| 1 | ### -*-python-*- |
| 2 | ### |
| 3 | ### Management of a secure password database |
| 4 | ### |
| 5 | ### (c) 2005 Straylight/Edgeware |
| 6 | ### |
| 7 | |
| 8 | ###----- Licensing notice --------------------------------------------------- |
| 9 | ### |
| 10 | ### This file is part of the Python interface to Catacomb. |
| 11 | ### |
| 12 | ### Catacomb/Python is free software; you can redistribute it and/or modify |
| 13 | ### it under the terms of the GNU General Public License as published by |
| 14 | ### the Free Software Foundation; either version 2 of the License, or |
| 15 | ### (at your option) any later version. |
| 16 | ### |
| 17 | ### Catacomb/Python is distributed in the hope that it will be useful, |
| 18 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | ### GNU General Public License for more details. |
| 21 | ### |
| 22 | ### You should have received a copy of the GNU General Public License along |
| 23 | ### with Catacomb/Python; if not, write to the Free Software Foundation, |
| 24 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 25 | |
| 26 | ###-------------------------------------------------------------------------- |
| 27 | ### Imported modules. |
| 28 | |
| 29 | from __future__ import with_statement |
| 30 | |
| 31 | import errno as _E |
| 32 | import os as _OS |
| 33 | from cStringIO import StringIO as _StringIO |
| 34 | |
| 35 | import catacomb as _C |
| 36 | |
| 37 | ###-------------------------------------------------------------------------- |
| 38 | ### Text encoding utilities. |
| 39 | |
| 40 | def _literalp(s): |
| 41 | """ |
| 42 | Answer whether S can be represented literally. |
| 43 | |
| 44 | If True, then S can be stored literally, as a metadata item name or |
| 45 | value; if False, then S requires some kind of encoding. |
| 46 | """ |
| 47 | return all(ch.isalnum() or ch in '-_:' for ch in s) |
| 48 | |
| 49 | def _enc_metaname(name): |
| 50 | """Encode NAME as a metadata item name, returning the result.""" |
| 51 | if _literalp(name): |
| 52 | return name |
| 53 | else: |
| 54 | sio = _StringIO() |
| 55 | sio.write('!') |
| 56 | for ch in name: |
| 57 | if _literalp(ch): sio.write(ch) |
| 58 | elif ch == ' ': sio.write('+') |
| 59 | else: sio.write('%%%02x' % ord(ch)) |
| 60 | return sio.getvalue() |
| 61 | |
| 62 | def _dec_metaname(name): |
| 63 | """Decode NAME as a metadata item name, returning the result.""" |
| 64 | if not name.startswith('!'): |
| 65 | return name |
| 66 | else: |
| 67 | sio = _StringIO() |
| 68 | i, n = 1, len(name) |
| 69 | while i < n: |
| 70 | ch = name[i] |
| 71 | i += 1 |
| 72 | if ch == '+': |
| 73 | sio.write(' ') |
| 74 | elif ch == '%': |
| 75 | sio.write(chr(int(name[i:i + 2], 16))) |
| 76 | i += 2 |
| 77 | else: |
| 78 | sio.write(ch) |
| 79 | return sio.getvalue() |
| 80 | |
| 81 | def _b64(s): |
| 82 | """Encode S as base64, without newlines, and trimming `=' padding.""" |
| 83 | return s.encode('base64').translate(None, '\n=') |
| 84 | def _unb64(s): |
| 85 | """Decode S as base64 with trimmed `=' padding.""" |
| 86 | return (s + '='*((4 - len(s))%4)).decode('base64') |
| 87 | |
| 88 | def _enc_metaval(val): |
| 89 | """Encode VAL as a metadata item value, returning the result.""" |
| 90 | if _literalp(val): return val |
| 91 | else: return '?' + _b64(val) |
| 92 | |
| 93 | def _dec_metaval(val): |
| 94 | """Decode VAL as a metadata item value, returning the result.""" |
| 95 | if not val.startswith('?'): return val |
| 96 | else: return _unb64(val[1:]) |
| 97 | |
| 98 | ###-------------------------------------------------------------------------- |
| 99 | ### Underlying cryptography. |
| 100 | |
| 101 | class DecryptError (Exception): |
| 102 | """ |
| 103 | I represent a failure to decrypt a message. |
| 104 | |
| 105 | Usually this means that someone used the wrong key, though it can also |
| 106 | mean that a ciphertext has been modified. |
| 107 | """ |
| 108 | pass |
| 109 | |
| 110 | class Crypto (object): |
| 111 | """ |
| 112 | I represent a symmetric crypto transform. |
| 113 | |
| 114 | There's currently only one transform implemented, which is the obvious |
| 115 | generic-composition construction: given a message m, and keys K0 and K1, we |
| 116 | choose an IV v, and compute: |
| 117 | |
| 118 | * y = v || E(K0, v; m) |
| 119 | * t = M(K1; y) |
| 120 | |
| 121 | The final ciphertext is t || y. |
| 122 | """ |
| 123 | |
| 124 | def __init__(me, c, h, m, ck, mk): |
| 125 | """ |
| 126 | Initialize the Crypto object with a given algorithm selection and keys. |
| 127 | |
| 128 | We need a GCipher subclass C, a GHash subclass H, a GMAC subclass M, and |
| 129 | keys CK and MK for C and M respectively. |
| 130 | """ |
| 131 | me.c = c(ck) |
| 132 | me.m = m(mk) |
| 133 | me.h = h |
| 134 | |
| 135 | def encrypt(me, pt): |
| 136 | """ |
| 137 | Encrypt the message PT and return the resulting ciphertext. |
| 138 | """ |
| 139 | blksz = me.c.__class__.blksz |
| 140 | b = _C.WriteBuffer() |
| 141 | if blksz: |
| 142 | iv = _C.rand.block(blksz) |
| 143 | me.c.setiv(iv) |
| 144 | b.put(iv) |
| 145 | b.put(me.c.encrypt(pt)) |
| 146 | t = me.m().hash(b).done() |
