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1"""Fixed Linux editor protocol. Invoked in memory; never installed on the server.

3All path walks use directory descriptors and O_NOFOLLOW. The working copy is

4retained even after replacement: only a subsequent confirmed cleanup removes it.

5"""

6import base64

7import errno

8import fcntl

9import hashlib

10import json

11import os

12import pwd

13import re

14import secrets

15import stat

16import sys

18LIMIT = 25 * 1024 * 1024

19REPLACED = False

22def fail(code):

23 raise ValueError(code)

26def directory(path, privileged=False):

27 if not path.startswith('/') or '\x00' in path or any(p in ('.', '..') for p in path.split('/')):

28 fail('FILE_UNSAFE_PATH')

29 fd = os.open('/', os.O_RDONLY | os.O_DIRECTORY)

30 try:

31 def trusted(value):

32 s = os.fstat(value)

33 if privileged and (s.st_uid != 0 or s.st_mode & 0o022 or 'system.posix_acl_access' in os.listxattr(value)):

34 fail('FILE_UNSAFE_PRIVILEGED_DIRECTORY')

35 trusted(fd)

36 for part in filter(None, path.split('/')):

37 nxt = os.open(part, os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW, dir_fd=fd)

38 os.close(fd)

39 fd = nxt

40 trusted(fd)

41 return fd

42 except BaseException:

43 os.close(fd)

44 raise

47def regular(parent, name, owner=None, private=False):

48 fd = os.open(name, os.O_RDONLY | os.O_NOFOLLOW | os.O_NONBLOCK, dir_fd=parent)

49 s = os.fstat(fd)

    if not stat.S_ISREG(s.st_mode) or s.st_nlink != 1 or (owner is not None and s.st_uid != owner) or (private and stat.S_IMODE(s.st_mode) != 0o600):

51 os.close(fd)

52 fail('FILE_UNSAFE_TYPE_OR_LINK')

53 return fd

56def attributes(fd):

57 # Linux ACLs, capabilities and SELinux labels are extended attributes too.

58 # Fail closed if any attribute cannot be read or reproduced.

59 return {k: base64.b64encode(os.getxattr(fd, k)).decode('ascii') for k in sorted(os.listxattr(fd))}

62def snapshot(fd):

63 before = os.fstat(fd)

64 if before.st_size > LIMIT:

65 fail('FILE_TOO_LARGE')

66 os.lseek(fd, 0, os.SEEK_SET)

67 pieces = []

68 length = 0

69 while True:

70 piece = os.read(fd, min(65536, LIMIT + 1 - length))

71 if not piece:

72 break

73 pieces.append(piece)

74 length += len(piece)

75 if length > LIMIT:

76 fail('FILE_TOO_LARGE')

77 data = b''.join(pieces)

78 xattrs = attributes(fd)

79 after = os.fstat(fd)

    if (before.st_ino, before.st_size, before.st_mtime_ns, before.st_ctime_ns) != (after.st_ino, after.st_size, after.st_mtime_ns, after.st_ctime_ns):

81 fail('FILE_CONFLICT')

82 meta = dict(dev=after.st_dev, ino=after.st_ino, uid=after.st_uid, gid=after.st_gid,

83 mode=stat.S_IMODE(after.st_mode), size=after.st_size,

84 mtimeNs=str(after.st_mtime_ns), ctimeNs=str(after.st_ctime_ns), xattrs=xattrs,

85 hash=hashlib.sha256(data).hexdigest())

86 return data, meta

89def target(path, privileged=False):

90 parent, name = os.path.split(path)

91 if not name or name in ('.', '..'):

92 fail('FILE_UNSAFE_PATH')

93 d = directory(parent, privileged)

94 try:

95 return d, name, regular(d, name)

96 except BaseException:

97 os.close(d)

98 raise

100

101def workspace(uid=None):

102 uid = os.getuid() if uid is None else uid

103 home = pwd.getpwuid(uid).pw_dir

104 h = directory(home)

105 try:

106 hs = os.fstat(h)

107 if hs.st_uid != uid or hs.st_mode & 0o022 or 'system.posix_acl_access' in os.listxattr(h):

108 fail('FILE_UNSAFE_WORKSPACE')

109 try:

110 os.mkdir('ch-j-sm', 0o700, dir_fd=h)

111 except FileExistsError:

112 pass

113 d = os.open('ch-j-sm', os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW, dir_fd=h)

114 s = os.fstat(d)

115 if s.st_uid != uid:

116 os.close(d)

117 fail('FILE_UNSAFE_WORKSPACE')

118 os.fchmod(d, 0o700)

119 return d, os.path.join(home, 'ch-j-sm'), uid

120 finally:

