From 1bdda52fe92fd01b424cd6fbb63e3df96a95015c Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Fri, 29 Nov 2019 10:44:59 -0300 Subject: elf: Move vDSO setup to rtld (BZ#24967) 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 --- sysdeps/generic/dl-vdso.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 sysdeps/generic/dl-vdso.h (limited to 'sysdeps/generic/dl-vdso.h') diff --git a/sysdeps/generic/dl-vdso.h b/sysdeps/generic/dl-vdso.h new file mode 100644 index 0000000000..70379a82a1 --- /dev/null +++ b/sysdeps/generic/dl-vdso.h @@ -0,0 +1,30 @@ +/* ELF symbol resolve functions for VDSO objects. + Copyright (C) 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 + . */ + +#ifndef _DL_VDSO_H +#define _DL_VDSO_H 1 + +/* Function for resolving symbols in the VDSO link map. Return the + address of the vdso symbol NAME. */ +static inline void * +dl_vdso_vsym (const char *name) +{ + return NULL; +} + +#endif -- cgit 1.4.1