| 147 | return t + str(buffer(b)) |
| 148 | |
| 149 | def decrypt(me, ct): |
| 150 | """ |
| 151 | Decrypt the ciphertext CT, returning the plaintext. |
| 152 | |
| 153 | Raises DecryptError if anything goes wrong. |
| 154 | """ |
| 155 | blksz = me.c.__class__.blksz |
| 156 | tagsz = me.m.__class__.tagsz |
| 157 | b = _C.ReadBuffer(ct) |
| 158 | t = b.get(tagsz) |
| 159 | h = me.m() |
| 160 | if blksz: |
| 161 | iv = b.get(blksz) |
| 162 | me.c.setiv(iv) |
| 163 | h.hash(iv) |
| 164 | x = b.get(b.left) |
| 165 | h.hash(x) |
| 166 | if t != h.done(): raise DecryptError |
| 167 | return me.c.decrypt(x) |
| 168 | |
| 169 | class PPK (Crypto): |
| 170 | """ |
| 171 | I represent a crypto transform whose keys are derived from a passphrase. |
| 172 | |
| 173 | The password is salted and hashed; the salt is available as the `salt' |
| 174 | attribute. |
| 175 | """ |
| 176 | |
| 177 | def __init__(me, pp, c, h, m, salt = None): |
| 178 | """ |
| 179 | Initialize the PPK object with a passphrase and algorithm selection. |
| 180 | |
| 181 | We want a passphrase PP, a GCipher subclass C, a GHash subclass H, a GMAC |
| 182 | subclass M, and a SALT. The SALT may be None, if we're generating new |
| 183 | keys, indicating that a salt should be chosen randomly. |
| 184 | """ |
| 185 | if not salt: salt = _C.rand.block(h.hashsz) |
| 186 | tag = '%s\0%s' % (pp, salt) |
| 187 | Crypto.__init__(me, c, h, m, |
| 188 | h().hash('cipher:' + tag).done(), |
| 189 | h().hash('mac:' + tag).done()) |
| 190 | me.salt = salt |
| 191 | |
| 192 | ###-------------------------------------------------------------------------- |
| 193 | ### Backend storage. |
| 194 | |
| 195 | class StorageBackendRefusal (Exception): |
| 196 | """ |
| 197 | I signify that a StorageBackend subclass has refused to open a file. |
| 198 | |
| 199 | This is used by the StorageBackend.open class method. |
| 200 | """ |
| 201 | pass |
| 202 | |
| 203 | class StorageBackendClass (type): |
| 204 | """ |
| 205 | I am a metaclass for StorageBackend classes. |
| 206 | |
| 207 | My main feature is that I register my concrete instances (with a `NAME' |
| 208 | which is not `None') with the StorageBackend class. |
| 209 | """ |
| 210 | def __init__(me, name, supers, dict): |
| 211 | """ |
| 212 | Register a new concrete StorageBackend subclass. |
| 213 | """ |
| 214 | super(StorageBackendClass, me).__init__(name, supers, dict) |
| 215 | if me.NAME is not None: StorageBackend.register_concrete_subclass(me) |
| 216 | |
| 217 | class StorageBackend (object): |
| 218 | """ |
| 219 | I provide basic protocol for password storage backends. |
| 220 | |
| 221 | I'm an abstract class: you want one of my subclasses if you actually want |
| 222 | to do something useful. But I maintain a list of my subclasses and can |
| 223 | choose an appropriate one to open a database file you've found lying about. |
| 224 | |
| 225 | Backends are responsible for storing and retrieving stuff, but not for the |
| 226 | cryptographic details. Backends need to store two kinds of information: |
| 227 | |
| 228 | * metadata, consisting of a number of property names and their values; |
| 229 | and |
| 230 | |
| 231 | * password mappings, consisting of a number of binary labels and |
| 232 | payloads. |
| 233 | |
| 234 | Backends need to implement the following ordinary methods. See the calling |
| 235 | methods for details of the subclass responsibilities. |
| 236 | |
| 237 | BE._create(FILE) Create a new database in FILE; used by `create'. |
| 238 | |
| 239 | BE._open(FILE, WRITEP) |
| 240 | Open the existing database FILE; used by `open'. |
| 241 | |
| 242 | BE._close(ABRUPTP) Close the database, freeing up any resources. If |
| 243 | ABRUPTP then don't try to commit changes. |
| 244 | |
| 245 | BE._get_meta(NAME, DEFAULT) |
| 246 | Return the value of the metadata item with the given |
| 247 | NAME, or DEFAULT if it doesn't exist; used by |
| 248 | `get_meta'. |
| 249 | |
| 250 | BE._put_meta(NAME, VALUE) |
| 251 | Set the VALUE of the metadata item with the given |
| 252 | NAME, creating one if necessary; used by `put_meta'. |
| 253 | |
| 254 | BE._del_meta(NAME) Forget the metadata item with the given NAME; raise |
| 255 | `KeyError' if there is no such item; used by |
| 256 | `del_meta'. |
| 257 | |
| 258 | BE._iter_meta() Return an iterator over the metadata (NAME, VALUE) |
| 259 | pairs; used by `iter_meta'. |
| 260 | |
| 261 | BE._get_passwd(LABEL) |
| 262 | Return the password payload stored with the (binary) |
| 263 | LABEL; used by `get_passwd'. |
| 264 | |
| 265 | BE._put_passwd(LABEL, PAYLOAD) |
| 266 | Associate the (binary) PAYLOAD with the LABEL, |
| 267 | forgetting any previous payload for that LABEL; used |
| 268 | by `put_passwd'. |
| 269 | |
| 270 | BE._del_passwd(LABEL) Forget the password record with the given LABEL; used |
| 271 | by `_del_passwd'. |
| 272 | |
| 273 | BE._iter_passwds() Return an iterator over the password (LABEL, PAYLOAD) |
| 274 | pairs; used by `iter_passwds'. |
| 275 | |
| 276 | Also, concrete subclasses should define the following class attributes. |
| 277 | |
| 278 | NAME The name of the backend, so that the user can select |
