elf: Remove /etc/suid-debug support

Since malloc debug support moved to a different library
(libc_malloc_debug.so), the glibc.malloc.check requires preloading the
debug library to enable it.  It means that suid-debug support has not
been working since 2.34.

To restore its support, it would require to add additional information
and parsing to where to find libc_malloc_debug.so.

It is one thing less that might change AT_SECURE binaries' behavior
due to environment configurations.

Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

2 files changed, 1 insertions, 18 deletions

diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index cae67ef..24252af 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -252,20 +252,6 @@ parse_tunables (char *tunestr, char *valstring)
     tunestr[off] = '\0';
 }
 
-/* Enable the glibc.malloc.check tunable in SETUID/SETGID programs only when
-   the system administrator has created the /etc/suid-debug file.  This is a
-   special case where we want to conditionally enable/disable a tunable even
-   for setuid binaries.  We use the special version of access() to avoid
-   setting ERRNO, which is a TLS variable since TLS has not yet been set
-   up.  */
-static __always_inline void
-maybe_enable_malloc_check (void)
-{
-  tunable_id_t id = TUNABLE_ENUM_NAME (glibc, malloc, check);
-  if (__libc_enable_secure && __access_noerrno ("/etc/suid-debug", F_OK) == 0)
-    tunable_list[id].security_level = TUNABLE_SECLEVEL_NONE;
-}
-
 /* Initialize the tunables list from the environment.  For now we only use the
    ENV_ALIAS to find values.  Later we will also use the tunable names to find
    values.  */
@@ -277,8 +263,6 @@ __tunables_init (char **envp)
   size_t len = 0;
   char **prev_envp = envp;
 
-  maybe_enable_malloc_check ();
-
   while ((envp = get_next_env (envp, &envname, &len, &envval,
 			       &prev_envp)) != NULL)
     {
diff --git a/elf/rtld.c b/elf/rtld.c
index 5107d16..51b6d9f 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2670,8 +2670,7 @@ process_envvars (struct dl_main_state *state)
 	}
       while (*nextp != '\0');
 
-      if (__access ("/etc/suid-debug", F_OK) != 0)
-	GLRO(dl_debug_mask) = 0;
+      GLRO(dl_debug_mask) = 0;
 
       if (state->mode != rtld_mode_normal)
 	_exit (5);