mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-05 03:01:05 +00:00
1bdda52fe9
This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/* ELF symbol resolve functions for VDSO objects.
|
|
Copyright (C) 2005-2020 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/>. */
|
|
|
|
#ifndef _DL_VDSO_H
|
|
#define _DL_VDSO_H 1
|
|
|
|
#include <ldsodefs.h>
|
|
#include <dl-hash.h>
|
|
|
|
/* If the architecture support vDSO it should define which is the expected
|
|
kernel version and hash value through both VDSO_NAME and VDSO_HASH
|
|
(usually defined at architecture sysdep.h). */
|
|
|
|
#ifndef VDSO_NAME
|
|
# define VDSO_NAME "LINUX_0.0"
|
|
#endif
|
|
#ifndef VDSO_HASH
|
|
# define VDSO_HASH 0
|
|
#endif
|
|
|
|
/* Functions for resolving symbols in the VDSO link map. */
|
|
static inline void *
|
|
dl_vdso_vsym (const char *name)
|
|
{
|
|
struct link_map *map = GLRO (dl_sysinfo_map);
|
|
if (map == NULL)
|
|
return NULL;
|
|
|
|
/* Use a WEAK REF so we don't error out if the symbol is not found. */
|
|
ElfW (Sym) wsym = { 0 };
|
|
wsym.st_info = (unsigned char) ELFW (ST_INFO (STB_WEAK, STT_NOTYPE));
|
|
|
|
struct r_found_version rfv = { VDSO_NAME, VDSO_HASH, 1, NULL };
|
|
|
|
/* Search the scope of the vdso map. */
|
|
const ElfW (Sym) *ref = &wsym;
|
|
lookup_t result = GLRO (dl_lookup_symbol_x) (name, map, &ref,
|
|
map->l_local_scope,
|
|
&rfv, 0, 0, NULL);
|
|
return ref != NULL ? DL_SYMBOL_ADDRESS (result, ref) : NULL;
|
|
}
|
|
|
|
#endif /* dl-vdso.h */
|