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-genalg', lambda: {'dh': 'dh',
 242                                       'ec': 'ec'}[conf['kx']]),
 243                ('kx-param-genalg', lambda: {'dh': 'dh-param',
 244                                             'ec': 'ec-param'}[conf['kx']]),
 245                ('kx-param', lambda: {'dh': '-LS -b3072 -B256',
 246                                      'ec': '-Cnist-p256'}[conf['kx']]),
 247                ('kx-expire', 'now + 1 year'),
 248                ('kx-warn-days', '28'),
 249                ('cipher', 'rijndael-cbc'),
 250                ('hash', 'sha256'),
 251                ('master-keygen-flags', '-l'),
 252                ('mgf', '${hash}-mgf'),
 253                ('mac', lambda: '%s-hmac/%d' %
 254                          (conf['hash'],
 255                           C.gchashes[conf['hash']].hashsz * 4)),
 256                ('sig', lambda: {'dh': 'dsa', 'ec': 'ecdsa'}[conf['kx']]),
 257                ('sig-fresh', 'always'),
 258                ('sig-genalg', lambda: {'kcdsa': 'dh',
 259                                        'dsa': 'dsa',
 260                                        'rsapkcs1': 'rsa',
 261                                        'rsapss': 'rsa',
 262                                        'ecdsa': 'ec',
 263                                        'eckcdsa': 'ec'}[conf['sig']]),
 264                ('sig-param', lambda: {'dh': '-LS -b3072 -B256',
 265                                       'dsa': '-b3072 -B256',
 266                                       'ec': '-Cnist-p256',
 267                                       'rsa': '-b3072'}[conf['sig-genalg']]),
 268                ('sig-hash', '${hash}'),
 269                ('sig-expire', 'forever'),
 270                ('fingerprint-hash', '${hash}')]:
 271     try:
 272       if k in conf: continue
 273       if type(v) == str:
 274         conf[k] = conf_subst(v)
 275       else:
 276         conf[k] = v()
 277     except KeyError, exc:
 278       if len(exc.args) == 0: raise
 279       conf[k] = '<missing-var %s>' % exc.args[0]
 280
 281 ###--------------------------------------------------------------------------
 282 ### Key-management utilities.
 283
 284 def master_keys():
 285   """
 286   Iterate over the master keys.
 287   """
 288   if not OS.path.exists('master'):
 289     return
 290   for k in C.KeyFile('master').itervalues():
 291     if (k.type != 'tripe-keys-master' or
 292         k.expiredp or
 293         not k.tag.startswith('master-')):
 294       continue #??
 295     yield k
 296
 297 def master_sequence(k):
 298   """
 299   Return the sequence number of the given master key as an integer.
 300
 301   No checking is done that K is really a master key.
 302   """
 303   return int(k.tag[7:])
 304
 305 def max_master_sequence():
 306   """
 307   Find the master key with the highest sequence number and return this
 308   sequence number.
 309   """
 310   seq = -1
 311   for k in master_keys():
 312     q = master_sequence(k)
 313     if q > seq: seq = q
 314   return seq
 315
 316 def seqsubst(x, q):
 317   """
 318   Return the value of the configuration variable X, with <SEQ> replaced by
 319   the value Q.
 320   """
 321   return rx_seq.sub(str(q), conf[x])
 322
 323 ###--------------------------------------------------------------------------
 324 ### Commands: help [COMMAND...]
 325
 326 def version(fp = SYS.stdout):
 327   fp.write('%s, %s version %s\n' % (quis, PACKAGE, VERSION))
 328
 329 def usage(fp):
 330   fp.write('Usage: %s SUBCOMMAND [ARGS...]\n' % quis)
 331
 332 def cmd_help(args):
 333   if len(args) == 0:
 334     version(SYS.stdout)
 335     print
 336     usage(SYS.stdout)
 337     print """
 338 Key management utility for TrIPE.
 339
 340 Options supported:
 341
 342 -h, --help              Show this help message.
