mdw@git.distorted.org.uk Git - tripe/blob - keys/tripe-keys.in

   1 #! @PYTHON@
   2 ### -*-python-*-
   3 ###
   4 ### Key management and distribution
   5 ###
   6 ### (c) 2006 Straylight/Edgeware
   7 ###
   8
   9 ###----- Licensing notice ---------------------------------------------------
  10 ###
  11 ### This file is part of Trivial IP Encryption (TrIPE).
  12 ###
  13 ### TrIPE is free software; you can redistribute it and/or modify
  14 ### it under the terms of the GNU General Public License as published by
  15 ### the Free Software Foundation; either version 2 of the License, or
  16 ### (at your option) any later version.
  17 ###
  18 ### TrIPE is distributed in the hope that it will be useful,
  19 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ### GNU General Public License for more details.
  22 ###
  23 ### You should have received a copy of the GNU General Public License
  24 ### along with TrIPE; if not, write to the Free Software Foundation,
  25 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  26
  27 ###--------------------------------------------------------------------------
  28 ### External dependencies.
  29
  30 import catacomb as C
  31 import os as OS
  32 import sys as SYS
  33 import re as RX
  34 import getopt as O
  35 import shutil as SH
  36 import time as T
  37 import filecmp as FC
  38 from cStringIO import StringIO
  39 from errno import *
  40 from stat import *
  41
  42 ###--------------------------------------------------------------------------
  43 ### Useful regular expressions
  44
  45 ## Match a comment or blank line.
  46 rx_comment = RX.compile(r'^\s*(#|$)')
  47
  48 ## Match a KEY = VALUE assignment.
  49 rx_keyval = RX.compile(r'^\s*([-\w]+)(?:\s+(?!=)|\s*=\s*)(|\S|\S.*\S)\s*$')
  50
  51 ## Match a ${KEY} substitution.
  52 rx_dollarsubst = RX.compile(r'\$\{([-\w]+)\}')
  53
  54 ## Match a @TAG@ substitution.
  55 rx_atsubst = RX.compile(r'@([-\w]+)@')
  56
  57 ## Match a single non-alphanumeric character.
  58 rx_nonalpha = RX.compile(r'\W')
  59
  60 ## Match the literal string "<SEQ>".
  61 rx_seq = RX.compile(r'\<SEQ\>')
  62
  63 ## Match a shell metacharacter.
  64 rx_shmeta = RX.compile('[\\s`!"#$&*()\\[\\];\'|<>?\\\\]')
  65
  66 ## Match a character which needs escaping in a shell double-quoted string.
  67 rx_shquote = RX.compile(r'["`$\\]')
  68
  69 ###--------------------------------------------------------------------------
  70 ### Utility functions.
  71
  72 ## Exceptions.
  73 class SubprocessError (Exception): pass
  74 class VerifyError (Exception): pass
  75
  76 ## Program name and identification.
  77 quis = OS.path.basename(SYS.argv[0])
  78 PACKAGE = "@PACKAGE@"
  79 VERSION = "@VERSION@"
  80
  81 def moan(msg):
  82   """Report MSG to standard error."""
  83   SYS.stderr.write('%s: %s\n' % (quis, msg))
  84
  85 def die(msg, rc = 1):
  86   """Report MSG to standard error, and exit with code RC."""
  87   moan(msg)
  88   SYS.exit(rc)
  89
  90 def subst(s, rx, map):
  91   """
  92   Substitute values into a string.
  93
  94   Repeatedly match RX (a compiled regular expression) against the string S.
  95   For each match, extract group 1, and use it as a key to index the MAP;
  96   replace the match by the result.  Finally, return the fully-substituted
  97   string.
  98   """
  99   out = StringIO()
 100   i = 0
 101   for m in rx.finditer(s):
 102     out.write(s[i:m.start()] + map[m.group(1)])
 103     i = m.end()
 104   out.write(s[i:])
 105   return out.getvalue()
 106
 107 def shell_quotify(arg):
 108   """
 109   Quotify ARG to keep the shell happy.
 110
 111   This isn't actually used for invoking commands, just for presentation
 112   purposes; but correctness is still nice.
