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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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55
sysdeps/unix/sysv/linux/dl-vdso-setup.h Normal file
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@ -0,0 +1,55 @@
/* ELF symbol initialization functions for VDSO objects. Linux version.
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
<https://www.gnu.org/licenses/>. */
#ifndef _DL_VDSO_INIT_H
#define _DL_VDSO_INIT_H
/* Initialize the VDSO functions pointers. */
static inline void __attribute__ ((always_inline))
setup_vdso_pointers (void)
{
#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
GLRO(dl_vdso_clock_gettime) = dl_vdso_vsym (HAVE_CLOCK_GETTIME_VSYSCALL);
#endif
#ifdef HAVE_GETTIMEOFDAY_VSYSCALL
GLRO(dl_vdso_gettimeofday) = dl_vdso_vsym (HAVE_GETTIMEOFDAY_VSYSCALL);
#endif
#ifdef HAVE_TIME_VSYSCALL
GLRO(dl_vdso_time) = dl_vdso_vsym (HAVE_TIME_VSYSCALL);
#endif
#ifdef HAVE_GETCPU_VSYSCALL
GLRO(dl_vdso_getcpu) = dl_vdso_vsym (HAVE_GETCPU_VSYSCALL);
#endif
#ifdef HAVE_CLOCK_GETRES_VSYSCALL
GLRO(dl_vdso_clock_getres) = dl_vdso_vsym (HAVE_CLOCK_GETRES_VSYSCALL);
#endif
#ifdef HAVE_GET_TBFREQ
GLRO(dl_vdso_get_tbfreq) = dl_vdso_vsym (HAVE_GET_TBFREQ);
#endif
#ifdef HAVE_SIGTRAMP_RT64
GLRO(dl_vdso_sigtramp_rt64) = dl_vdso_vsym (HAVE_SIGTRAMP_RT64);
#endif
#ifdef HAVE_SIGTRAMP_RT32
GLRO(dl_vdso_sigtramp_rt32) = dl_vdso_vsym (HAVE_SIGTRAMP_RT32);
#endif
#ifdef HAVE_SIGTRAMP_32
GLRO(dl_vdso_sigtramp_32) = dl_vdso_vsym (HAVE_SIGTRAMP_32);
#endif
}
#endif