| 279 | it when creating a new database. |
| 280 | |
| 281 | PRIO An integer priority: backends are tried in decreasing |
| 282 | priority order when opening an existing database. |
| 283 | """ |
| 284 | |
| 285 | __metaclass__ = StorageBackendClass |
| 286 | NAME = None |
| 287 | PRIO = 10 |
| 288 | |
| 289 | ## The registry of subclasses. |
| 290 | CLASSES = {} |
| 291 | |
| 292 | FAIL = ['FAIL'] |
| 293 | |
| 294 | @staticmethod |
| 295 | def register_concrete_subclass(sub): |
| 296 | """Register a concrete subclass, so that `open' can try it.""" |
| 297 | StorageBackend.CLASSES[sub.NAME] = sub |
| 298 | |
| 299 | @staticmethod |
| 300 | def byname(name): |
| 301 | """ |
| 302 | Return the concrete subclass with the given NAME. |
| 303 | |
| 304 | Raise `KeyError' if the name isn't found. |
| 305 | """ |
| 306 | return StorageBackend.CLASSES[name] |
| 307 | |
| 308 | @staticmethod |
| 309 | def classes(): |
| 310 | """Return an iterator over the concrete subclasses.""" |
| 311 | return StorageBackend.CLASSES.itervalues() |
| 312 | |
| 313 | @staticmethod |
| 314 | def open(file, writep = False): |
| 315 | """Open a database FILE, using some appropriate backend.""" |
| 316 | _OS.stat(file) |
| 317 | for cls in sorted(StorageBackend.CLASSES.values(), reverse = True, |
| 318 | key = lambda cls: cls.PRIO): |
| 319 | try: return cls(file, writep) |
| 320 | except StorageBackendRefusal: pass |
| 321 | raise StorageBackendRefusal |
| 322 | |
| 323 | @classmethod |
| 324 | def create(cls, file): |
| 325 | """ |
| 326 | Create a new database in the named FILE, using this backend. |
| 327 | |
| 328 | Subclasses must implement the `_create' instance method. |
| 329 | """ |
| 330 | return cls(writep = True, _magic = lambda me: me._create(file)) |
| 331 | |
| 332 | def __init__(me, file = None, writep = False, _magic = None, *args, **kw): |
| 333 | """ |
| 334 | Main constructor. |
| 335 | |
| 336 | Subclasses are not, in general, expected to override this: there's a |
| 337 | somewhat hairy protocol between the constructor and some of the class |
| 338 | methods. Instead, the main hook for customization is the subclass's |
| 339 | `_open' method, which is invoked in the usual case. |
| 340 | """ |
| 341 | super(StorageBackend, me).__init__(*args, **kw) |
| 342 | if me.NAME is None: raise ValueError, 'abstract class' |
| 343 | if _magic is not None: _magic(me) |
| 344 | elif file is None: raise ValueError, 'missing file parameter' |
| 345 | else: me._open(file, writep) |
| 346 | me._writep = writep |
| 347 | me._livep = True |
| 348 | |
| 349 | def close(me, abruptp = False): |
| 350 | """ |
| 351 | Close the database. |
| 352 | |
| 353 | It is harmless to attempt to close a database which has been closed |
| 354 | already. Calls the subclass's `_close' method. |
| 355 | """ |
| 356 | if me._livep: |
| 357 | me._livep = False |
| 358 | me._close(abruptp) |
| 359 | |
| 360 | ## Utilities. |
| 361 | |
| 362 | def _check_live(me): |
| 363 | """Raise an error if the receiver has been closed.""" |
| 364 | if not me._livep: raise ValueError, 'database is closed' |
| 365 | |
| 366 | def _check_write(me): |
| 367 | """Raise an error if the receiver is not open for writing.""" |
| 368 | me._check_live() |
| 369 | if not me._writep: raise ValueError, 'database is read-only' |
| 370 | |
| 371 | def _check_meta_name(me, name): |
| 372 | """ |
| 373 | Raise an error unless NAME is a valid name for a metadata item. |
| 374 | |
| 375 | Metadata names may not start with `$': such names are reserved for |
| 376 | password storage. |
| 377 | """ |
| 378 | if name.startswith('$'): |
| 379 | raise ValueError, "invalid metadata key `%s'" % name |
| 380 | |
| 381 | ## Context protocol. |
| 382 | |
| 383 | def __enter__(me): |
| 384 | """Context protocol: make sure the database is closed on exit.""" |
| 385 | return me |
| 386 | def __exit__(me, exctype, excvalue, exctb): |
| 387 | """Context protocol: see `__enter__'.""" |
| 388 | me.close(excvalue is not None) |
| 389 | |
| 390 | ## Metadata. |
| 391 | |
| 392 | def get_meta(me, name, default = FAIL): |
| 393 | """ |
| 394 | Fetch the value for the metadata item NAME. |
| 395 | |
| 396 | If no such item exists, then return DEFAULT if that was set; otherwise |
| 397 | raise a `KeyError'. |
| 398 | |
| 399 | This calls the subclass's `_get_meta' method, which should return the |
| 400 | requested item or return the given DEFAULT value. It may assume that the |
| 401 | name is valid and the database is open. |
| 402 | """ |
| 403 | me._check_meta_name(name) |
| 404 | me._check_live() |
| 405 | value = me._get_meta(name, default) |
| 406 | if value is StorageBackend.FAIL: raise KeyError, name |
| 407 | return value |
| 408 | |
| 409 | def put_meta(me, name, value): |
| 410 | """ |
| 411 | Store VALUE in the metadata item called NAME. |
| 412 | |
| 413 | This calls the subclass's `_put_meta' method, which may assume that the |
| 414 | name is valid and the database is open for writing. |
| 415 | """ |
| 416 | me._check_meta_name(name) |
| 417 | me._check_write() |
| 418 | me._put_meta(name, value) |
| 419 | |