 113   """
 114   if not rx_shmeta.search(arg):
 115     return arg
 116   elif arg.find("'") == -1:
 117     return "'%s'" % arg
 118   else:
 119     return '"%s"' % rx_shquote.sub(lambda m: '\\' + m.group(0), arg)
 120
 121 def rmtree(path):
 122   """Delete the directory tree given by PATH."""
 123   try:
 124     st = OS.lstat(path)
 125   except OSError, err:
 126     if err.errno == ENOENT:
 127       return
 128     raise
 129   if not S_ISDIR(st.st_mode):
 130     OS.unlink(path)
 131   else:
 132     cwd = OS.getcwd()
 133     try:
 134       OS.chdir(path)
 135       for i in OS.listdir('.'):
 136         rmtree(i)
 137     finally:
 138       OS.chdir(cwd)
 139     OS.rmdir(path)
 140
 141 def zap(file):
 142   """Delete the named FILE if it exists; otherwise do nothing."""
 143   try:
 144     OS.unlink(file)
 145   except OSError, err:
 146     if err.errno == ENOENT: return
 147     raise
 148
 149 def run(args):
 150   """
 151   Run a subprocess whose arguments are given by the string ARGS.
 152
 153   The ARGS are split at word boundaries, and then subjected to configuration
 154   variable substitution (see conf_subst).  Individual argument elements
 155   beginning with `!' are split again into multiple arguments at word
 156   boundaries.
 157   """
 158   args = map(conf_subst, args.split())
 159   nargs = []
 160   for a in args:
 161     if len(a) > 0 and a[0] != '!':
 162       nargs += [a]
 163     else:
 164       nargs += a[1:].split()
 165   args = nargs
 166   print '+ %s' % ' '.join([shell_quotify(arg) for arg in args])
 167   SYS.stdout.flush()
 168   rc = OS.spawnvp(OS.P_WAIT, args[0], args)
 169   if rc != 0:
 170     raise SubprocessError, rc
 171
 172 def hexhyphens(bytes):
 173   """
 174   Convert a byte string BYTES into hex, with hyphens at each 4-byte boundary.
 175   """
 176   out = StringIO()
 177   for i in xrange(0, len(bytes)):
 178     if i > 0 and i % 4 == 0: out.write('-')
 179     out.write('%02x' % ord(bytes[i]))
 180   return out.getvalue()
 181
 182 def fingerprint(kf, ktag):
 183   """
 184   Compute the fingerprint of a key, using the user's selected hash.
 185
 186   KF is the name of a keyfile; KTAG is the tag of the key.
 187   """
 188   h = C.gchashes[conf['fingerprint-hash']]()
 189   k = C.KeyFile(kf)[ktag].fingerprint(h, '-secret')
 190   return h.done()
 191
 192 ###--------------------------------------------------------------------------
 193 ### The configuration file.
 194
 195 ## Exceptions.
 196 class ConfigFileError (Exception): pass
 197
 198 ## The configuration dictionary.
 199 conf = {}
 200
 201 def conf_subst(s):
 202   """
 203   Apply configuration substitutions to S.
 204
 205   That is, for each ${KEY} in S, replace it with the current value of the
 206   configuration variable KEY.
 207   """
 208   return subst(s, rx_dollarsubst, conf)
 209
 210 def conf_read(f):
 211   """
 212   Read the file F and insert assignments into the configuration dictionary.
 213   """
 214   lno = 0
 215   for line in file(f):
 216     lno += 1
 217     if rx_comment.match(line): continue
 218     if line[-1] == '\n': line = line[:-1]
 219     match = rx_keyval.match(line)
 220     if not match:
 221       raise ConfigFileError, "%s:%d: bad line `%s'" % (f, lno, line)
 222     k, v = match.groups()
 223     conf[k] = conf_subst(v)
 224
 225 def conf_defaults():
 226   """
 227   Apply defaults to the configuration dictionary.
 228
 229   Fill in all the interesting configuration variables based on the existing
 230   contents, as described in the manual.
