dlfcn/tststatic2.c: New test.
* dlfcn/modstatic2.c: New test module.
* dlfcn/dladdr.c: Call _dlfcn_hook from libdl.so if not NULL.
Define __ prefixed routine in libc.a and in libdl.a just call it.
* dlfcn/dladdr1.c: Likewise.
* dlfcn/dlclose.c: Likewise.
* dlfcn/dlerror.c: Likewise.
* dlfcn/dlinfo.c: Likewise.
* dlfcn/dlmopen.c: Likewise.
* dlfcn/dlopen.c: Likewise.
* dlfcn/dlopenold.c: Likewise.
* dlfcn/dlsym.c: Likewise.
* dlfcn/dlvsym.c: Likewise.
* dlfcn/sdladdr.c: New file.
* dlfcn/sdladdr1.c: New file.
* dlfcn/sdlclose.c: New file.
* dlfcn/sdlerror.c: New file.
* dlfcn/sdlinfo.c: New file.
* dlfcn/sdlopen.c: New file.
* dlfcn/sdlsym.c: New file.
* dlfcn/sdlvsym.c: New file.
* dlfcn/Versions (libdl): Export _dlfcn_hook@GLIBC_PRIVATE.
* include/dlfcn.h (DL_CALLER_DECL, DL_CALLER RETURN_ADDRESS): Define.
(struct dlfcn_hook): New type.
(_dlfcn_hook): New extern decl.
(__dlopen, __dlclose, __dlsym, __dlerror, __dladdr, __dladdr1,
__dlinfo, __dlmopen, __libc_dlsym_private,
__libc_register_dl_open_hook, __libc_register_dlfcn_hook): New
prototypes.
(__dlvsym): Use DL_CALLER_DECL.
* include/libc-symbols.h: Define libdl_hidden_proto and friends.
* malloc/arena.c (_dl_open_hook): Extern decl.
(ptmalloc_init): Don't call _dl_addr when dlopened from statically
linked programs but don't use brk for them either.
