|
| 1 | +""" |
| 2 | +reposec command |
| 3 | +
|
| 4 | +Parses all packages in a given repo and creates PackageSecurity |
| 5 | +objects which check for PIE, RELRO, Stack Canary's and Fortify. |
| 6 | +
|
| 7 | +Usage: ./manage.py reposec ARCH PATH |
| 8 | + ARCH: architecture to check |
| 9 | + PATH: full path to the repository directory. |
| 10 | +
|
| 11 | +Example: |
| 12 | + ./manage.py reposec x86_64 /srv/ftp/core |
| 13 | +""" |
| 14 | + |
| 15 | +import io |
| 16 | +import os |
| 17 | +import re |
| 18 | +import sys |
| 19 | +import logging |
| 20 | + |
| 21 | +from functools import partial |
| 22 | +from glob import glob |
| 23 | +from multiprocessing import Pool, cpu_count |
| 24 | + |
| 25 | +from elftools.elf.constants import P_FLAGS |
| 26 | +from elftools.elf.dynamic import DynamicSection |
| 27 | +from elftools.elf.elffile import ELFFile |
| 28 | +from elftools.elf.sections import SymbolTableSection |
| 29 | +from libarchive import file_reader |
| 30 | + |
| 31 | +from django.core.management.base import BaseCommand, CommandError |
| 32 | +from django.db import transaction |
| 33 | + |
| 34 | +from main.models import Arch, Package, PackageSecurity, Repo |
| 35 | + |
| 36 | + |
| 37 | +PKG_EXT = '.tar.xz' |
| 38 | +STACK_CHK = set(["__stack_chk_fail", "__stack_smash_handler"]) |
| 39 | + |
| 40 | + |
| 41 | +logging.basicConfig( |
| 42 | + level=logging.WARNING, |
| 43 | + format='%(asctime)s -> %(levelname)s: %(message)s', |
| 44 | + datefmt='%Y-%m-%d %H:%M:%S', |
| 45 | + stream=sys.stderr) |
| 46 | +TRACE = 5 |
| 47 | +logging.addLevelName(TRACE, 'TRACE') |
| 48 | +logger = logging.getLogger() |
| 49 | + |
| 50 | +class Command(BaseCommand): |
| 51 | + help = "" |
| 52 | + missing_args_message = 'missing arch and file.' |
| 53 | + |
| 54 | + def add_arguments(self, parser): |
| 55 | + parser.add_argument('args', nargs='*', help='<arch> <filename>') |
| 56 | + parser.add_argument('--processes', |
| 57 | + action='store_true', |
| 58 | + dest='processes', |
| 59 | + default=cpu_count(), |
| 60 | + help=f'number of parallel processes (default: {cpu_count()})') |
| 61 | + |
| 62 | + |
| 63 | + def handle(self, arch=None, directory=None, processes=cpu_count(), **options): |
| 64 | + if not arch: |
| 65 | + raise CommandError('Architecture is required.') |
| 66 | + if not directory: |
| 67 | + raise CommandError('Repo location is required.') |
| 68 | + directory = os.path.normpath(directory) |
| 69 | + if not os.path.exists(directory): |
| 70 | + raise CommandError('Specified repository location does not exists.') |
| 71 | + |
| 72 | + v = int(options.get('verbosity', 0)) |
| 73 | + if v == 0: |
| 74 | + logger.level = logging.ERROR |
| 75 | + elif v == 1: |
| 76 | + logger.level = logging.INFO |
| 77 | + elif v >= 2: |
| 78 | + logger.level = logging.DEBUG |
| 79 | + |
| 80 | + return read_repo(arch, directory, processes, options) |
| 81 | + |
| 82 | + |
| 83 | +def read_file(arch, repo, filename): |
| 84 | + pkgsec = None |
| 85 | + basename = os.path.basename(filename) |
| 86 | + pkgname = basename.rsplit('-', 3)[0] |
| 87 | + |
| 88 | + with file_reader(filename) as pkg: |
| 89 | + for entry in pkg: |
| 90 | + if not entry.isfile: |
| 91 | + continue |
| 92 | + |
| 93 | + # Retrieve pkgname |
| 94 | + if entry.name == '.PKGINFO': |
| 95 | + continue |
| 96 | + |
| 97 | + if not entry.name.startswith('usr/bin/'): |
| 98 | + continue |
| 99 | + |
| 100 | + fp = io.BytesIO(b''.join(entry.get_blocks())) |
| 101 | + elf = Elf(fp) |
| 102 | + |
| 103 | + if not elf.is_elf(): |
| 104 | + continue |
| 105 | + |
| 106 | + pkg = Package.objects.get(pkgname=pkgname, arch=arch, repo=repo) |
| 107 | + pkgsec = PackageSecurity(pkg=pkg, pie=elf.pie, relro=elf.relro, canary=elf.canary) |
| 108 | + |
| 109 | + return pkgsec |
| 110 | + |
| 111 | + |
| 112 | + |
| 113 | +def read_repo(arch, source_dir, processes, options): |
| 114 | + tasks = [] |
| 115 | + |
| 116 | + directory = os.path.join(source_dir, 'os', arch) |
| 117 | + for filename in glob(os.path.join(directory, f'*{PKG_EXT}')): |