 231   """
 232   for k, v in [('repos-base', 'tripe-keys.tar.gz'),
 233                ('sig-base', 'tripe-keys.sig-<SEQ>'),
 234                ('repos-url', '${base-url}${repos-base}'),
 235                ('sig-url', '${base-url}${sig-base}'),
 236                ('sig-file', '${base-dir}${sig-base}'),
 237                ('repos-file', '${base-dir}${repos-base}'),
 238                ('conf-file', '${base-dir}tripe-keys.conf'),
 239                ('upload-hook', ': run upload hook'),
 240                ('kx', 'dh'),
 241                ('kx-param', lambda: {'dh': '-LS -b3072 -B256',
 242                                      'ec': '-Cnist-p256'}[conf['kx']]),
 243                ('kx-expire', 'now + 1 year'),
 244                ('kx-warn-days', '28'),
 245                ('cipher', 'rijndael-cbc'),
 246                ('hash', 'sha256'),
 247                ('master-keygen-flags', '-l'),
 248                ('mgf', '${hash}-mgf'),
 249                ('mac', lambda: '%s-hmac/%d' %
 250                          (conf['hash'],
 251                           C.gchashes[conf['hash']].hashsz * 4)),
 252                ('sig', lambda: {'dh': 'dsa', 'ec': 'ecdsa'}[conf['kx']]),
 253                ('sig-fresh', 'always'),
 254                ('sig-genalg', lambda: {'kcdsa': 'dh',
 255                                        'dsa': 'dsa',
 256                                        'rsapkcs1': 'rsa',
 257                                        'rsapss': 'rsa',
 258                                        'ecdsa': 'ec',
 259                                        'eckcdsa': 'ec'}[conf['sig']]),
 260                ('sig-param', lambda: {'dh': '-LS -b3072 -B256',
 261                                       'dsa': '-b3072 -B256',
 262                                       'ec': '-Cnist-p256',
 263                                       'rsa': '-b3072'}[conf['sig-genalg']]),
 264                ('sig-hash', '${hash}'),
 265                ('sig-expire', 'forever'),
 266                ('fingerprint-hash', '${hash}')]:
 267     try:
 268       if k in conf: continue
 269       if type(v) == str:
 270         conf[k] = conf_subst(v)
 271       else:
 272         conf[k] = v()
 273     except KeyError, exc:
 274       if len(exc.args) == 0: raise
 275       conf[k] = '<missing-var %s>' % exc.args[0]
 276
 277 ###--------------------------------------------------------------------------
 278 ### Key-management utilities.
 279
 280 def master_keys():
 281   """
 282   Iterate over the master keys.
 283   """
 284   if not OS.path.exists('master'):
 285     return
 286   for k in C.KeyFile('master').itervalues():
 287     if (k.type != 'tripe-keys-master' or
 288         k.expiredp or
 289         not k.tag.startswith('master-')):
 290       continue #??
 291     yield k
 292
 293 def master_sequence(k):
 294   """
 295   Return the sequence number of the given master key as an integer.
 296
 297   No checking is done that K is really a master key.
 298   """
 299   return int(k.tag[7:])
 300
 301 def max_master_sequence():
 302   """
 303   Find the master key with the highest sequence number and return this
 304   sequence number.
 305   """
 306   seq = -1
 307   for k in master_keys():
 308     q = master_sequence(k)
 309     if q > seq: seq = q
 310   return seq
 311
 312 def seqsubst(x, q):
 313   """
 314   Return the value of the configuration variable X, with <SEQ> replaced by
 315   the value Q.
 316   """
 317   return rx_seq.sub(str(q), conf[x])
 318
 319 ###--------------------------------------------------------------------------
 320 ### Commands: help [COMMAND...]
