glibc/elf/tst-relro-symbols.py
Florian Weimer 198abcbb94 Default to --with-default-link=no (bug 25812)
This is necessary to place the libio vtables into the RELRO segment.
New tests elf/tst-relro-ldso and elf/tst-relro-libc are added to
verify that this is what actually happens.

The new tests fail on ia64 due to lack of (default) RELRO support
inbutils, so they are XFAILed there.
2022-04-22 10:59:03 +02:00

138 lines
5.4 KiB
Python

#!/usr/bin/python3
# Verify that certain symbols are covered by RELRO.
# Copyright (C) 2022 Free Software Foundation, Inc.
# This file is part of the GNU C Library.
#
# The GNU C Library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# The GNU C Library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with the GNU C Library; if not, see
# <https://www.gnu.org/licenses/>.
"""Analyze a (shared) object to verify that certain symbols are
present and covered by the PT_GNU_RELRO segment.
"""
import argparse
import os.path
import sys
# Make available glibc Python modules.
sys.path.append(os.path.join(
os.path.dirname(os.path.realpath(__file__)), os.path.pardir, 'scripts'))
import glibcelf
def find_relro(path: str, img: glibcelf.Image) -> (int, int):
"""Discover the address range of the PT_GNU_RELRO segment."""
for phdr in img.phdrs():
if phdr.p_type == glibcelf.Pt.PT_GNU_RELRO:
# The computation is not entirely accurate because
# _dl_protect_relro in elf/dl-reloc.c rounds both the
# start end and downwards using the run-time page size.
return phdr.p_vaddr, phdr.p_vaddr + phdr.p_memsz
sys.stdout.write('{}: error: no PT_GNU_RELRO segment\n'.format(path))
sys.exit(1)
def check_in_relro(kind, relro_begin, relro_end, name, start, size, error):
"""Check if a section or symbol falls within in the RELRO segment."""
end = start + size - 1
if not (relro_begin <= start < end < relro_end):
error(
'{} {!r} of size {} at 0x{:x} is not in RELRO range [0x{:x}, 0x{:x})'.format(
kind, name.decode('UTF-8'), start, size,
relro_begin, relro_end))
def get_parser():
"""Return an argument parser for this script."""
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('object', help='path to object file to check')
parser.add_argument('--required', metavar='NAME', default=(),
help='required symbol names', nargs='*')
parser.add_argument('--optional', metavar='NAME', default=(),
help='required symbol names', nargs='*')
return parser
def main(argv):
"""The main entry point."""
parser = get_parser()
opts = parser.parse_args(argv)
img = glibcelf.Image.readfile(opts.object)
required_symbols = frozenset([sym.encode('UTF-8')
for sym in opts.required])
optional_symbols = frozenset([sym.encode('UTF-8')
for sym in opts.optional])
check_symbols = required_symbols | optional_symbols
# Tracks the symbols in check_symbols that have been found.
symbols_found = set()
# Discover the extent of the RELRO segment.
relro_begin, relro_end = find_relro(opts.object, img)
symbol_table_found = False
errors = False
def error(msg: str) -> None:
"""Record an error condition and write a message to standard output."""
nonlocal errors
errors = True
sys.stdout.write('{}: error: {}\n'.format(opts.object, msg))
# Iterate over section headers to find the symbol table.
for shdr in img.shdrs():
if shdr.sh_type == glibcelf.Sht.SHT_SYMTAB:
symbol_table_found = True
for sym in img.syms(shdr):
if sym.st_name in check_symbols:
symbols_found.add(sym.st_name)
# Validate symbol type, section, and size.
if sym.st_info.type != glibcelf.Stt.STT_OBJECT:
error('symbol {!r} has wrong type {}'.format(
sym.st_name.decode('UTF-8'), sym.st_info.type))
if sym.st_shndx in glibcelf.Shn:
error('symbol {!r} has reserved section {}'.format(
sym.st_name.decode('UTF-8'), sym.st_shndx))
continue
if sym.st_size == 0:
error('symbol {!r} has size zero'.format(
sym.st_name.decode('UTF-8')))
continue
check_in_relro('symbol', relro_begin, relro_end,
sym.st_name, sym.st_value, sym.st_size,
error)
continue # SHT_SYMTAB
if shdr.sh_name == b'.data.rel.ro' \
or shdr.sh_name.startswith(b'.data.rel.ro.'):
check_in_relro('section', relro_begin, relro_end,
shdr.sh_name, shdr.sh_addr, shdr.sh_size,
error)
continue
if required_symbols - symbols_found:
for sym in sorted(required_symbols - symbols_found):
error('symbol {!r} not found'.format(sym.decode('UTF-8')))
if errors:
sys.exit(1)
if not symbol_table_found:
sys.stdout.write(
'{}: warning: no symbol table found (stripped object)\n'.format(
opts.object))
sys.exit(77)
if __name__ == '__main__':
main(sys.argv[1:])