| 118 | + tasks.append((filename)) |
| 119 | + |
| 120 | + arch = Arch.objects.get(name=arch) |
| 121 | + |
| 122 | + reponame = os.path.basename(source_dir).title() |
| 123 | + repo = Repo.objects.get(name=reponame) |
| 124 | + |
| 125 | + |
| 126 | + with Pool(processes=processes) as pool: |
| 127 | + results = pool.map(partial(read_file, arch, repo), tasks) |
| 128 | + |
| 129 | + results = [r for r in results if r and (not r.pie or not r.relro or not r.canary)] |
| 130 | + |
| 131 | + with transaction.atomic(): |
| 132 | + PackageSecurity.objects.all().delete() |
| 133 | + PackageSecurity.objects.bulk_create(results) |
| 134 | + |
| 135 | + |
| 136 | +class Elf: |
| 137 | + def __init__(self, fileobj): |
| 138 | + self.fileobj = fileobj |
| 139 | + self._elffile = None |
| 140 | + |
| 141 | + @property |
| 142 | + def elffile(self): |
| 143 | + if not self._elffile: |
| 144 | + self._elffile = ELFFile(self.fileobj) |
| 145 | + return self._elffile |
| 146 | + |
| 147 | + def _file_has_magic(self, fileobj, magic_bytes): |
| 148 | + length = len(magic_bytes) |
| 149 | + magic = fileobj.read(length) |
| 150 | + fileobj.seek(0) |
| 151 | + return magic == magic_bytes |
| 152 | + |
| 153 | + def is_elf(self): |
| 154 | + "Take file object, peek at the magic bytes to check if ELF file." |
| 155 | + return self._file_has_magic(self.fileobj, b"\x7fELF") |
| 156 | + |
| 157 | + def dynamic_tags(self, key): |
| 158 | + for section in self.elffile.iter_sections(): |
| 159 | + if not isinstance(section, DynamicSection): |
| 160 | + continue |
| 161 | + for tag in section.iter_tags(): |
| 162 | + if tag.entry.d_tag == key: |
| 163 | + return tag |
| 164 | + return None |
| 165 | + |
| 166 | + def rpath(self, key="DT_RPATH", verbose=False): |
| 167 | + tag = self.dynamic_tags(key) |
| 168 | + if tag and verbose: |
| 169 | + return tag.rpath |
| 170 | + if tag: |
| 171 | + return 'RPATH' |
| 172 | + return '' |
| 173 | + |
| 174 | + def runpath(self, key="DT_RUNPATH", verbose=False): |
| 175 | + tag = self.dynamic_tags(key) |
| 176 | + if tag and verbose: |
| 177 | + return tag.runpath |
| 178 | + if tag: |
| 179 | + return 'RUNPATH' |
| 180 | + |
| 181 | + return '' |
| 182 | + |
| 183 | + @property |
| 184 | + def relro(self): |
| 185 | + if self.elffile.num_segments() == 0: |
| 186 | + return "Disabled" |
| 187 | + |
| 188 | + have_relro = False |
| 189 | + for segment in self.elffile.iter_segments(): |
| 190 | + if re.search("GNU_RELRO", str(segment['p_type'])): |
| 191 | + have_relro = True |
| 192 | + break |
| 193 | + |
| 194 | + if self.dynamic_tags("DT_BIND_NOW") and have_relro: |
| 195 | + return True |
| 196 | + if have_relro: # partial |
| 197 | + return False |
| 198 | + return False |
| 199 | + |
| 200 | + @property |
| 201 | + def pie(self): |
| 202 | + header = self.elffile.header |
| 203 | + if self.dynamic_tags("EXEC"): |
| 204 | + return "Disabled" |
| 205 | + if "ET_DYN" in header['e_type']: |
| 206 | + if self.dynamic_tags("DT_DEBUG"): |
| 207 | + return True |
| 208 | + return True # DSO is PIE |
| 209 | + return False |
| 210 | + |
| 211 | + @property |
| 212 | + def canary(self): |
| 213 | + for section in self.elffile.iter_sections(): |
| 214 | + if not isinstance(section, SymbolTableSection): |
| 215 | + continue |
| 216 | + if section['sh_entsize'] == 0: |
| 217 | + continue |
| 218 | + for _, symbol in enumerate(section.iter_symbols()): |
| 219 | + if symbol.name in STACK_CHK: |
| 220 | + return True |
| 221 | + return False |
| 222 | + |
| 223 | + def program_headers(self): |
| 224 | + pflags = P_FLAGS() |
| 225 | + if self.elffile.num_segments() == 0: |
| 226 | + return "" |
| 227 | + |
| 228 | + found = False |
| 229 | + for segment in self.elffile.iter_segments(): |
| 230 | + if search("GNU_STACK", str(segment['p_type'])): |
| 231 | + found = True |
| 232 | + if segment['p_flags'] & pflags.PF_X: |
| 233 | + return "Disabled" |
| 234 | + if found: |
| 235 | + return "Enabled" |
| 236 | + return "Disabled" |
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