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rtld: Clean up PT_NOTE and add PT_GNU_PROPERTY handling

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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>
This commit is contained in:
Szabolcs Nagy
2020-06-22 10:56:38 +01:00
parent c1e63c7214
commit c7aa8596de
5 changed files with 119 additions and 65 deletions
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14
elf/rtld.c
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@@ -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;
}