| 420 | def del_meta(me, name): |
| 421 | """ |
| 422 | Forget about the metadata item with the given NAME. |
| 423 | |
| 424 | This calls the subclass's `_del_meta' method, which may assume that the |
| 425 | name is valid and the database is open for writing. |
| 426 | """ |
| 427 | me._check_meta_name(name) |
| 428 | me._check_write() |
| 429 | me._del_meta(name) |
| 430 | |
| 431 | def iter_meta(me): |
| 432 | """ |
| 433 | Return an iterator over the name/value metadata items. |
| 434 | |
| 435 | This calls the subclass's `_iter_meta' method, which may assume that the |
| 436 | database is open. |
| 437 | """ |
| 438 | me._check_live() |
| 439 | return me._iter_meta() |
| 440 | |
| 441 | def get_passwd(me, label): |
| 442 | """ |
| 443 | Fetch and return the payload stored with the (opaque, binary) LABEL. |
| 444 | |
| 445 | If there is no such payload then raise `KeyError'. |
| 446 | |
| 447 | This calls the subclass's `_get_passwd' method, which may assume that the |
| 448 | database is open. |
| 449 | """ |
| 450 | me._check_live() |
| 451 | return me._get_passwd(label) |
| 452 | |
| 453 | def put_passwd(me, label, payload): |
| 454 | """ |
| 455 | Associate the (opaque, binary) PAYLOAD with the (opaque, binary) LABEL. |
| 456 | |
| 457 | Any previous payload for LABEL is forgotten. |
| 458 | |
| 459 | This calls the subclass's `_put_passwd' method, which may assume that the |
| 460 | database is open for writing. |
| 461 | """ |
| 462 | me._check_write() |
| 463 | me._put_passwd(label, payload) |
| 464 | |
| 465 | def del_passwd(me, label): |
| 466 | """ |
| 467 | Forget any PAYLOAD associated with the (opaque, binary) LABEL. |
| 468 | |
| 469 | If there is no such payload then raise `KeyError'. |
| 470 | |
| 471 | This calls the subclass's `_del_passwd' method, which may assume that the |
| 472 | database is open for writing. |
| 473 | """ |
| 474 | me._check_write() |
| 475 | me._del_passwd(label, payload) |
| 476 | |
| 477 | def iter_passwds(me): |
| 478 | """ |
| 479 | Return an iterator over the stored password label/payload pairs. |
| 480 | |
| 481 | This calls the subclass's `_iter_passwds' method, which may assume that |
| 482 | the database is open. |
| 483 | """ |
| 484 | me._check_live() |
| 485 | return me._iter_passwds() |
| 486 | |
| 487 | try: import gdbm as _G |
| 488 | except ImportError: pass |
| 489 | else: |
| 490 | class GDBMStorageBackend (StorageBackend): |
| 491 | """ |
| 492 | My instances store password data in a GDBM database. |
| 493 | |
| 494 | Metadata and password entries are mixed into the same database. The key |
| 495 | for a metadata item is simply its name; the key for a password entry is |
| 496 | the entry's label prefixed by `$', since we're guaranteed that no |
| 497 | metadata item name begins with `$'. |
| 498 | """ |
| 499 | |
| 500 | NAME = 'gdbm' |
| 501 | |
| 502 | def _open(me, file, writep): |
| 503 | try: me._db = _G.open(file, writep and 'w' or 'r') |
| 504 | except _G.error, e: raise StorageBackendRefusal, e |
| 505 | |
| 506 | def _create(me, file): |
| 507 | me._db = _G.open(file, 'n', 0600) |
| 508 | |
| 509 | def _close(me, abruptp): |
| 510 | me._db.close() |
| 511 | me._db = None |
| 512 | |
| 513 | def _get_meta(me, name, default): |
| 514 | try: return me._db[name] |
| 515 | except KeyError: return default |
| 516 | |
| 517 | def _put_meta(me, name, value): |
| 518 | me._db[name] = value |
| 519 | |
| 520 | def _del_meta(me, name): |
| 521 | del me._db[name] |
| 522 | |
| 523 | def _iter_meta(me): |
| 524 | k = me._db.firstkey() |
| 525 | while k is not None: |
| 526 | if not k.startswith('$'): yield k, me._db[k] |
| 527 | k = me._db.nextkey(k) |
| 528 | |
| 529 | def _get_passwd(me, label): |
| 530 | return me._db['$' + label] |
| 531 | |
| 532 | def _put_passwd(me, label, payload): |
| 533 | me._db['$' + label] = payload |
| 534 | |
| 535 | def _del_passwd(me, label): |
| 536 | del me._db['$' + label] |
| 537 | |
| 538 | def _iter_passwds(me): |
| 539 | k = me._db.firstkey() |
| 540 | while k is not None: |
| 541 | if k.startswith('$'): yield k[1:], me._db[k] |
| 542 | k = me._db.nextkey(k) |
| 543 | |
| 544 | try: import sqlite3 as _Q |
| 545 | except ImportError: pass |
| 546 | else: |
| 547 | class SQLiteStorageBackend (StorageBackend): |
| 548 | """ |
| 549 | I represent a password database stored in SQLite. |
| 550 | |
| 551 | Metadata and password items are stored in separate tables, so there's no |
| 552 | conflict. Some additional metadata is stored in the `meta' table, with |
| 553 | names beginning with `$' so as not to conflict with clients: |
| 554 | |
| 555 | $version The schema version of the table. |
| 556 | """ |
| 557 | |
| 558 | NAME = 'sqlite' |
| 559 | VERSION = 0 |
| 560 | |
| 561 | def _open(me, file, writep): |
| 562 | try: |
| 563 | me._db = _Q.connect(file) |
| 564 | ver = me._query_scalar( |
| 565 | "SELECT value FROM meta WHERE name = '$version'", |
| 566 | "version check") |
| 567 | except (_Q.DatabaseError, _Q.OperationalError), e: |
| 568 | raise StorageBackendRefusal, e |
| 569 | if ver is None: raise ValueError, 'database broken (missing $version)' |