 343 -v, --version           Show the version number.
 344 -u, --usage             Show pointlessly short usage string.
 345
 346 Subcommands available:
 347 """
 348     args = commands.keys()
 349     args.sort()
 350   for c in args:
 351     try: func, min, max, help = commands[c]
 352     except KeyError: die("unknown command `%s'" % c)
 353     print '%s%s%s' % (c, help and ' ', help)
 354
 355 ###--------------------------------------------------------------------------
 356 ### Commands: newmaster
 357
 358 def cmd_newmaster(args):
 359   seq = max_master_sequence() + 1
 360   run('''key -kmaster add
 361     -a${sig-genalg} !${sig-param}
 362     -e${sig-expire} !${master-keygen-flags} -tmaster-%d tripe-keys-master
 363     sig=${sig} hash=${sig-hash}''' % seq)
 364   run('key -kmaster extract -f-secret repos/master.pub')
 365
 366 ###--------------------------------------------------------------------------
 367 ### Commands: setup
 368
 369 def cmd_setup(args):
 370   OS.mkdir('repos')
 371   run('''key -krepos/param add
 372     -a${kx-param-genalg} !${kx-param}
 373     -eforever -tparam tripe-param
 374     kx-group=${kx} cipher=${cipher} hash=${hash} mac=${mac} mgf=${mgf}''')
 375   cmd_newmaster(args)
 376
 377 ###--------------------------------------------------------------------------
 378 ### Commands: upload
 379
 380 def cmd_upload(args):
 381
 382   ## Sanitize the repository directory
 383   umask = OS.umask(0); OS.umask(umask)
 384   mode = 0666 & ~umask
 385   for f in OS.listdir('repos'):
 386     ff = OS.path.join('repos', f)
 387     if (f.startswith('master') or f.startswith('peer-')) \
 388            and f.endswith('.old'):
 389       OS.unlink(ff)
 390       continue
 391     OS.chmod(ff, mode)
 392
 393   rmtree('tmp')
 394   OS.mkdir('tmp')
 395   OS.symlink('../repos', 'tmp/repos')
 396   cwd = OS.getcwd()
 397   try:
 398
 399     ## Build the configuration file
 400     seq = max_master_sequence()
 401     v = {'MASTER-SEQUENCE': str(seq),
 402          'HK-MASTER': hexhyphens(fingerprint('repos/master.pub',
 403                                              'master-%d' % seq))}
 404     fin = file('tripe-keys.master')
 405     fout = file('tmp/tripe-keys.conf', 'w')
 406     for line in fin:
 407       fout.write(subst(line, rx_atsubst, v))
 408     fin.close(); fout.close()
 409     SH.copyfile('tmp/tripe-keys.conf', conf_subst('${conf-file}.new'))
 410     commit = [conf['repos-file'], conf['conf-file']]
 411
 412     ## Make and sign the repository archive
 413     OS.chdir('tmp')
 414     run('tar chozf ${repos-file}.new .')
