elf: Implement DT_AUDIT, DT_DEPAUDIT support [BZ #24943]

binutils ld has supported --audit, --depaudit for a long time,
only support in glibc has been missing.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/elf/rtld.c b/elf/rtld.c
index 2634e9e..b2ea21c 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -153,9 +153,17 @@ static void audit_list_init (struct audit_list *);
    not be called after audit_list_next.  */
 static void audit_list_add_string (struct audit_list *, const char *);
 
+/* Add the audit strings from the link map, found in the dynamic
+   segment at TG (either DT_AUDIT and DT_DEPAUDIT).  Must be called
+   before audit_list_next.  */
+static void audit_list_add_dynamic_tag (struct audit_list *,
+					struct link_map *,
+					unsigned int tag);
+
 /* Extract the next audit module from the audit list.  Only modules
    for which dso_name_valid_for_suid is true are returned.  Must be
-   called after all the audit_list_add_string calls.  */
+   called after all the audit_list_add_string,
+   audit_list_add_dynamic_tags calls.  */
 static const char *audit_list_next (struct audit_list *);
 
 /* This is a list of all the modes the dynamic loader can be in.  */
@@ -235,6 +243,16 @@ audit_list_add_string (struct audit_list *list, const char *string)
     list->current_tail = string;
 }
 
+static void
+audit_list_add_dynamic_tag (struct audit_list *list, struct link_map *main_map,
+			    unsigned int tag)
+{
+  ElfW(Dyn) *info = main_map->l_info[ADDRIDX (tag)];
+  const char *strtab = (const char *) D_PTR (main_map, l_info[DT_STRTAB]);
+  if (info != NULL)
+    audit_list_add_string (list, strtab + info->d_un.d_val);
+}
+
 static const char *
 audit_list_next (struct audit_list *list)
 {
@@ -1637,6 +1655,9 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
     /* Assign a module ID.  Do this before loading any audit modules.  */
     GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
 
+  audit_list_add_dynamic_tag (&audit_list, main_map, DT_AUDIT);
+  audit_list_add_dynamic_tag (&audit_list, main_map, DT_DEPAUDIT);
+
   /* If we have auditing DSOs to load, do it now.  */
   bool need_security_init = true;
   if (audit_list.length > 0)