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>

elf/dl-conflict.c

@@ -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>

elf/dl-load.c

@@ -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.  */

elf/dl-reloc-static-pie.c

@@ -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);

elf/dl-runtime.c

@@ -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>

elf/dynamic-link.h

@@ -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
 

elf/get-dynamic-info.h

@@ -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)
     {

elf/rtld.c

@@ -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

elf/setup-vdso.h

@@ -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;
 

sysdeps/arm/dl-machine.h

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

sysdeps/i386/dl-machine.h

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

sysdeps/x86_64/dl-machine.h

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