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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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3
sysdeps/unix/sysv/linux/gettimeofday.c
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@ -25,6 +25,7 @@
# ifdef SHARED
# include <dl-vdso.h>
# include <libc-vdso.h>
static int
__gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
@ -36,7 +37,7 @@ __gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
# undef INIT_ARCH
# define INIT_ARCH() \
void *vdso_gettimeofday = get_vdso_symbol (HAVE_GETTIMEOFDAY_VSYSCALL)
void *vdso_gettimeofday = dl_vdso_vsym (HAVE_GETTIMEOFDAY_VSYSCALL)
libc_ifunc (__gettimeofday,
vdso_gettimeofday ? VDSO_IFUNC_RET (vdso_gettimeofday)
: (void *) __gettimeofday_syscall)