 415     OS.chdir(cwd)
 416     for k in master_keys():
 417       seq = master_sequence(k)
 418       sigfile = seqsubst('sig-file', seq)
 419       run('''catsign -kmaster sign -abdC -kmaster-%d
 420         -o%s.new ${repos-file}.new''' % (seq, sigfile))
 421       commit.append(sigfile)
 422
 423     ## Commit the changes
 424     for base in commit:
 425       new = '%s.new' % base
 426       OS.rename(new, base)
 427
 428     ## Remove files in the base-dir which don't correspond to ones we just
 429     ## committed
 430     allow = {}
 431     basedir = conf['base-dir']
 432     bdl = len(basedir)
 433     for base in commit:
 434       if base.startswith(basedir): allow[base[bdl:]] = 1
 435     for found in OS.listdir(basedir):
 436       if found not in allow: OS.remove(OS.path.join(basedir, found))
 437   finally:
 438     OS.chdir(cwd)
 439     rmtree('tmp')
 440   run('sh -c ${upload-hook}')
 441
 442 ###--------------------------------------------------------------------------
 443 ### Commands: rebuild
 444
 445 def cmd_rebuild(args):
 446   zap('keyring.pub')
 447   for i in OS.listdir('repos'):
 448     if i.startswith('peer-') and i.endswith('.pub'):
 449       run('key -kkeyring.pub merge %s' % OS.path.join('repos', i))
 450
 451 ###--------------------------------------------------------------------------
 452 ### Commands: update
 453
 454 def cmd_update(args):
 455   cwd = OS.getcwd()
 456   rmtree('tmp')
 457   try:
 458
 459     ## Fetch a new distribution
 460     OS.mkdir('tmp')
 461     OS.chdir('tmp')
 462     seq = int(conf['master-sequence'])
 463     run('curl -s -o tripe-keys.tar.gz ${repos-url}')
 464     run('curl -s -o tripe-keys.sig %s' % seqsubst('sig-url', seq))
 465     run('tar xfz tripe-keys.tar.gz')
 466
 467     ## Verify the signature
 468     want = C.bytes(rx_nonalpha.sub('', conf['hk-master']))
 469     got = fingerprint('repos/master.pub', 'master-%d' % seq)
 470     if want != got: raise VerifyError
 471     run('''catsign -krepos/master.pub verify -avC -kmaster-%d
 472       -t${sig-fresh} tripe-keys.sig tripe-keys.tar.gz''' % seq)
 473
 474     ## OK: update our copy
 475     OS.chdir(cwd)
 476     if OS.path.exists('repos'): OS.rename('repos', 'repos.old')
 477     OS.rename('tmp/repos', 'repos')
 478     if not FC.cmp('tmp/tripe-keys.conf', 'tripe-keys.conf', False):
 479       moan('configuration file changed: recommend running another update')
 480       OS.rename('tmp/tripe-keys.conf', 'tripe-keys.conf')
 481     rmtree('repos.old')
 482
 483   finally:
 484     OS.chdir(cwd)
 485     rmtree('tmp')
 486   cmd_rebuild(args)
 487
 488 ###--------------------------------------------------------------------------
 489 ### Commands: generate TAG
 490
 491 def cmd_generate(args):
 492   tag, = args
 493   keyring_pub = 'peer-%s.pub' % tag
 494   zap('keyring'); zap(keyring_pub)
 495   run('key -kkeyring merge repos/param')
 496   run('key -kkeyring add -a${kx-genalg} -pparam -e${kx-expire} -t%s tripe' %
 497       tag)
 498   run('key -kkeyring extract -f-secret %s %s' % (keyring_pub, tag))
 499
 500 ###--------------------------------------------------------------------------
 501 ### Commands: clean
 502
 503 def cmd_clean(args):
 504   rmtree('repos')
 505   rmtree('tmp')
 506   for i in OS.listdir('.'):
 507     r = i
 508     if r.endswith('.old'): r = r[:-4]
 509     if (r == 'master' or r == 'param' or
 510         r == 'keyring' or r == 'keyring.pub' or r.startswith('peer-')):
 511       zap(i)
 512
 513 ###--------------------------------------------------------------------------
 514 ### Commands: check
 515
 516 def check_key(k):
 517   now = T.time()
 518   thresh = int(conf['kx-warn-days']) * 86400
 519   if k.exptime == C.KEXP_FOREVER: return None
 520   elif k.exptime == C.KEXP_EXPIRE: left = -1