| 570 | elif ver < me.VERSION: me._upgrade(ver) |
| 571 | elif ver > me.VERSION: |
| 572 | raise ValueError, 'unknown database schema version (%d > %d)' % \ |
| 573 | (ver, me.VERSION) |
| 574 | |
| 575 | def _create(me, file): |
| 576 | fd = _OS.open(file, _OS.O_WRONLY | _OS.O_CREAT | _OS.O_EXCL, 0600) |
| 577 | _OS.close(fd) |
| 578 | try: |
| 579 | me._db = _Q.connect(file) |
| 580 | c = me._db.cursor() |
| 581 | c.execute(""" |
| 582 | CREATE TABLE meta ( |
| 583 | name TEXT PRIMARY KEY NOT NULL, |
| 584 | value BLOB NOT NULL); |
| 585 | """) |
| 586 | c.execute(""" |
| 587 | CREATE TABLE passwd ( |
| 588 | label BLOB PRIMARY KEY NOT NULL, |
| 589 | payload BLOB NOT NULL); |
| 590 | """) |
| 591 | c.execute(""" |
| 592 | INSERT INTO meta (name, value) VALUES ('$version', ?); |
| 593 | """, [me.VERSION]) |
| 594 | except: |
| 595 | try: _OS.unlink(file) |
| 596 | except OSError: pass |
| 597 | raise |
| 598 | |
| 599 | def _upgrade(me, ver): |
| 600 | """Upgrade the database from schema version VER.""" |
| 601 | assert False, 'how embarrassing' |
| 602 | |
| 603 | def _close(me, abruptp): |
| 604 | if not abruptp: me._db.commit() |
| 605 | me._db.close() |
| 606 | me._db = None |
| 607 | |
| 608 | def _fetch_scalar(me, c, what, default = None): |
| 609 | try: row = next(c) |
| 610 | except StopIteration: val = default |
| 611 | else: val, = row |
| 612 | try: row = next(c) |
| 613 | except StopIteration: pass |
| 614 | else: raise ValueError, 'multiple matching records for %s' % what |
| 615 | return val |
| 616 | |
| 617 | def _query_scalar(me, query, what, default = None, args = []): |
| 618 | c = me._db.cursor() |
| 619 | c.execute(query, args) |
| 620 | return me._fetch_scalar(c, what, default) |
| 621 | |
| 622 | def _get_meta(me, name, default): |
| 623 | v = me._query_scalar("SELECT value FROM meta WHERE name = ?", |
| 624 | "metadata item `%s'" % name, |
| 625 | default = default, args = [name]) |
| 626 | if v is default: return v |
| 627 | else: return str(v) |
| 628 | |
| 629 | def _put_meta(me, name, value): |
| 630 | c = me._db.cursor() |
| 631 | c.execute("INSERT OR REPLACE INTO meta (name, value) VALUES (?, ?)", |
| 632 | [name, buffer(value)]) |
| 633 | |
| 634 | def _del_meta(me, name): |
| 635 | c = me._db.cursor() |
| 636 | c.execute("DELETE FROM meta WHERE name = ?", [name]) |
| 637 | if not c.rowcount: raise KeyError, name |
| 638 | |
| 639 | def _iter_meta(me): |
| 640 | c = me._db.cursor() |
| 641 | c.execute("SELECT name, value FROM meta WHERE name NOT LIKE '$%'") |
| 642 | for k, v in c: yield k, str(v) |
| 643 | |
| 644 | def _get_passwd(me, label): |
| 645 | pld = me._query_scalar("SELECT payload FROM passwd WHERE label = ?", |
| 646 | "password", default = None, |
| 647 | args = [buffer(label)]) |
| 648 | if pld is None: raise KeyError, label |
| 649 | return str(pld) |
| 650 | |
| 651 | def _put_passwd(me, label, payload): |
| 652 | c = me._db.cursor() |
| 653 | c.execute("INSERT OR REPLACE INTO passwd (label, payload) " |
| 654 | "VALUES (?, ?)", |
| 655 | [buffer(label), buffer(payload)]) |
| 656 | |
| 657 | def _del_passwd(me, label): |
| 658 | c = me._db.cursor() |
| 659 | c.execute("DELETE FROM passwd WHERE label = ?", [label]) |
| 660 | if not c.rowcount: raise KeyError, label |
| 661 | |
| 662 | def _iter_passwds(me): |
| 663 | c = me._db.cursor() |
| 664 | c.execute("SELECT label, payload FROM passwd") |
| 665 | for k, v in c: yield str(k), str(v) |
| 666 | |
| 667 | class PlainTextBackend (StorageBackend): |
| 668 | """ |
| 669 | I'm a utility base class for storage backends which use plain text files. |
| 670 | |
| 671 | I provide subclasses with the following capabilities. |
| 672 | |
| 673 | * Creating files, with given modes, optionally ensuring that the file |
| 674 | doesn't exist already. |
| 675 | |
| 676 | * Parsing flat text files, checking leading magic, skipping comments, and |
| 677 | providing standard encodings of troublesome characters and binary |
| 678 | strings in metadata and password records. See below. |
| 679 | |
| 680 | * Maintenance of metadata and password records in in-memory dictionaries, |
| 681 | with ready implementations of the necessary StorageBackend subclass |
| 682 | responsibility methods. (Subclasses can override these if they want to |
| 683 | make different arrangements.) |
| 684 | |
| 685 | Metadata records are written with an optional prefix string chosen by the |
| 686 | caller, followed by a `NAME=VALUE' pair. The NAME is form-urlencoded and |
| 687 | prefixed with `!' if it contains strange characters; the VALUE is base64- |
| 688 | encoded (without the pointless trailing `=' padding) and prefixed with `?' |
| 689 | if necessary. |
| 690 | |
| 691 | Password records are written with an optional prefix string chosen by the |
| 692 | caller, followed by a LABEL=PAYLOAD pair, both of which are base64-encoded |
| 693 | (without padding). |
| 694 | |
| 695 | The following attributes are available for subclasses: |
| 696 | |
| 697 | _meta Dictionary mapping metadata item names to their values. |
| 698 | Populated by `_parse_meta' and managed by `_get_meta' and |
| 699 | friends. |
| 700 | |
