e auth - use our memclear and fill it out with modern zeroing methods

so memset_s still doesn't get detected (add a check anyway), but there
are other alternatives, so detect and use them if found
(explicit_bzero, explicit_memset) in addition to the generally
"practically works" memset ptr method we had and.. just to be extra
safe add an asm memory barrier to this fallback. also.. mlock the
passwd memory in lokker (if it doesn't work - don't worry - there is
nothing we can do, so we did our best) to avoid this memory gettign
swapped etc.

meson.build

@@ -186,6 +186,18 @@ if cc.has_header('execinfo.h') == true
 elif cc.has_function('backtrace_symbols_fd', dependencies: 'execinfo') == false
   execinfo_dep = dependency('execinfo', required: false)
 endif
+if cc.has_function('explicit_bzero') == true
+  config_h.set('HAVE_EXPLICIT_BZERO'   , '1')
+endif
+if cc.has_function('explicit_memset') == true
+  config_h.set('HAVE_EXPLICIT_MEMSET'  , '1')
+endif
+if cc.has_function('memset_s') == true
+  config_h.set('HAVE_MEMSET_S'         , '1')
+endif
+if cc.has_function('mlock') == true
+  config_h.set('HAVE_MLOCK'            , '1')
+endif
 
 if cc.has_header('fnmatch.h') == false
   error('fnmatch.h not found')

src/bin/e_auth.c

@@ -3,7 +3,7 @@
 E_API int
 e_auth_begin(char *passwd)
 {
-   char buf[PATH_MAX], *p;
+   char buf[PATH_MAX];
    Ecore_Exe *exe = NULL;
    int ret = 0;
    size_t pwlen;
@@ -31,9 +31,7 @@ e_auth_begin(char *passwd)
 out:
    if (exe) ecore_exe_free(exe);
 
-   /* security - null out passwd string once we are done with it */
-   for (p = passwd; *p; p++) *p = 0;
-   if (passwd[rand() % pwlen]) fprintf(stderr, "ACK!\n");
+   e_util_memclear(passwd, pwlen);
    return ret;
 }
 

src/bin/e_utils.c

@@ -1458,25 +1458,29 @@ e_util_evas_objects_above_print_smart(Evas_Object *o)
      }
 }
 
-/*
- * NOTICE: This function should not be used by external modules!!!
- *
- * This function is just a hack to allow us to "securely" clear sensitive
- * info until memset_s() is readily available, or at least we move this hack
- * to Eina.
- *
- * This is going to work until link time optimizations are good enough.
- * Hopefully by then, we'll be able to properly use memset_s().
- */
-static void *(* const volatile memset_ptr)(void *, int, size_t) = memset;
+#if   defined(HAVE_MEMSET_S)
+#elif defined(HAVE_EXPLICIT_BZERO)
+#elif defined(HAVE_EXPLICIT_MEMSET)
+#else
+void *(* const volatile __memset_ptr)(void *, int, size_t) = memset;
+#endif
 
 E_API void
 e_util_memclear(void *s, size_t n)
 {
-   memset_ptr(s, 0, n);
+   if (n == 0) return;
+#if   defined(HAVE_MEMSET_S)
+   memset_s(s, n, 0, n);
+#elif defined(HAVE_EXPLICIT_BZERO)
+   explicit_bzero(s, n);
+#elif defined(HAVE_EXPLICIT_MEMSET)
+   explicit_memset(s, 0, n);
+#else
+   __memset_ptr(s, 0, n);
+   __asm__ __volatile__("": :"r"(s) : "memory");
+#endif
 }
 
-
 E_API Ecore_Exe *
 e_util_open(const char *exe, void *data)
 {

src/modules/lokker/lokker.c

@@ -1,4 +1,5 @@
 #include "e_mod_main.h"
+#include <sys/mman.h>
 
 #define PASSWD_LEN                256
 
@@ -858,6 +859,9 @@ lokker_lock(void)
      }
    edd = E_NEW(Lokker_Data, 1);
    if (!edd) return EINA_FALSE;
+#ifdef HAVE_MLOCK
+   mlock(edd, sizeof(Lokker_Data));
+#endif
 
    E_LIST_FOREACH(e_comp->zones, _lokker_popup_add);
    total_zone_num = eina_list_count(e_comp->zones);
@@ -881,5 +885,8 @@ lokker_unlock(void)
    E_FREE_LIST(edd->handlers, ecore_event_handler_del);
    if (edd->move_handler) ecore_event_handler_del(edd->move_handler);
 
+#ifdef HAVE_MLOCK
+   munlock(edd, sizeof(Lokker_Data));
+#endif
    E_FREE(edd);
 }