1 #!/usr/bin/env python 2 # 3 # Copyright (C) 2009 The Android Open Source Project 4 # 5 # Licensed under the Apache License, Version 2.0 (the "License"); 6 # you may not use this file except in compliance with the License. 7 # You may obtain a copy of the License at 8 # 9 # http://www.apache.org/licenses/LICENSE-2.0 10 # 11 # Unless required by applicable law or agreed to in writing, software 12 # distributed under the License is distributed on an "AS IS" BASIS, 13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 # See the License for the specific language governing permissions and 15 # limitations under the License. 16 17 """ 18 Check the signatures of all APKs in a target_files .zip file. With 19 -c, compare the signatures of each package to the ones in a separate 20 target_files (usually a previously distributed build for the same 21 device) and flag any changes. 22 23 Usage: check_target_file_signatures [flags] target_files 24 25 -c (--compare_with) <other_target_files> 26 Look for compatibility problems between the two sets of target 27 files (eg., packages whose keys have changed). 28 29 -l (--local_cert_dirs) <dir,dir,...> 30 Comma-separated list of top-level directories to scan for 31 .x509.pem files. Defaults to "vendor,build". Where cert files 32 can be found that match APK signatures, the filename will be 33 printed as the cert name, otherwise a hash of the cert plus its 34 subject string will be printed instead. 35 36 -t (--text) 37 Dump the certificate information for both packages in comparison 38 mode (this output is normally suppressed). 39 40 """ 41 42 import sys 43 44 if sys.hexversion < 0x02070000: 45 print >> sys.stderr, "Python 2.7 or newer is required." 46 sys.exit(1) 47 48 import os 49 import re 50 import shutil 51 import subprocess 52 import zipfile 53 54 import common 55 56 # Work around a bug in python's zipfile module that prevents opening 57 # of zipfiles if any entry has an extra field of between 1 and 3 bytes 58 # (which is common with zipaligned APKs). This overrides the 59 # ZipInfo._decodeExtra() method (which contains the bug) with an empty 60 # version (since we don't need to decode the extra field anyway). 61 class MyZipInfo(zipfile.ZipInfo): 62 def _decodeExtra(self): 63 pass 64 zipfile.ZipInfo = MyZipInfo 65 66 OPTIONS = common.OPTIONS 67 68 OPTIONS.text = False 69 OPTIONS.compare_with = None 70 OPTIONS.local_cert_dirs = ("vendor", "build") 71 72 PROBLEMS = [] 73 PROBLEM_PREFIX = [] 74 75 def AddProblem(msg): 76 PROBLEMS.append(" ".join(PROBLEM_PREFIX) + " " + msg) 77 def Push(msg): 78 PROBLEM_PREFIX.append(msg) 79 def Pop(): 80 PROBLEM_PREFIX.pop() 81 82 83 def Banner(msg): 84 print "-" * 70 85 print " ", msg 86 print "-" * 70 87 88 89 def GetCertSubject(cert): 90 p = common.Run(["openssl", "x509", "-inform", "DER", "-text"], 91 stdin=subprocess.PIPE, 92 stdout=subprocess.PIPE) 93 out, err = p.communicate(cert) 94 if err and not err.strip(): 95 return "(error reading cert subject)" 96 for line in out.split("\n"): 97 line = line.strip() 98 if line.startswith("Subject:"): 99 return line[8:].strip() 100 return "(unknown cert subject)" 101 102 103 class CertDB(object): 104 def __init__(self): 105 self.certs = {} 106 107 def Add(self, cert, name=None): 108 if cert in self.certs: 109 if name: 110 self.certs[cert] = self.certs[cert] + "," + name 111 else: 112 if name is None: 113 name = "unknown cert %s (%s)" % (common.sha1(cert).hexdigest()[:12], 114 GetCertSubject(cert)) 115 self.certs[cert] = name 116 117 def Get(self, cert): 118 """Return the name for a given cert.""" 119 return self.certs.get(cert, None) 120 121 def FindLocalCerts(self): 122 to_load = [] 123 for top in OPTIONS.local_cert_dirs: 124 for dirpath, _, filenames in os.walk(top): 125 certs = [os.path.join(dirpath, i) 126 for i in filenames if i.endswith(".x509.pem")] 127 if certs: 128 to_load.extend(certs) 129 130 for i in to_load: 131 f = open(i) 132 cert = common.ParseCertificate(f.read()) 133 f.close() 134 name, _ = os.path.splitext(i) 135 name, _ = os.path.splitext(name) 136 self.Add(cert, name) 137 138 ALL_CERTS = CertDB() 139 140 141 def CertFromPKCS7(data, filename): 142 """Read the cert out of a PKCS#7-format file (which is what is 143 stored in a signed .apk).""" 