| 701 | _pw Dictionary mapping password labels to encrypted payloads. |
| 702 | Populated by `_parse_passwd' and managed by `_get_passwd' and |
| 703 | friends. |
| 704 | |
| 705 | _dirtyp Boolean: set if either of the dictionaries has been modified. |
| 706 | """ |
| 707 | |
| 708 | def __init__(me, *args, **kw): |
| 709 | """ |
| 710 | Hook for initialization. |
| 711 | |
| 712 | Sets up the published instance attributes. |
| 713 | """ |
| 714 | me._meta = {} |
| 715 | me._pw = {} |
| 716 | me._dirtyp = False |
| 717 | super(PlainTextBackend, me).__init__(*args, **kw) |
| 718 | |
| 719 | def _create_file(me, file, mode = 0600, freshp = False): |
| 720 | """ |
| 721 | Make sure FILE exists, creating it with the given MODE if necessary. |
| 722 | |
| 723 | If FRESHP is true, then make sure the file did not exist previously. |
| 724 | Return a file object for the newly created file. |
| 725 | """ |
| 726 | flags = _OS.O_CREAT | _OS.O_WRONLY |
| 727 | if freshp: flags |= _OS.O_EXCL |
| 728 | else: flags |= _OS.O_TRUNC |
| 729 | fd = _OS.open(file, flags, mode) |
| 730 | return _OS.fdopen(fd, 'w') |
| 731 | |
| 732 | def _mark_dirty(me): |
| 733 | """ |
| 734 | Set the `_dirtyp' flag. |
| 735 | |
| 736 | Subclasses might find it useful to intercept this method. |
| 737 | """ |
| 738 | me._dirtyp = True |
| 739 | |
| 740 | def _eqsplit(me, line): |
| 741 | """ |
| 742 | Extract the KEY, VALUE pair from a LINE of the form `KEY=VALUE'. |
| 743 | |
| 744 | Raise `ValueError' if there is no `=' in the LINE. |
| 745 | """ |
| 746 | eq = line.index('=') |
| 747 | return line[:eq], line[eq + 1:] |
| 748 | |
| 749 | def _parse_file(me, file, magic = None): |
| 750 | """ |
| 751 | Parse a FILE. |
| 752 | |
| 753 | Specifically: |
| 754 | |
| 755 | * Raise `StorageBackendRefusal' if that the first line doesn't match |
| 756 | MAGIC (if provided). MAGIC should not contain the terminating |
| 757 | newline. |
| 758 | |
| 759 | * Ignore comments (beginning `#') and blank lines. |
| 760 | |
| 761 | * Call `_parse_line' (provided by the subclass) for other lines. |
| 762 | """ |
| 763 | with open(file, 'r') as f: |
| 764 | if magic is not None: |
| 765 | if f.readline().rstrip('\n') != magic: raise StorageBackendRefusal |
| 766 | for line in f: |
| 767 | line = line.rstrip('\n') |
| 768 | if not line or line.startswith('#'): continue |
| 769 | me._parse_line(line) |
| 770 | |
| 771 | def _write_file(me, file, writebody, mode = 0600, magic = None): |
| 772 | """ |
| 773 | Update FILE atomically. |
| 774 | |
| 775 | The newly created file will have the given MODE. If MAGIC is given, then |
| 776 | write that as the first line. Calls WRITEBODY(F) to write the main body |
| 777 | of the file where F is a file object for the new file. |
| 778 | """ |
| 779 | new = file + '.new' |
| 780 | with me._create_file(new, mode) as f: |
| 781 | if magic is not None: f.write(magic + '\n') |
| 782 | writebody(f) |
| 783 | _OS.rename(new, file) |
| 784 | |
| 785 | def _parse_meta(me, line): |
| 786 | """Parse LINE as a metadata NAME=VALUE pair, and updates `_meta'.""" |
| 787 | k, v = me._eqsplit(line) |
| 788 | me._meta[_dec_metaname(k)] = _dec_metaval(v) |
| 789 | |
| 790 | def _write_meta(me, f, prefix = ''): |
| 791 | """Write the metadata records to F, each with the given PREFIX.""" |
| 792 | f.write('\n## Metadata.\n') |
| 793 | for k, v in me._meta.iteritems(): |
| 794 | f.write('%s%s=%s\n' % (prefix, _enc_metaname(k), _enc_metaval(v))) |
| 795 | |
| 796 | def _get_meta(me, name, default): |
| 797 | return me._meta.get(name, default) |
| 798 | def _put_meta(me, name, value): |
| 799 | me._mark_dirty() |
| 800 | me._meta[name] = value |
| 801 | def _del_meta(me, name): |
| 802 | me._mark_dirty() |
| 803 | del me._meta[name] |
| 804 | def _iter_meta(me): |
| 805 | return me._meta.iteritems() |
| 806 | |
| 807 | def _parse_passwd(me, line): |
| 808 | """Parse LINE as a password LABEL=PAYLOAD pair, and updates `_pw'.""" |
| 809 | k, v = me._eqsplit(line) |
| 810 | me._pw[_unb64(k)] = _unb64(v) |
| 811 | |
| 812 | def _write_passwd(me, f, prefix = ''): |
| 813 | """Write the password records to F, each with the given PREFIX.""" |
| 814 | f.write('\n## Password data.\n') |
| 815 | for k, v in me._pw.iteritems(): |
| 816 | f.write('%s%s=%s\n' % (prefix, _b64(k), _b64(v))) |
| 817 | |
| 818 | def _get_passwd(me, label): |
| 819 | return me._pw[str(label)] |
| 820 | def _put_passwd(me, label, payload): |
| 821 | me._mark_dirty() |
| 822 | me._pw[str(label)] = payload |
| 823 | def _del_passwd(me, label): |
| 824 | me._mark_dirty() |
| 825 | del me._pw[str(label)] |
| 826 | def _iter_passwds(me): |
| 827 | return me._pw.iteritems() |
| 828 | |
| 829 | class FlatFileStorageBackend (PlainTextBackend): |
| 830 | """ |
| 831 | I maintain a password database in a plain text file. |
| 832 | |
| 833 | The text file consists of lines, as follows. |
| 834 | |
| 835 | * Empty lines, and lines beginning with `#' (in the leftmost column only) |
| 836 | are ignored. |
| 837 | |
| 838 | * Lines of the form `$LABEL=PAYLOAD' store password data. Both LABEL and |
| 839 | PAYLOAD are base64-encoded, without `=' padding. |