121 os.close(h)

122

123

124def operation_id(value):

125 if not re.fullmatch('[a-f0-9]{32}', str(value)):

126 fail('FILE_INVALID_RECOVERY_ID')

127 return value

128

129

130def names(value):

131 value = operation_id(value)

132 return '.' + value + '.tmp', '.' + value + '.json'

133

134

135def put_record(d, name, value):

136 data = json.dumps(value).encode('ascii')

137 if len(data) > 256 * 1024:

138 fail('FILE_METADATA_UNSUPPORTED')

139 fd = os.open(name, os.O_WRONLY | os.O_CREAT | os.O_EXCL | os.O_NOFOLLOW, 0o600, dir_fd=d)

140 with os.fdopen(fd, 'wb') as out:

141 os.fchmod(out.fileno(), 0o600)

142 out.write(data)

143 out.flush()

144 os.fsync(out.fileno())

145 os.fsync(d)

146

147

148def get_record(d, name, uid):

149 fd = regular(d, name, uid, True)

150 with os.fdopen(fd, 'rb') as inp:

151 raw = inp.read(256 * 1024 + 1)

152 if len(raw) > 256 * 1024:

153 fail('FILE_INVALID_RECOVERY_RECORD')

154 record = json.loads(raw)

155 if not re.fullmatch('[a-f0-9]{64}', record['hash']):

156 fail('FILE_INVALID_RECOVERY_RECORD')

157 return record

158

159

160def preserved(actual, original):

161 return all(actual[k] == original[k] for k in ('uid', 'gid', 'mode', 'xattrs'))

162

163

164def inspect_record(d, uid, value, include_text=False):

165 tmp, journal = names(value)

166 r = get_record(d, journal, uid)

167 fd = regular(d, tmp, uid, True)

168 try:

169 data, staged = snapshot(fd)

170 finally:

171 os.close(fd)

172 complete = staged['hash'] == r['hash']

173 state = 'upload-incomplete'

174 if complete:

175 state = 'recovery-available'

176 try:

177 td, name, t = target(r['path'])

178 try:

179 _, current = snapshot(t)

180 if current['hash'] == r['hash'] and preserved(current, r['baseline']):

181 state = 'confirmed'

182 elif current != r['baseline']:

183 state = 'conflict'

184 finally:

185 os.close(t)

186 os.close(td)

187 except OSError:

188 pass # Permission denied/disconnected from target: copy remains useful.

189 result = dict(recoveryId=value, path=r['path'], status=state, hash=staged['hash'], complete=complete)

190 if include_text:

191 if not complete:

192 fail('FILE_UPLOAD_INCOMPLETE')

193 result['data'] = base64.b64encode(data).decode('ascii')

194 return result

195

196

197def run(a):

198 global REPLACED

199 op = a['operation']

200 if op == 'read':

201 d, name, fd = target(a['path'])

202 try:

203 data, meta = snapshot(fd)

204 return dict(data=base64.b64encode(data).decode('ascii'), baseline=meta)

205 finally:

206 os.close(fd)

207 os.close(d)

208 d, home, uid = workspace(a.get('uid') if op != 'prepare' else None)

209 try:

210 if op == 'identity':

211 return dict(uid=uid)

212 if op == 'prepare':

213 tmp, journal = names(a['id'])

214 put_record(d, journal, dict(path=a['path'], baseline=a['baseline'], hash=a['hash']))

215 return dict(temporary=home + '/' + tmp, uid=uid, recoveryId=a['id'])

216 if op == 'list':

217 results = []

218 for name in sorted(os.listdir(d))[:10000]:

219 if re.fullmatch(r'\.[a-f0-9]{32}\.json', name):

220 try:

221 results.append(inspect_record(d, uid, name[1:-5]))

222 except (OSError, ValueError, KeyError):

223 results.append(dict(recoveryId=name[1:-5], status='inspection-unavailable'))

224 return dict(items=results)

225 tmp, journal = names(a['id'])

226 if op in ('inspect', 'cleanup'):

227 result = inspect_record(d, uid, a['id'], op == 'inspect')

228 if op == 'cleanup':

229 if result['status'] != 'confirmed':

230 fail('FILE_RESULT_UNCONFIRMED')

231 os.unlink(tmp, dir_fd=d)

232 os.unlink(journal, dir_fd=d)

233 os.fsync(d)

234 return result

235 if op != 'finalize':

236 fail('FILE_INVALID_OPERATION')

237 source = regular(d, tmp, uid, True)

238 try:

239 data, staged = snapshot(source)

240 if staged['hash'] != a['hash']:

241 fail('FILE_UPLOAD_INCOMPLETE')

242 os.fsync(source)

243 td, name, old = target(a['path'], os.geteuid() == 0)

244 destination = '.chj-save-' + secrets.token_hex(16) + '.tmp'

245 created = False

246 try:

247 fcntl.flock(old, fcntl.LOCK_EX | fcntl.LOCK_NB)

248 _, baseline = snapshot(old)

249 if baseline != a['baseline']:

250 fail('FILE_CONFLICT')

251 # Copying a content/inode-bound integrity signature would leave

252 # invalid security metadata. Re-signing requires a separate flow.

