137 lines
4.5 KiB
Python
Executable File
137 lines
4.5 KiB
Python
Executable File
#!/usr/bin/python3
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"""
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Check debug symbols are present in shared object and can identify
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code.
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It starts scanning from a directory and recursively scans all ELF
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files found in it for various symbols to ensure all debuginfo is
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present and nothing has been stripped.
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Usage:
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./check-debug-symbols /path/of/dir/to/scan/
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Example:
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./check-debug-symbols /usr/lib64
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"""
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# This technique was explained to me by Mark Wielaard (mjw).
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import collections
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import os
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import re
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import subprocess
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import sys
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ScanResult = collections.namedtuple('ScanResult',
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'file_name debug_info debug_abbrev file_symbols gnu_debuglink')
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def scan_file(file):
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"Scan the provided file and return a ScanResult containing results of the scan."
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# Test for .debug_* sections in the shared object. This is the main test.
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# Stripped objects will not contain these.
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readelf_S_result = subprocess.run(['eu-readelf', '-S', file],
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stdout=subprocess.PIPE, encoding='utf-8', check=True)
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has_debug_info = any(line for line in readelf_S_result.stdout.split('\n') if '] .debug_info' in line)
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has_debug_abbrev = any(line for line in readelf_S_result.stdout.split('\n') if '] .debug_abbrev' in line)
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# Test FILE symbols. These will most likely be removed by anyting that
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# manipulates symbol tables because it's generally useless. So a nice test
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# that nothing has messed with symbols.
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def contains_file_symbols(line):
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parts = line.split()
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if len(parts) < 8:
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return False
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return \
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parts[2] == '0' and parts[3] == 'FILE' and parts[4] == 'LOCAL' and parts[5] == 'DEFAULT' and \
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parts[6] == 'ABS' and re.match(r'((.*/)?[-_a-zA-Z0-9]+\.(c|cc|cpp|cxx))?', parts[7])
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readelf_s_result = subprocess.run(["eu-readelf", '-s', file],
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stdout=subprocess.PIPE, encoding='utf-8', check=True)
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has_file_symbols = any(line for line in readelf_s_result.stdout.split('\n') if contains_file_symbols(line))
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# Test that there are no .gnu_debuglink sections pointing to another
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# debuginfo file. There shouldn't be any debuginfo files, so the link makes
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# no sense either.
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has_gnu_debuglink = any(line for line in readelf_s_result.stdout.split('\n') if '] .gnu_debuglink' in line)
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return ScanResult(file, has_debug_info, has_debug_abbrev, has_file_symbols, has_gnu_debuglink)
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def is_elf(file):
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result = subprocess.run(['file', file], stdout=subprocess.PIPE, encoding='utf-8', check=True)
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return re.search(r'ELF 64-bit [LM]SB (?:pie )?(?:executable|shared object)', result.stdout)
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def scan_file_if_sensible(file):
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if is_elf(file):
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# print(file)
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return scan_file(file)
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return None
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def scan_dir(dir):
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results = []
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for root, _, files in os.walk(dir):
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for name in files:
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result = scan_file_if_sensible(os.path.join(root, name))
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if result:
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results.append(result)
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return results
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def scan(file):
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file = os.path.abspath(file)
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if os.path.isdir(file):
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return scan_dir(file)
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elif os.path.isfile(file):
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return [scan_file_if_sensible(file)]
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def is_bad_result(result):
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return not result.debug_info or not result.debug_abbrev or not result.file_symbols or result.gnu_debuglink
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def print_scan_results(results, verbose):
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# print(results)
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for result in results:
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file_name = result.file_name
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found_issue = False
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if not result.debug_info:
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found_issue = True
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print('error: missing .debug_info section in', file_name)
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if not result.debug_abbrev:
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found_issue = True
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print('error: missing .debug_abbrev section in', file_name)
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if not result.file_symbols:
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found_issue = True
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print('error: missing FILE symbols in', file_name)
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if result.gnu_debuglink:
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found_issue = True
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print('error: unexpected .gnu_debuglink section in', file_name)
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if verbose and not found_issue:
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print('OK: ', file_name)
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def main(args):
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verbose = False
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files = []
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for arg in args:
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if arg == '--verbose' or arg == '-v':
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verbose = True
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else:
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files.append(arg)
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results = []
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for file in files:
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results.extend(scan(file))
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print_scan_results(results, verbose)
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if any(is_bad_result(result) for result in results):
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return 1
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return 0
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if __name__ == '__main__':
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sys.exit(main(sys.argv[1:]))
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