elf: Fix elf_get_dynamic_info definition

Before to 490e6c62aa ('elf: Avoid nested functions in the loader
[BZ #27220]'), elf_get_dynamic_info() was defined twice on rtld.c: on
the first dynamic-link.h include and later within _dl_start().  The
former definition did not define DONT_USE_BOOTSTRAP_MAP and it is used
on setup_vdso() (since it is a global definition), while the former does
define DONT_USE_BOOTSTRAP_MAP and it is used on loader self-relocation.

With the commit change, the function is now included and defined once
instead of defined as a nested function.  So rtld.c defines without
defining RTLD_BOOTSTRAP and it brokes at least powerpc32.

This patch fixes by moving the get-dynamic-info.h include out of
dynamic-link.h, which then the caller can corirectly set the expected
semantic by defining STATIC_PIE_BOOTSTRAP, RTLD_BOOTSTRAP, and/or
RESOLVE_MAP.

It also required to enable some asserts only for the loader bootstrap
to avoid issues when called from setup_vdso().

As a side note, this is another issues with nested functions: it is
not clear from pre-processed output (-E -dD) how the function will
be build and its semantic (since nested function will be local and
extra C defines may change it).

I checked on x86_64-linux-gnu (w/o --enable-static-pie),
i686-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu-power4,
aarch64-linux-gnu, arm-linux-gnu, sparc64-linux-gnu, and
s390x-linux-gnu.

Reviewed-by: Fangrui Song <maskray@google.com>
This commit is contained in:
Adhemerval Zanella 2021-10-11 16:01:49 -03:00
parent de82cb0da4
commit 4af6982e4c
11 changed files with 27 additions and 17 deletions

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@ -16,6 +16,7 @@
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>

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@ -58,6 +58,7 @@ struct filebuf
};
#include "dynamic-link.h"
#include "get-dynamic-info.h"
#include <abi-tag.h>
#include <stackinfo.h>
#include <sysdep.h>
@ -1297,7 +1298,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
else
l->l_ld = (ElfW(Dyn) *) ((ElfW(Addr)) l->l_ld + l->l_addr);
elf_get_dynamic_info (l);
elf_get_dynamic_info (l, false);
/* Make sure we are not dlopen'ing an object that has the
DF_1_NOOPEN flag set, or a PIE object. */

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@ -28,6 +28,7 @@
#define STATIC_PIE_BOOTSTRAP
#define RESOLVE_MAP(map, scope, sym, version, flags) map
#include "dynamic-link.h"
#include "get-dynamic-info.h"
/* Relocate static executable with PIE. */
@ -51,7 +52,7 @@ _dl_relocate_static_pie (void)
break;
}
elf_get_dynamic_info (main_map);
elf_get_dynamic_info (main_map, false);
# ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
ELF_MACHINE_BEFORE_RTLD_RELOC (main_map, main_map->l_info);

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@ -19,6 +19,7 @@
#define IN_DL_RUNTIME 1 /* This can be tested in dl-machine.h. */
#include <alloca.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>

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@ -93,7 +93,6 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
#include <dl-machine.h>
#include "get-dynamic-info.h"
#ifdef RESOLVE_MAP

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@ -25,7 +25,7 @@
#include <libc-diag.h>
static inline void __attribute__ ((unused, always_inline))
elf_get_dynamic_info (struct link_map *l)
elf_get_dynamic_info (struct link_map *l, bool check)
{
#if __ELF_NATIVE_CLASS == 32
typedef Elf32_Word d_tag_utype;
@ -112,16 +112,19 @@ elf_get_dynamic_info (struct link_map *l)
assert (info[DT_RELENT]->d_un.d_val == sizeof (ElfW(Rel)));
#endif
#ifdef RTLD_BOOTSTRAP
/* Only the bind now flags are allowed. */
assert (info[VERSYMIDX (DT_FLAGS_1)] == NULL
|| (info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val & ~DF_1_NOW) == 0);
/* Flags must not be set for ld.so. */
assert (info[DT_FLAGS] == NULL
|| (info[DT_FLAGS]->d_un.d_val & ~DF_BIND_NOW) == 0);
#endif
#if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP
assert (info[DT_RUNPATH] == NULL);
assert (info[DT_RPATH] == NULL);
if (check)
{
/* Only the bind now flags are allowed. */
assert (info[VERSYMIDX (DT_FLAGS_1)] == NULL
|| (info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val & ~DF_1_NOW) == 0);
/* Flags must not be set for ld.so. */
assert (info[DT_FLAGS] == NULL
|| (info[DT_FLAGS]->d_un.d_val & ~DF_BIND_NOW) == 0);
# ifdef STATIC_PIE_BOOTSTRAP
assert (info[DT_RUNPATH] == NULL);
assert (info[DT_RPATH] == NULL);
# endif
}
#else
if (info[DT_FLAGS] != NULL)
{

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@ -513,6 +513,7 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
is trivial: always the map of ld.so itself. */
#define RTLD_BOOTSTRAP
#define RESOLVE_MAP(map, scope, sym, version, flags) map
#include "get-dynamic-info.h"
#include "dynamic-link.h"
static ElfW(Addr) __attribute_used__
@ -547,7 +548,7 @@ _dl_start (void *arg)
/* Read our own dynamic section and fill in the info array. */
bootstrap_map.l_ld = (void *) bootstrap_map.l_addr + elf_machine_dynamic ();
elf_get_dynamic_info (&bootstrap_map);
elf_get_dynamic_info (&bootstrap_map, true);
#if NO_TLS_OFFSET != 0
bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
@ -1615,7 +1616,7 @@ dl_main (const ElfW(Phdr) *phdr,
if (! rtld_is_main)
{
/* Extract the contents of the dynamic section for easy access. */
elf_get_dynamic_info (main_map);
elf_get_dynamic_info (main_map, false);
/* If the main map is libc.so, update the base namespace to
refer to this map. If libc.so is loaded later, this happens

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@ -64,7 +64,7 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
l->l_map_end += l->l_addr;
l->l_text_end += l->l_addr;
l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
elf_get_dynamic_info (l);
elf_get_dynamic_info (l, false);
_dl_setup_hash (l);
l->l_relocated = 1;

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@ -21,6 +21,7 @@
#define ELF_MACHINE_NAME "ARM"
#include <assert.h>
#include <sys/param.h>
#include <tls.h>
#include <dl-tlsdesc.h>

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@ -21,6 +21,7 @@
#define ELF_MACHINE_NAME "i386"
#include <assert.h>
#include <sys/param.h>
#include <sysdep.h>
#include <tls.h>

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@ -21,6 +21,7 @@
#define ELF_MACHINE_NAME "x86_64"
#include <assert.h>
#include <sys/param.h>
#include <sysdep.h>
#include <tls.h>