 321
 322 def version(fp = SYS.stdout):
 323   fp.write('%s, %s version %s\n' % (quis, PACKAGE, VERSION))
 324
 325 def usage(fp):
 326   fp.write('Usage: %s SUBCOMMAND [ARGS...]\n' % quis)
 327
 328 def cmd_help(args):
 329   if len(args) == 0:
 330     version(SYS.stdout)
 331     print
 332     usage(SYS.stdout)
 333     print """
 334 Key management utility for TrIPE.
 335
 336 Options supported:
 337
 338 -h, --help              Show this help message.
 339 -v, --version           Show the version number.
 340 -u, --usage             Show pointlessly short usage string.
 341
 342 Subcommands available:
 343 """
 344     args = commands.keys()
 345     args.sort()
 346   for c in args:
 347     try: func, min, max, help = commands[c]
 348     except KeyError: die("unknown command `%s'" % c)
 349     print '%s%s%s' % (c, help and ' ', help)
 350
 351 ###--------------------------------------------------------------------------
 352 ### Commands: newmaster
 353
 354 def cmd_newmaster(args):
 355   seq = max_master_sequence() + 1
 356   run('''key -kmaster add
 357     -a${sig-genalg} !${sig-param}
 358     -e${sig-expire} !${master-keygen-flags} -tmaster-%d tripe-keys-master
 359     sig=${sig} hash=${sig-hash}''' % seq)
 360   run('key -kmaster extract -f-secret repos/master.pub')
 361
 362 ###--------------------------------------------------------------------------
 363 ### Commands: setup
 364
 365 def cmd_setup(args):
 366   OS.mkdir('repos')
 367   run('''key -krepos/param add
 368     -a${kx}-param !${kx-param}
 369     -eforever -tparam tripe-param
 370     kx-group=${kx} cipher=${cipher} hash=${hash} mac=${mac} mgf=${mgf}''')
 371   cmd_newmaster(args)
 372
 373 ###--------------------------------------------------------------------------
 374 ### Commands: upload
 375
 376 def cmd_upload(args):
 377
 378   ## Sanitize the repository directory
 379   umask = OS.umask(0); OS.umask(umask)
 380   mode = 0666 & ~umask
 381   for f in OS.listdir('repos'):
 382     ff = OS.path.join('repos', f)
 383     if (f.startswith('master') or f.startswith('peer-')) \
 384            and f.endswith('.old'):
 385       OS.unlink(ff)
 386       continue
 387     OS.chmod(ff, mode)
 388
 389   rmtree('tmp')
 390   OS.mkdir('tmp')
 391   OS.symlink('../repos', 'tmp/repos')
 392   cwd = OS.getcwd()
 393   try:
 394
 395     ## Build the configuration file
 396     seq = max_master_sequence()
 397     v = {'MASTER-SEQUENCE': str(seq),
 398          'HK-MASTER': hexhyphens(fingerprint('repos/master.pub',
 399                                              'master-%d' % seq))}
 400     fin = file('tripe-keys.master')
 401     fout = file('tmp/tripe-keys.conf', 'w')
 402     for line in fin:
 403       fout.write(subst(line, rx_atsubst, v))
 404     fin.close(); fout.close()
 405     SH.copyfile('tmp/tripe-keys.conf', conf_subst('${conf-file}.new'))
 406     commit = [conf['repos-file'], conf['conf-file']]
 407
 408     ## Make and sign the repository archive
 409     OS.chdir('tmp')
 410     run('tar chozf ${repos-file}.new .')