 521   else: left = k.exptime - now
 522   if left < 0:
 523     return "key `%s' HAS EXPIRED" % k.tag
 524   elif left < thresh:
 525     if left >= 86400: n, u, uu = left // 86400, 'day', 'days'
 526     else: n, u, uu = left // 3600, 'hour', 'hours'
 527     return "key `%s' EXPIRES in %d %s" % (k.tag, n, n == 1 and u or uu)
 528   else:
 529     return None
 530
 531 def cmd_check(args):
 532   if OS.path.exists('keyring.pub'):
 533     for k in C.KeyFile('keyring.pub').itervalues():
 534       whinge = check_key(k)
 535       if whinge is not None: print whinge
 536   if OS.path.exists('master'):
 537     whinges = []
 538     for k in C.KeyFile('master').itervalues():
 539       whinge = check_key(k)
 540       if whinge is None: break
 541       whinges.append(whinge)
 542     else:
 543       for whinge in whinges: print whinge
 544
 545 ###--------------------------------------------------------------------------
 546 ### Commands: mtu
 547
 548 def cmd_mtu(args):
 549   mtu, = (lambda mtu = '1500': (mtu,))(*args)
 550   mtu = int(mtu)
 551
 552   blksz = C.gcciphers[conf['cipher']].blksz
 553
 554   index = conf['mac'].find('/')
 555   if index == -1:
 556     tagsz = C.gcmacs[conf['mac']].tagsz
 557   else:
 558     tagsz = int(conf['mac'][index + 1:])/8
 559
 560   mtu -= 20                             # Minimum IP header
 561   mtu -= 8                              # UDP header
 562   mtu -= 1                              # TrIPE packet type octet
 563   mtu -= tagsz                          # MAC tag
 564   mtu -= 4                              # Sequence number
 565   mtu -= blksz                          # Initialization vector
 566
 567   print mtu
 568
 569 ###--------------------------------------------------------------------------
 570 ### Main driver.
 571
 572 commands = {'help': (cmd_help, 0, 1, ''),
 573             'newmaster': (cmd_newmaster, 0, 0, ''),
 574             'setup': (cmd_setup, 0, 0, ''),
 575             'upload': (cmd_upload, 0, 0, ''),
 576             'update': (cmd_update, 0, 0, ''),
 577             'clean': (cmd_clean, 0, 0, ''),
 578             'mtu': (cmd_mtu, 0, 1, '[PATH-MTU]'),
 579             'check': (cmd_check, 0, 0, ''),
 580             'generate': (cmd_generate, 1, 1, 'TAG'),
 581             'rebuild': (cmd_rebuild, 0, 0, '')}
 582
 583 def init():
 584   """
 585   Load the appropriate configuration file and set up the configuration
 586   dictionary.
 587   """
 588   for f in ['tripe-keys.master', 'tripe-keys.conf']:
 589     if OS.path.exists(f):
 590       conf_read(f)
 591       break
 592   conf_defaults()
 593
 594 def main(argv):
 595   """
 596   Main program: parse options and dispatch to appropriate command handler.
 597   """
 598   try:
 599     opts, args = O.getopt(argv[1:], 'hvu',
 600                           ['help', 'version', 'usage'])
 601   except O.GetoptError, exc:
 602     moan(exc)
 603     usage(SYS.stderr)
 604     SYS.exit(1)
 605   for o, v in opts:
 606     if o in ('-h', '--help'):
 607       cmd_help([])
 608       SYS.exit(0)
 609     elif o in ('-v', '--version'):
 610       version(SYS.stdout)
 611       SYS.exit(0)
 612     elif o in ('-u', '--usage'):
 613       usage(SYS.stdout)
 614       SYS.exit(0)
 615   if len(argv) < 2:
 616     cmd_help([])
 617   else:
 618     c = argv[1]
 619     try: func, min, max, help = commands[c]
 620     except KeyError: die("unknown command `%s'" % c)
 621     args = argv[2:]
 622     if len(args) < min or (max is not None and len(args) > max):
 623       SYS.stderr.write('Usage: %s %s%s%s\n' % (quis, c, help and ' ', help))
 624       SYS.exit(1)
 625     func(args)
 626
 627 ###----- That's all, folks --------------------------------------------------
 628
 629 if __name__ == '__main__':
 630   init()
 631   main(SYS.argv)