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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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32
sysdeps/unix/sysv/linux/dl-vdso.h
View File

@ -22,11 +22,6 @@
#include <ldsodefs.h>
#include <dl-hash.h>
/* Functions for resolving symbols in the VDSO link map. */
extern void *_dl_vdso_vsym (const char *name,
const struct r_found_version *version)
attribute_hidden;
/* If the architecture support vDSO it should define which is the expected
kernel version and hash value through both VDSO_NAME and VDSO_HASH
(usually defined at architecture sysdep.h). */
@ -38,19 +33,26 @@ extern void *_dl_vdso_vsym (const char *name,
# define VDSO_HASH 0
#endif
/* Functions for resolving symbols in the VDSO link map. */
static inline void *
get_vdso_symbol (const char *symbol)
dl_vdso_vsym (const char *name)
{
struct r_found_version rfv = { VDSO_NAME, VDSO_HASH, 1, NULL };
return _dl_vdso_vsym (symbol, &rfv);
}
struct link_map *map = GLRO (dl_sysinfo_map);
if (map == NULL)
return NULL;
static inline void *
get_vdso_mangle_symbol (const char *symbol)
{
void *vdsop = get_vdso_symbol (symbol);
PTR_MANGLE (vdsop);
return vdsop;
/* Use a WEAK REF so we don't error out if the symbol is not found. */
ElfW (Sym) wsym = { 0 };
wsym.st_info = (unsigned char) ELFW (ST_INFO (STB_WEAK, STT_NOTYPE));
struct r_found_version rfv = { VDSO_NAME, VDSO_HASH, 1, NULL };
/* Search the scope of the vdso map. */
const ElfW (Sym) *ref = &wsym;
lookup_t result = GLRO (dl_lookup_symbol_x) (name, map, &ref,
map->l_local_scope,
&rfv, 0, 0, NULL);
return ref != NULL ? DL_SYMBOL_ADDRESS (result, ref) : NULL;
}
#endif /* dl-vdso.h */