253 if set(baseline['xattrs']) & {'security.ima', 'security.evm'}:

254 fail('FILE_METADATA_UNSUPPORTED')

255 dest = os.open(destination, os.O_RDWR | os.O_CREAT | os.O_EXCL | os.O_NOFOLLOW, 0o600, dir_fd=td)

256 created = True

257 try:

258 # Write fully before applying security metadata (capabilities

259 # and setuid bits can be cleared by writes or chown).

260 with os.fdopen(os.dup(dest), 'wb') as out:

261 out.write(data)

262 out.flush()

263 ds = os.fstat(dest)

264 if (ds.st_uid, ds.st_gid) != (baseline['uid'], baseline['gid']):

265 os.fchown(dest, baseline['uid'], baseline['gid'])

266 os.fchmod(dest, baseline['mode'])

267 for key in os.listxattr(dest):

268 if key not in baseline['xattrs']:

269 os.removexattr(dest, key)

270 for key, value in baseline['xattrs'].items():

271 os.setxattr(dest, key, base64.b64decode(value))

272 _, ready = snapshot(dest)

273 if ready['hash'] != a['hash'] or not preserved(ready, baseline):

274 fail('FILE_METADATA_UNSUPPORTED')

275 os.fsync(dest)

276 # Detect writes, chmod/chown, link changes and path replacement

277 # while preparing. flock serializes cooperating editor saves.

278 _, current = snapshot(old)

279 linked = os.stat(name, dir_fd=td, follow_symlinks=False)

280

                    if current != baseline or linked.st_ino != baseline['ino'] or linked.st_dev != baseline['dev'] or linked.st_nlink != 1:

281 fail('FILE_CONFLICT')

282 os.replace(destination, name, src_dir_fd=td, dst_dir_fd=td)

283 REPLACED = True

284 created = False

285 os.fsync(td)

286 check_dir, check_name, verified = target(a['path'])

287 try:

288 _, final = snapshot(verified)

289 finally:

290 os.close(verified)

291 os.close(check_dir)

292 if final['ino'] != ready['ino'] or final['hash'] != a['hash'] or not preserved(final, baseline):

293 fail('FILE_RESULT_UNCONFIRMED')

294 return dict(status='saved', baseline=final, hash=final['hash'])

295 finally:

296 os.close(dest)

297 finally:

298 if created:

299 try:

300 os.unlink(destination, dir_fd=td)

301 except OSError:

302 pass

303 os.close(old)

304 os.close(td)

305 finally:

306 os.close(source)

307 finally:

308 os.close(d)

309

310

311try:

312 if sys.platform != 'linux':

313 fail('FILE_LINUX_REQUIRED')

314 print(json.dumps(dict(ok=True, value=run(json.loads(sys.argv[1])))))

315except BlockingIOError:

316 print(json.dumps(dict(ok=False, code='FILE_CONFLICT')))

317except PermissionError:

318 print(json.dumps(dict(ok=False, code='FILE_RESULT_UNKNOWN' if REPLACED else 'FILE_PERMISSION_DENIED')))

319except FileNotFoundError:

320 print(json.dumps(dict(ok=False, code='FILE_RESULT_UNKNOWN' if REPLACED else 'FILE_NOT_FOUND')))

321except OSError as e:

322 code = 'FILE_UNSAFE_PATH' if e.errno in (errno.ELOOP, errno.ENOTDIR) else 'FILE_REMOTE_IO_FAILED'

323 print(json.dumps(dict(ok=False, code='FILE_RESULT_UNKNOWN' if REPLACED else code)))

324except (ValueError, KeyError, TypeError):

325 e = sys.exc_info()[1]

326 code = str(e) if re.fullmatch('FILE_[A-Z_]+', str(e)) else 'FILE_PROTOCOL_ERROR'

327 print(json.dumps(dict(ok=False, code='FILE_RESULT_UNKNOWN' if REPLACED else code)))

328

SHA-256: 64e39a9361357921026ee1e88fec63c55d785cf112af0e560d6177bfdd09409b

SHA-256 des Archivs: 5ac91caf4fa32a6fdb114f2430deed486fbe7489d5eea343d1f034169fafb5e0