 411     OS.chdir(cwd)
 412     for k in master_keys():
 413       seq = master_sequence(k)
 414       sigfile = seqsubst('sig-file', seq)
 415       run('''catsign -kmaster sign -abdC -kmaster-%d
 416         -o%s.new ${repos-file}.new''' % (seq, sigfile))
 417       commit.append(sigfile)
 418
 419     ## Commit the changes
 420     for base in commit:
 421       new = '%s.new' % base
 422       OS.rename(new, base)
 423
 424     ## Remove files in the base-dir which don't correspond to ones we just
 425     ## committed
 426     allow = {}
 427     basedir = conf['base-dir']
 428     bdl = len(basedir)
 429     for base in commit:
 430       if base.startswith(basedir): allow[base[bdl:]] = 1
 431     for found in OS.listdir(basedir):
 432       if found not in allow: OS.remove(OS.path.join(basedir, found))
 433   finally:
 434     OS.chdir(cwd)
 435     rmtree('tmp')
 436   run('sh -c ${upload-hook}')
 437
 438 ###--------------------------------------------------------------------------
 439 ### Commands: rebuild
 440
 441 def cmd_rebuild(args):
 442   zap('keyring.pub')
 443   for i in OS.listdir('repos'):
 444     if i.startswith('peer-') and i.endswith('.pub'):
 445       run('key -kkeyring.pub merge %s' % OS.path.join('repos', i))
 446
 447 ###--------------------------------------------------------------------------
 448 ### Commands: update
 449
 450 def cmd_update(args):
 451   cwd = OS.getcwd()
 452   rmtree('tmp')
 453   try:
 454
 455     ## Fetch a new distribution
 456     OS.mkdir('tmp')
 457     OS.chdir('tmp')
 458     seq = int(conf['master-sequence'])
 459     run('curl -s -o tripe-keys.tar.gz ${repos-url}')
 460     run('curl -s -o tripe-keys.sig %s' % seqsubst('sig-url', seq))
 461     run('tar xfz tripe-keys.tar.gz')
 462
 463     ## Verify the signature
 464     want = C.bytes(rx_nonalpha.sub('', conf['hk-master']))
 465     got = fingerprint('repos/master.pub', 'master-%d' % seq)
 466     if want != got: raise VerifyError
 467     run('''catsign -krepos/master.pub verify -avC -kmaster-%d
 468       -t${sig-fresh} tripe-keys.sig tripe-keys.tar.gz''' % seq)
 469
 470     ## OK: update our copy
 471     OS.chdir(cwd)
 472     if OS.path.exists('repos'): OS.rename('repos', 'repos.old')
 473     OS.rename('tmp/repos', 'repos')
 474     if not FC.cmp('tmp/tripe-keys.conf', 'tripe-keys.conf', False):
 475       moan('configuration file changed: recommend running another update')
 476       OS.rename('tmp/tripe-keys.conf', 'tripe-keys.conf')
 477     rmtree('repos.old')
 478
 479   finally:
 480     OS.chdir(cwd)
 481     rmtree('tmp')
 482   cmd_rebuild(args)
 483
 484 ###--------------------------------------------------------------------------
 485 ### Commands: generate TAG
 486
 487 def cmd_generate(args):
 488   tag, = args
 489   keyring_pub = 'peer-%s.pub' % tag
 490   zap('keyring'); zap(keyring_pub)
 491   run('key -kkeyring merge repos/param')
 492   run('key -kkeyring add -a${kx} -pparam -e${kx-expire} -t%s tripe' %
 493       tag)
 494   run('key -kkeyring extract -f-secret %s %s' % (keyring_pub, tag))
 495
 496 ###--------------------------------------------------------------------------
 497 ### Commands: clean
 498
 499 def cmd_clean(args):
 500   rmtree('repos')
 501   rmtree('tmp')
 502   for i in OS.listdir('.'):
 503     r = i
 504     if r.endswith('.old'): r = r[:-4]
 505     if (r == 'master' or r == 'param' or
 506         r == 'keyring' or r == 'keyring.pub' or r.startswith('peer-')):
 507       zap(i)
 508
 509 ###--------------------------------------------------------------------------
 510 ### Commands: check
 511
 512 def check_key(k):
 513   now = T.time()
 514   thresh = int(conf['kx-warn-days']) * 86400
 515   if k.exptime == C.KEXP_FOREVER: return None
 516   elif k.exptime == C.KEXP_EXPIRE: left = -1
