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elf: Move vDSO setup to rtld (BZ#24967)

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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>
This commit is contained in:
Adhemerval Zanella
2019-11-29 10:44:59 -03:00
parent 57013650f7
commit 1bdda52fe9
31 changed files with 258 additions and 290 deletions
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1
sysdeps/unix/sysv/linux/powerpc/Makefile
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@ -13,7 +13,6 @@ gen-as-const-headers += ucontext_i.sym
endif
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
ifeq ($(build-shared),yes)
# This is needed for DSO loading from static binaries.
sysdep-dl-routines += dl-static

5
sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
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@ -21,7 +21,7 @@
#include <libc-internal.h>
#include <not-cancel.h>
#include <libc-vdso.h>
#include <sysdep-vdso.h>
static uint64_t
get_timebase_freq_fallback (void)
@ -101,8 +101,7 @@ uint64_t
__get_timebase_freq (void)
{
/* The vDSO does not have a fallback mechanism (such calling a syscall). */
__typeof (VDSO_SYMBOL (get_tbfreq)) vdsop = VDSO_SYMBOL (get_tbfreq);
PTR_DEMANGLE (vdsop);
uint64_t (*vdsop)(void) = GLRO(dl_vdso_get_tbfreq);
if (vdsop == NULL)
return get_timebase_freq_fallback ();

50
sysdeps/unix/sysv/linux/powerpc/init-first.c
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@ -1,50 +0,0 @@
/* Initialization code run first thing by the ELF startup code. Linux/PowerPC.
Copyright (C) 2007-2020 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/>. */
#include <dl-vdso.h>
#include <libc-vdso.h>
unsigned long long (*VDSO_SYMBOL(get_tbfreq)) (void) attribute_hidden;
#if defined(__PPC64__) || defined(__powerpc64__)
void *VDSO_SYMBOL(sigtramp_rt64) attribute_hidden;
#else
void *VDSO_SYMBOL(sigtramp32) attribute_hidden;
void *VDSO_SYMBOL(sigtramp_rt32) attribute_hidden;
#endif
static inline void
__libc_vdso_platform_setup_arch (void)
{
VDSO_SYMBOL (get_tbfreq) = get_vdso_mangle_symbol (HAVE_GET_TBFREQ);
/* PPC64 uses only one signal trampoline symbol, while PPC32 will use
two depending if SA_SIGINFO is used (__kernel_sigtramp_rt32) or not
(__kernel_sigtramp32).
There is no need to pointer mangle these symbol because they will
used only for pointer comparison. */
#if defined(__PPC64__) || defined(__powerpc64__)
VDSO_SYMBOL(sigtramp_rt64) = get_vdso_symbol (HAVE_SIGTRAMP_RT64);
#else
VDSO_SYMBOL(sigtramp32) = get_vdso_symbol (HAVE_SIGTRAMP_32);
VDSO_SYMBOL(sigtramp_rt32) = get_vdso_symbol (HAVE_SIGTRAMP_RT32);
#endif
}
#define VDSO_SETUP_ARCH __libc_vdso_platform_setup_arch
#include <sysdeps/unix/sysv/linux/init-first.c>

10
sysdeps/unix/sysv/linux/powerpc/libc-vdso.h
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@ -54,14 +54,4 @@
# define VDSO_IFUNC_RET(value) ((void *) (value))
#endif
#include_next <libc-vdso.h>
extern unsigned long long (*VDSO_SYMBOL(get_tbfreq)) (void);
#if defined(__PPC64__) || defined(__powerpc64__)
extern void *VDSO_SYMBOL(sigtramp_rt64);
#else
extern void *VDSO_SYMBOL(sigtramp32);
extern void *VDSO_SYMBOL(sigtramp_rt32);
#endif
#endif /* _LIBC_VDSO_H */