From 78b31cc8341ab8268c468cd0f4f988d1d7862a55 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 17 May 2021 09:59:14 +0200 Subject: elf: Partially initialize ld.so after static dlopen (bug 20802) After static dlopen, a copy of ld.so is loaded into the inner namespace, but that copy is not initialized at all. Some architectures run into serious problems as result, which is why the _dl_var_init mechanism was invented. With libpthread moving into libc and parts into ld.so, more architectures impacted, so it makes sense to switch to a generic mechanism which performs the partial initialization. As a result, getauxval now works after static dlopen (bug 20802). Reviewed-by: Adhemerval Zanella --- elf/rtld_static_init.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 elf/rtld_static_init.c (limited to 'elf/rtld_static_init.c') diff --git a/elf/rtld_static_init.c b/elf/rtld_static_init.c new file mode 100644 index 0000000000..cd823096d6 --- /dev/null +++ b/elf/rtld_static_init.c @@ -0,0 +1,56 @@ +/* Partial initialization of ld.so loaded via static dlopen. + Copyright (C) 2021 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 + . */ + +#include + +/* Very special case: This object is built into the static libc, but + must know the layout of _rtld_global_ro. */ +#define SHARED +#include + +#include + +void +__rtld_static_init (struct link_map *map) +{ + const ElfW(Sym) *sym + = _dl_lookup_direct (map, "_rtld_global_ro", + 0x9f28436a, /* dl_new_hash output. */ + "GLIBC_PRIVATE", + 0x0963cf85); /* _dl_elf_hash output. */ + assert (sym != NULL); + struct rtld_global_ro *dl = DL_SYMBOL_ADDRESS (map, sym); + + /* Perform partial initialization here. Note that this runs before + ld.so is relocated, so only members initialized without + relocations can be written here. */ +#ifdef HAVE_AUX_VECTOR + extern __typeof (dl->_dl_auxv) _dl_auxv attribute_hidden; + dl->_dl_auxv = _dl_auxv; + extern __typeof (dl->_dl_clktck) _dl_clktck attribute_hidden; + dl->_dl_clktck = _dl_clktck; +#endif + extern __typeof (dl->_dl_hwcap) _dl_hwcap attribute_hidden; + dl->_dl_hwcap = _dl_hwcap; + extern __typeof (dl->_dl_hwcap2) _dl_hwcap2 attribute_hidden; + dl->_dl_hwcap2 = _dl_hwcap2; + extern __typeof (dl->_dl_pagesize) _dl_pagesize attribute_hidden; + dl->_dl_pagesize = _dl_pagesize; + + __rtld_static_init_arch (map, dl); +} -- cgit 1.4.1