Downstream-only patch to change rtld_active () to return true during

early audit operations.  GLRO (_dl_profile_output) is initialized much

earlier than GLRO (dl_init_all_dirs), before auditors run, so it is a

good replacement.

This is addressed downstream very differently, in this commit:

commit 8dcb6d0af07fda3607b541857e4f3970a74ed55b

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue Apr 26 14:23:02 2022 +0200

    dlfcn: Do not use rtld_active () to determine ld.so state (bug 29078)

    When audit modules are loaded, ld.so initialization is not yet

    complete, and rtld_active () returns false even though ld.so is

    mostly working.  Instead, the static dlopen hook is used, but that

    does not work at all because this is not a static dlopen situation.

    Commit 466c1ea15f461edb8e3ffaf5d86d708876343bbf ("dlfcn: Rework

    static dlopen hooks") moved the hook pointer into _rtld_global_ro,

    which means that separate protection is not needed anymore and the

    hook pointer can be checked directly.

    The guard for disabling libio vtable hardening in _IO_vtable_check

    should stay for now.

    Fixes commit 8e1472d2c1e25e6eabc2059170731365f6d5b3d1 ("ld.so:

    Examine GLRO to detect inactive loader [BZ #20204]").

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/elf/rtld.c b/elf/rtld.c

index 22cceeab40319582..b47e84ca2fb6f03c 100644

--- a/elf/rtld.c

+++ b/elf/rtld.c

@@ -2352,9 +2352,7 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);

   GLRO(dl_initial_searchlist) = *GL(dl_ns)[LM_ID_BASE]._ns_main_searchlist;

   /* Remember the last search directory added at startup, now that

-     malloc will no longer be the one from dl-minimal.c.  As a side

-     effect, this marks ld.so as initialized, so that the rtld_active

-     function returns true from now on.  */

+     malloc will no longer be the one from dl-minimal.c.  */

   GLRO(dl_init_all_dirs) = GL(dl_all_dirs);

   /* Print scope information.  */

@@ -2675,7 +2673,9 @@ process_envvars (struct dl_main_state *state)

   char *envline;

   char *debug_output = NULL;

-  /* This is the default place for profiling data file.  */

+  /* This is the default place for profiling data file.  As a side

+     effect, this marks ld.so as initialized, so that the rtld_active

+     function returns true from now on.  */

   GLRO(dl_profile_output)

     = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];

diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h

index d4f70211c34d1c59..9dec9e3d3b6d6aa2 100644

--- a/sysdeps/generic/ldsodefs.h

+++ b/sysdeps/generic/ldsodefs.h

@@ -600,18 +600,18 @@ struct rtld_global_ro

   /* Name of the shared object to be profiled (if any).  */

   EXTERN const char *_dl_profile;

-  /* Filename of the output file.  */

+  /* Filename of the output file.  This is assigned a

+     non-NULL pointer by the ld.so startup code (after initialization

+     to NULL), so this can also serve as an indicator whether a copy

+     of ld.so is initialized and active.  See the rtld_active function

+     below.  */

   EXTERN const char *_dl_profile_output;

   /* Name of the object we want to trace the prelinking.  */

   EXTERN const char *_dl_trace_prelink;

   /* Map of shared object to be prelink traced.  */

   EXTERN struct link_map *_dl_trace_prelink_map;

-  /* All search directories defined at startup.  This is assigned a

-     non-NULL pointer by the ld.so startup code (after initialization

-     to NULL), so this can also serve as an indicator whether a copy

-     of ld.so is initialized and active.  See the rtld_active function

-     below.  */

+  /* All search directories defined at startup.  */

   EXTERN struct r_search_path_elem *_dl_init_all_dirs;

 #ifdef NEED_DL_SYSINFO

@@ -1259,9 +1259,9 @@ static inline bool

 rtld_active (void)

 {

   /* The default-initialized variable does not have a non-zero

-     dl_init_all_dirs member, so this allows us to recognize an

+     dl_profile_output member, so this allows us to recognize an

      initialized and active ld.so copy.  */

-  return GLRO(dl_init_all_dirs) != NULL;

+  return GLRO(dl_profile_output) != NULL;

 }

 static inline struct auditstate *