144 Push(filename + ":") 145 try: 146 p = common.Run(["openssl", "pkcs7", 147 "-inform", "DER", 148 "-outform", "PEM", 149 "-print_certs"], 150 stdin=subprocess.PIPE, 151 stdout=subprocess.PIPE) 152 out, err = p.communicate(data) 153 if err and not err.strip(): 154 AddProblem("error reading cert:\n" + err) 155 return None 156 157 cert = common.ParseCertificate(out) 158 if not cert: 159 AddProblem("error parsing cert output") 160 return None 161 return cert 162 finally: 163 Pop() 164 165 166 class APK(object): 167 def __init__(self, full_filename, filename): 168 self.filename = filename 169 self.certs = None 170 self.shared_uid = None 171 self.package = None 172 173 Push(filename+":") 174 try: 175 self.RecordCerts(full_filename) 176 self.ReadManifest(full_filename) 177 finally: 178 Pop() 179 180 def RecordCerts(self, full_filename): 181 out = set() 182 try: 183 f = open(full_filename) 184 apk = zipfile.ZipFile(f, "r") 185 pkcs7 = None 186 for info in apk.infolist(): 187 if info.filename.startswith("META-INF/") and \ 188 (info.filename.endswith(".DSA") or info.filename.endswith(".RSA")): 189 pkcs7 = apk.read(info.filename) 190 cert = CertFromPKCS7(pkcs7, info.filename) 191 out.add(cert) 192 ALL_CERTS.Add(cert) 193 if not pkcs7: 194 AddProblem("no signature") 195 finally: 196 f.close() 197 self.certs = frozenset(out) 198 199 def ReadManifest(self, full_filename): 200 p = common.Run(["aapt", "dump", "xmltree", full_filename, 201 "AndroidManifest.xml"], 202 stdout=subprocess.PIPE) 203 manifest, err = p.communicate() 204 if err: 205 AddProblem("failed to read manifest") 206 return 207 208 self.shared_uid = None 209 self.package = None 210 211 for line in manifest.split("\n"): 212 line = line.strip() 213 m = re.search(r'A: (\S*?)(?:\(0x[0-9a-f]+\))?="(.*?)" \(Raw', line) 214 if m: 215 name = m.group(1) 216 if name == "android:sharedUserId": 217 if self.shared_uid is not None: 218 AddProblem("multiple sharedUserId declarations") 219 self.shared_uid = m.group(2) 220 elif name == "package": 221 if self.package is not None: 222 AddProblem("multiple package declarations") 223 self.package = m.group(2) 224 225 if self.package is None: 226 AddProblem("no package declaration") 227 228 229 class TargetFiles(object): 230 def __init__(self): 231 self.max_pkg_len = 30 232 self.max_fn_len = 20 233 self.apks = None 234 self.apks_by_basename = None 235 self.certmap = None 236 237 def LoadZipFile(self, filename): 238 d, z = common.UnzipTemp(filename, ['*.apk']) 239 try: 240 self.apks = {} 241 self.apks_by_basename = {} 242 for dirpath, _, filenames in os.walk(d): 243 for fn in filenames: 244 if fn.endswith(".apk"): 245 fullname = os.path.join(dirpath, fn) 246 displayname = fullname[len(d)+1:] 247 apk = APK(fullname, displayname) 248 self.apks[apk.filename] = apk 249 self.apks_by_basename[os.path.basename(apk.filename)] = apk 250 251 self.max_pkg_len = max(self.max_pkg_len, len(apk.package)) 252 self.max_fn_len = max(self.max_fn_len, len(apk.filename)) 253 finally: 254 shutil.rmtree(d) 255 256 self.certmap = common.ReadApkCerts(z) 257 z.close() 258 259 def CheckSharedUids(self): 260 """Look for any instances where packages signed with different 261 certs request the same sharedUserId.""" 262 apks_by_uid = {} 263 for apk in self.apks.itervalues(): 264 if apk.shared_uid: 265 apks_by_uid.setdefault(apk.shared_uid, []).append(apk) 266 267 for uid in sorted(apks_by_uid.keys()): 268 apks = apks_by_uid[uid] 269 for apk in apks[1:]: 270 if apk.certs != apks[0].certs: 271 break 272 else: 273 # all packages have the same set of certs; this uid is fine. 274 continue 275 276 AddProblem("different cert sets for packages with uid %s" % (uid,)) 277 278 print "uid %s is shared by packages with different cert sets:" % (uid,) 279 for apk in apks: 280 print "%-*s [%s]" % (self.max_pkg_len, apk.package, apk.filename) 281 for cert in apk.certs: 282 print " ", ALL_CERTS.Get(cert) 283 print 284 285 def CheckExternalSignatures(self): 286 for apk_filename, certname in self.certmap.iteritems(): 287 if certname == "EXTERNAL": 288 # Apps marked EXTERNAL should be signed with the test key 289 # during development, then manually re-signed after 290 # predexopting. Consider it an error if this app is now 291 # signed with any key that is present in our tree. 292 apk = self.apks_by_basename[apk_filename] 293 name = ALL_CERTS.Get(apk.cert) 294 if not name.startswith("unknown "): 295 Push(apk.filename) 296 AddProblem("hasn't been signed with EXTERNAL cert") 297 Pop() 298 299 def PrintCerts(self): 300 """Display a table of packages grouped by cert.""" 301 by_cert = {} 302 for apk in self.apks.itervalues(): 303 for cert in apk.certs: 304 by_cert.setdefault(cert, []).append((apk.package, apk)) 305 306 order = [(-len(v), k) for (k, v) in by_cert.iteritems()] 307 order.sort() 308 309 for _, cert in order: 310 print "%s:" % (ALL_CERTS.Get(cert),) 311 apks = by_cert[cert] 312 apks.sort() 313 for _, apk in apks: 314 if apk.shared_uid: 315 print " %-*s %-*s [%s]" % (self.max_fn_len, apk.filename, 316 self.max_pkg_len, apk.package, 317 apk.shared_uid) 318 else: 319 print " %-*s %s" % (self.max_fn_len, apk.filename, apk.package) 320 print 321 322 def CompareWith(self, other): 323 """Look for instances where a given package that exists in both 324 self and other have different certs.""" 325 326 all_apks = set(self.apks.keys()) 327 all_apks.update(other.apks.keys()) 328 329 max_pkg_len = max(self.max_pkg_len, other.max_pkg_len) 330 331 by_certpair = {} 332 333 for i in all_apks: 334 if i in self.apks: 335 if i in other.apks: 336 # in both; should have same set of certs 337 if self.apks[i].certs != other.apks[i].certs: 338 by_certpair.setdefault((other.apks[i].certs, 339 self.apks[i].certs), []).append(i) 340 else: 341 print "%s [%s]: new APK (not in comparison target_files)" % ( 342 i, self.apks[i].filename) 343 else: 344 if i in other.apks: 345 print "%s [%s]: removed APK (only in comparison target_files)" % ( 346 i, other.apks[i].filename) 347 348 if by_certpair: 349 AddProblem("some APKs changed certs") 350 Banner("APK signing differences") 351 for (old, new), packages in sorted(by_certpair.items()): 352 for i, o in enumerate(old): 353 if i == 0: 354 print "was", ALL_CERTS.Get(o) 355 else: 356 print " ", ALL_CERTS.Get(o) 357 for i, n in enumerate(new): 358 if i == 0: 359 print "now", ALL_CERTS.Get(n) 360 else: 361 print " ", ALL_CERTS.Get(n) 362 for i in sorted(packages): 363 old_fn = other.apks[i].filename 364 new_fn = self.apks[i].filename 365 if old_fn == new_fn: 366 print " %-*s [%s]" % (max_pkg_len, i, old_fn) 367 else: 368 print " %-*s [was: %s; now: %s]" % (max_pkg_len, i, 369 old_fn, new_fn) 370 print 371 372 373 def main(argv): 374 def option_handler(o, a): 375 if o in ("-c", "--compare_with"): 376 OPTIONS.compare_with = a 377 elif o in ("-l", "--local_cert_dirs"): 378 OPTIONS.local_cert_dirs = [i.strip() for i in a.split(",")] 379 elif o in ("-t", "--text"): 380 OPTIONS.text = True 381 else: 382 return False 383 return True 384 385 args = common.ParseOptions(argv, __doc__, 386 extra_opts="c:l:t", 387 extra_long_opts=["compare_with=", 388 "local_cert_dirs="], 389 extra_option_handler=option_handler) 390 391 if len(args) != 1: 392 common.Usage(__doc__) 393 sys.exit(1) 394 395 ALL_CERTS.FindLocalCerts() 396 397 Push("input target_files:") 398 try: 399 target_files = TargetFiles() 400 target_files.LoadZipFile(args[0]) 401 finally: 402 Pop() 403 404 compare_files = None 405 if OPTIONS.compare_with: 406 Push("comparison target_files:") 407 try: 408 compare_files = TargetFiles() 409 compare_files.LoadZipFile(OPTIONS.compare_with) 410 finally: 411 Pop() 412 413 if OPTIONS.text or not compare_files: 414 Banner("target files") 415 target_files.PrintCerts() 416 target_files.CheckSharedUids() 417 target_files.CheckExternalSignatures() 418 if compare_files: 419 if OPTIONS.text: 420 Banner("comparison files") 421 compare_files.PrintCerts() 422 target_files.CompareWith(compare_files) 423 424 if PROBLEMS: 425 print "%d problem(s) found:\n" % (len(PROBLEMS),) 426 for p in PROBLEMS: 427 print p 428 return 1 429 430 return 0 431 432 433 if __name__ == '__main__': 434 try: 435 r = main(sys.argv[1:]) 436 sys.exit(r) 437 except common.ExternalError as e: 438 print 439 print " ERROR: %s" % (e,) 440 print 441 sys.exit(1) 442