| 840 | |
| 841 | * Lines of the form `NAME=VALUE' store metadata. If the NAME contains |
| 842 | characters other than alphanumerics, hyphens, underscores, and colons, |
| 843 | then it is form-urlencoded, and prefixed wth `!'. If the VALUE |
| 844 | contains such characters, then it is base64-encoded, without `=' |
| 845 | padding, and prefixed with `?'. |
| 846 | |
| 847 | * Other lines are erroneous. |
| 848 | |
| 849 | The file is rewritten from scratch when it's changed: any existing |
| 850 | commentary is lost, and items may be reordered. There is no file locking, |
| 851 | but the file is updated atomically, by renaming. |
| 852 | |
| 853 | It is expected that the FlatFileStorageBackend is used mostly for |
| 854 | diagnostics and transfer, rather than for a live system. |
| 855 | """ |
| 856 | |
| 857 | NAME = 'flat' |
| 858 | PRIO = 0 |
| 859 | MAGIC = '### pwsafe password database' |
| 860 | |
| 861 | def _open(me, file, writep): |
| 862 | if not _OS.path.isfile(file): raise StorageBackendRefusal |
| 863 | me._parse_file(file, magic = me.MAGIC) |
| 864 | def _parse_line(me, line): |
| 865 | if line.startswith('$'): me._parse_passwd(line[1:]) |
| 866 | else: me._parse_meta(line) |
| 867 | |
| 868 | def _create(me, file): |
| 869 | with me._create_file(file, freshp = True) as f: pass |
| 870 | me._file = file |
| 871 | me._mark_dirty() |
| 872 | |
| 873 | def _close(me, abruptp): |
| 874 | if not abruptp and me._dirtyp: |
| 875 | me._write_file(me._file, me._write_body, magic = me.MAGIC) |
| 876 | |
| 877 | def _write_body(me, f): |
| 878 | me._write_meta(f) |
| 879 | me._write_passwd(f, '$') |
| 880 | |
| 881 | class DirectoryStorageBackend (PlainTextBackend): |
| 882 | """ |
| 883 | I maintain a password database in a directory, with one file per password. |
| 884 | |
| 885 | This makes password databases easy to maintain in a revision-control system |
| 886 | such as Git. |
| 887 | |
| 888 | The directory is structured as follows. |
| 889 | |
| 890 | dir/meta Contains metadata, similar to the `FlatFileBackend'. |
| 891 | |
| 892 | dir/pw/LABEL Contains the (raw binary) payload for the given password |
| 893 | LABEL (base64-encoded, without the useless `=' padding, and |
| 894 | with `/' replaced by `.'). |
| 895 | |
| 896 | dir/tmp/ Contains temporary files used by the implementation. |
| 897 | """ |
| 898 | |
| 899 | NAME = 'dir' |
| 900 | METAMAGIC = '### pwsafe password directory metadata' |
| 901 | |
| 902 | def _open(me, file, writep): |
| 903 | if not _OS.path.isdir(file) or \ |
| 904 | not _OS.path.isdir(_OS.path.join(file, 'pw')) or \ |
| 905 | not _OS.path.isdir(_OS.path.join(file, 'tmp')) or \ |
| 906 | not _OS.path.isfile(_OS.path.join(file, 'meta')): |
| 907 | raise StorageBackendRefusal |
| 908 | me._dir = file |
| 909 | me._parse_file(_OS.path.join(file, 'meta'), magic = me.METAMAGIC) |
| 910 | def _parse_line(me, line): |
| 911 | me._parse_meta(line) |
| 912 | |
| 913 | def _create(me, file): |
| 914 | _OS.mkdir(file, 0700) |
| 915 | _OS.mkdir(_OS.path.join(file, 'pw'), 0700) |
| 916 | _OS.mkdir(_OS.path.join(file, 'tmp'), 0700) |
| 917 | me._mark_dirty() |
| 918 | me._dir = file |
| 919 | |
| 920 | def _close(me, abruptp): |
| 921 | if not abruptp and me._dirtyp: |
| 922 | me._write_file(_OS.path.join(me._dir, 'meta'), |
| 923 | me._write_meta, magic = me.METAMAGIC) |
| 924 | |
| 925 | def _pwfile(me, label, dir = 'pw'): |
| 926 | return _OS.path.join(me._dir, dir, _b64(label).replace('/', '.')) |
| 927 | def _get_passwd(me, label): |
| 928 | try: |
| 929 | f = open(me._pwfile(label), 'rb') |
| 930 | except (OSError, IOError), e: |
| 931 | if e.errno == _E.ENOENT: raise KeyError, label |
| 932 | else: raise |
| 933 | with f: return f.read() |
| 934 | def _put_passwd(me, label, payload): |
| 935 | new = me._pwfile(label, 'tmp') |
| 936 | fd = _OS.open(new, _OS.O_WRONLY | _OS.O_CREAT | _OS.O_TRUNC, 0600) |
| 937 | _OS.close(fd) |
| 938 | with open(new, 'wb') as f: f.write(payload) |
| 939 | _OS.rename(new, me._pwfile(label)) |
| 940 | def _del_passwd(me, label): |
| 941 | try: |
| 942 | _OS.remove(me._pwfile(label)) |
| 943 | except (OSError, IOError), e: |
| 944 | if e == _E.ENOENT: raise KeyError, label |
| 945 | else: raise |
| 946 | def _iter_passwds(me): |
| 947 | pw = _OS.path.join(me._dir, 'pw') |
| 948 | for i in _OS.listdir(pw): |
| 949 | with open(_OS.path.join(pw, i), 'rb') as f: pld = f.read() |
| 950 | yield _unb64(i.replace('.', '/')), pld |
| 951 | |
| 952 | ###-------------------------------------------------------------------------- |
| 953 | ### Password storage. |
| 954 | |
| 955 | class PW (object): |
| 956 | """ |
| 957 | I represent a secure (ish) password store. |
| 958 | |
| 959 | I can store short secrets, associated with textual names, in a way which |
| 960 | doesn't leak too much information about them. |
| 961 | |
| 962 | I implement (some of) the Python mapping protocol. |
| 963 | |
| 964 | I keep track of everything using a StorageBackend object. This contains |
| 965 | password entries, identified by cryptographic labels, and a number of |
| 966 | metadata items. |
| 967 | |
