elf: Issue la_symbind for bind-now (BZ #23734)

The audit symbind callback is not called for binaries built with
-Wl,-z,now or when LD_BIND_NOW=1 is used, nor the PLT tracking callbacks
(plt_enter and plt_exit) since this would change the expected
program semantics (where no PLT is expected) and would have performance
implications (such as for BZ#15533).

LAV_CURRENT is also bumped to indicate the audit ABI change (where
la_symbind flags are set by the loader to indicate no possible PLT
trace).

To handle powerpc64 ELFv1 function descriptor, _dl_audit_symbind
requires to know whether bind-now is used so the symbol value is
updated to function text segment instead of the OPD (for lazy binding
this is done by PPC64_LOAD_FUNCPTR on _dl_runtime_resolve).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc64-linux-gnu.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 61acf41..34151fb 100644
--- a/NEWS
+++ b/NEWS
@@ -168,6 +168,10 @@ Deprecated and removed features, and other changes affecting compatibility:
   removal of the LD_TRACE_PRELINKING, and LD_USE_LOAD_BIAS, environment
   variables and their functionality in the dynamic loader.
 
+* The audit module interface version LAV_CURRENT is increased to enable
+  proper bind-now support.  The loader now advertises via the la_symbind
+  flags that PLT trace is not possible.
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]