 517   else: left = k.exptime - now
 518   if left < 0:
 519     return "key `%s' HAS EXPIRED" % k.tag
 520   elif left < thresh:
 521     if left >= 86400: n, u, uu = left // 86400, 'day', 'days'
 522     else: n, u, uu = left // 3600, 'hour', 'hours'
 523     return "key `%s' EXPIRES in %d %s" % (k.tag, n, n == 1 and u or uu)
 524   else:
 525     return None
 526
 527 def cmd_check(args):
 528   if OS.path.exists('keyring.pub'):
 529     for k in C.KeyFile('keyring.pub').itervalues():
 530       whinge = check_key(k)
 531       if whinge is not None: print whinge
 532   if OS.path.exists('master'):
 533     whinges = []
 534     for k in C.KeyFile('master').itervalues():
 535       whinge = check_key(k)
 536       if whinge is None: break
 537       whinges.append(whinge)
 538     else:
 539       for whinge in whinges: print whinge
 540
 541 ###--------------------------------------------------------------------------
 542 ### Commands: mtu
 543
 544 def cmd_mtu(args):
 545   mtu, = (lambda mtu = '1500': (mtu,))(*args)
 546   mtu = int(mtu)
 547
 548   blksz = C.gcciphers[conf['cipher']].blksz
 549
 550   index = conf['mac'].find('/')
 551   if index == -1:
 552     tagsz = C.gcmacs[conf['mac']].tagsz
 553   else:
 554     tagsz = int(conf['mac'][index + 1:])/8
 555
 556   mtu -= 20                             # Minimum IP header
 557   mtu -= 8                              # UDP header
 558   mtu -= 1                              # TrIPE packet type octet
 559   mtu -= tagsz                          # MAC tag
 560   mtu -= 4                              # Sequence number
 561   mtu -= blksz                          # Initialization vector
 562
 563   print mtu
 564
 565 ###--------------------------------------------------------------------------
 566 ### Main driver.
 567
 568 commands = {'help': (cmd_help, 0, 1, ''),
 569             'newmaster': (cmd_newmaster, 0, 0, ''),
 570             'setup': (cmd_setup, 0, 0, ''),
 571             'upload': (cmd_upload, 0, 0, ''),
 572             'update': (cmd_update, 0, 0, ''),
 573             'clean': (cmd_clean, 0, 0, ''),
 574             'mtu': (cmd_mtu, 0, 1, '[PATH-MTU]'),
 575             'check': (cmd_check, 0, 0, ''),
 576             'generate': (cmd_generate, 1, 1, 'TAG'),
 577             'rebuild': (cmd_rebuild, 0, 0, '')}
 578
 579 def init():
 580   """
 581   Load the appropriate configuration file and set up the configuration
 582   dictionary.
 583   """
 584   for f in ['tripe-keys.master', 'tripe-keys.conf']:
 585     if OS.path.exists(f):
 586       conf_read(f)
 587       break
 588   conf_defaults()
 589
 590 def main(argv):
 591   """
 592   Main program: parse options and dispatch to appropriate command handler.
 593   """
 594   try:
 595     opts, args = O.getopt(argv[1:], 'hvu',
 596                           ['help', 'version', 'usage'])
 597   except O.GetoptError, exc:
 598     moan(exc)
 599     usage(SYS.stderr)
 600     SYS.exit(1)
 601   for o, v in opts:
 602     if o in ('-h', '--help'):
 603       cmd_help([])
 604       SYS.exit(0)
 605     elif o in ('-v', '--version'):
 606       version(SYS.stdout)
 607       SYS.exit(0)
 608     elif o in ('-u', '--usage'):
 609       usage(SYS.stdout)
 610       SYS.exit(0)
 611   if len(argv) < 2:
 612     cmd_help([])
 613   else:
 614     c = argv[1]
 615     try: func, min, max, help = commands[c]
 616     except KeyError: die("unknown command `%s'" % c)
 617     args = argv[2:]
 618     if len(args) < min or (max is not None and len(args) > max):
 619       SYS.stderr.write('Usage: %s %s%s%s\n' % (quis, c, help and ' ', help))
 620       SYS.exit(1)
 621     func(args)
 622
 623 ###----- That's all, folks --------------------------------------------------
 624
 625 if __name__ == '__main__':
 626   init()
 627   main(SYS.argv)