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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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30
sysdeps/unix/sysv/linux/libc-vdso.h
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@ -19,37 +19,9 @@
#ifndef _LIBC_VDSO_H
#define _LIBC_VDSO_H
#define VDSO_SYMBOL(__name) __vdso_##__name
/* Adjust the return IFUNC value from a vDSO symbol accordingly required
by the ELFv1 ABI. It is used by the architecture to create an ODP
entry since the kernel vDSO does not provide it. */
#ifndef VDSO_IFUNC_RET
# define VDSO_IFUNC_RET(__value) (__value)
#endif
#define VDSO_IFUNC_RET(__value) (__value)
#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
extern int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *)
attribute_hidden;
#endif
#ifdef HAVE_CLOCK_GETTIME64_VSYSCALL
extern int (*VDSO_SYMBOL(clock_gettime64)) (clockid_t, struct __timespec64 *)
attribute_hidden;
#endif
#ifdef HAVE_CLOCK_GETRES_VSYSCALL
extern int (*VDSO_SYMBOL(clock_getres)) (clockid_t, struct timespec *)
attribute_hidden;
#endif
#ifdef HAVE_GETTIMEOFDAY_VSYSCALL
extern int (*VDSO_SYMBOL (gettimeofday)) (struct timeval *, void *)
attribute_hidden;
#endif
#ifdef HAVE_GETCPU_VSYSCALL
extern long int (*VDSO_SYMBOL(getcpu)) (unsigned *, unsigned *, void *)
attribute_hidden;
#endif
#ifdef HAVE_TIME_VSYSCALL
extern time_t (*VDSO_SYMBOL(time)) (time_t *) attribute_hidden;
#endif
#endif /* _LIBC_VDSO_H */