rtld: Clean up PT_NOTE and add PT_GNU_PROPERTY handling

Add generic code to handle PT_GNU_PROPERTY notes. Invalid
content is ignored, _dl_process_pt_gnu_property is always called
after PT_LOAD segments are mapped and it has no failure modes.
Currently only one NT_GNU_PROPERTY_TYPE_0 note is handled, which
contains target specific properties: the _dl_process_gnu_property
hook is called for each property.

The old _dl_process_pt_note and _rtld_process_pt_note differ in how
the program header is read.  The old _dl_process_pt_note is called
before PT_LOAD segments are mapped and _rtld_process_pt_note is called
after PT_LOAD segments are mapped. The old _rtld_process_pt_note is
removed and _dl_process_pt_note is always called after PT_LOAD
segments are mapped and now it has no failure modes.

The program headers are scanned backwards so that PT_NOTE can be
skipped if PT_GNU_PROPERTY exists.

Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/elf/rtld.c b/elf/rtld.c
index 882b070cc0..f4c2602d65 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1507,11 +1507,17 @@ of this helper program; chances are you did not intend to run this program.\n\
 	main_map->l_relro_addr = ph->p_vaddr;
 	main_map->l_relro_size = ph->p_memsz;
 	break;
-
+      }
+  /* Process program headers again, but scan them backwards so
+     that PT_NOTE can be skipped if PT_GNU_PROPERTY exits.  */
+  for (ph = &phdr[phnum]; ph != phdr; --ph)
+    switch (ph[-1].p_type)
+      {
       case PT_NOTE:
-	if (_rtld_process_pt_note (main_map, ph))
-	  _dl_error_printf ("\
-ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
+	_dl_process_pt_note (main_map, &ph[-1]);
+	break;
+      case PT_GNU_PROPERTY:
+	_dl_process_pt_gnu_property (main_map, &ph[-1]);
 	break;
       }