| 968 | cipher Names the Catacomb cipher selected. |
| 969 | |
| 970 | hash Names the Catacomb hash function selected. |
| 971 | |
| 972 | key Cipher and MAC keys, each prefixed by a 16-bit big-endian |
| 973 | length and concatenated, encrypted using the master |
| 974 | passphrase. |
| 975 | |
| 976 | mac Names the Catacomb message authentication code selected. |
| 977 | |
| 978 | magic A magic string for obscuring password tag names. |
| 979 | |
| 980 | salt The salt for hashing the passphrase. |
| 981 | |
| 982 | tag The master passphrase's tag, for the Pixie's benefit. |
| 983 | |
| 984 | Password entries are assigned labels of the form `$' || H(MAGIC || TAG); |
| 985 | the corresponding value consists of a pair (TAG, PASSWD), prefixed with |
| 986 | 16-bit lengths, concatenated, padded to a multiple of 256 octets, and |
| 987 | encrypted using the stored keys. |
| 988 | """ |
| 989 | |
| 990 | def __init__(me, file, writep = False): |
| 991 | """ |
| 992 | Initialize a PW object from the database in FILE. |
| 993 | |
| 994 | If WRITEP is false (the default) then the database is opened read-only; |
| 995 | if true then it may be written. Requests the database password from the |
| 996 | Pixie, which may cause interaction. |
| 997 | """ |
| 998 | |
| 999 | ## Open the database. |
| 1000 | me.db = StorageBackend.open(file, writep) |
| 1001 | |
| 1002 | ## Find out what crypto to use. |
| 1003 | c = _C.gcciphers[me.db.get_meta('cipher')] |
| 1004 | h = _C.gchashes[me.db.get_meta('hash')] |
| 1005 | m = _C.gcmacs[me.db.get_meta('mac')] |
| 1006 | |
| 1007 | ## Request the passphrase and extract the master keys. |
| 1008 | tag = me.db.get_meta('tag') |
| 1009 | ppk = PPK(_C.ppread(tag), c, h, m, me.db.get_meta('salt')) |
| 1010 | try: |
| 1011 | b = _C.ReadBuffer(ppk.decrypt(me.db.get_meta('key'))) |
| 1012 | except DecryptError: |
| 1013 | _C.ppcancel(tag) |
| 1014 | raise |
| 1015 | me.ck = b.getblk16() |
| 1016 | me.mk = b.getblk16() |
| 1017 | if not b.endp: raise ValueError, 'trailing junk' |
| 1018 | |
| 1019 | ## Set the key, and stash it and the tag-hashing secret. |
| 1020 | me.k = Crypto(c, h, m, me.ck, me.mk) |
| 1021 | me.magic = me.k.decrypt(me.db.get_meta('magic')) |
| 1022 | |
| 1023 | @classmethod |
| 1024 | def create(cls, dbcls, file, tag, c, h, m): |
| 1025 | """ |
| 1026 | Create and initialize a new database FILE using StorageBackend DBCLS. |
| 1027 | |
| 1028 | We want a GCipher subclass C, a GHash subclass H, and a GMAC subclass M; |
| 1029 | and a Pixie passphrase TAG. |
| 1030 | |
| 1031 | This doesn't return a working object: it just creates the database file |
| 1032 | and gets out of the way. |
| 1033 | """ |
| 1034 | |
| 1035 | ## Set up the cryptography. |
| 1036 | pp = _C.ppread(tag, _C.PMODE_VERIFY) |
| 1037 | ppk = PPK(pp, c, h, m) |
| 1038 | ck = _C.rand.block(c.keysz.default) |
| 1039 | mk = _C.rand.block(c.keysz.default) |
| 1040 | k = Crypto(c, h, m, ck, mk) |
| 1041 | |
| 1042 | ## Set up and initialize the database. |
| 1043 | kct = ppk.encrypt(_C.WriteBuffer().putblk16(ck).putblk16(mk)) |
| 1044 | with dbcls.create(file) as db: |
| 1045 | db.put_meta('tag', tag) |
| 1046 | db.put_meta('salt', ppk.salt) |
| 1047 | db.put_meta('cipher', c.name) |
| 1048 | db.put_meta('hash', h.name) |
| 1049 | db.put_meta('mac', m.name) |
| 1050 | db.put_meta('key', kct) |
| 1051 | db.put_meta('magic', k.encrypt(_C.rand.block(h.hashsz))) |
| 1052 | |
| 1053 | def keyxform(me, key): |
| 1054 | """Transform the KEY (actually a password tag) into a password label.""" |
| 1055 | return me.k.h().hash(me.magic).hash(key).done() |
| 1056 | |
| 1057 | def changepp(me): |
| 1058 | """ |
| 1059 | Change the database password. |
| 1060 | |
| 1061 | Requests the new password from the Pixie, which will probably cause |
| 1062 | interaction. |
| 1063 | """ |
| 1064 | tag = me.db.get_meta('tag') |
| 1065 | _C.ppcancel(tag) |
| 1066 | ppk = PPK(_C.ppread(tag, _C.PMODE_VERIFY), |
| 1067 | me.k.c.__class__, me.k.h, me.k.m.__class__) |
| 1068 | kct = ppk.encrypt(_C.WriteBuffer().putblk16(me.ck).putblk16(me.mk)) |
| 1069 | me.db.put_meta('key', kct) |
| 1070 | me.db.put_meta('salt', ppk.salt) |
| 1071 | |
| 1072 | def pack(me, key, value): |
| 1073 | """Pack the KEY and VALUE into a ciphertext, and return it.""" |
| 1074 | b = _C.WriteBuffer() |
| 1075 | b.putblk16(key).putblk16(value) |
| 1076 | b.zero(((b.size + 255) & ~255) - b.size) |
| 1077 | return me.k.encrypt(b) |
| 1078 | |
| 1079 | def unpack(me, ct): |
| 1080 | """ |
| 1081 | Unpack a ciphertext CT and return a (KEY, VALUE) pair. |
| 1082 | |
| 1083 | Might raise DecryptError, of course. |
| 1084 | """ |
| 1085 | b = _C.ReadBuffer(me.k.decrypt(ct)) |
| 1086 | key = b.getblk16() |
| 1087 | value = b.getblk16() |
| 1088 | return key, value |
| 1089 | |
| 1090 | ## Mapping protocol. |
| 1091 | |
| 1092 | def __getitem__(me, key): |
| 1093 | """Return the password for the given KEY.""" |
| 1094 | try: return me.unpack(me.db.get_passwd(me.keyxform(key)))[1] |
| 1095 | except KeyError: raise KeyError, key |
| 1096 | |
| 1097 | def __setitem__(me, key, value): |
| 1098 | """Associate the password VALUE with the KEY.""" |
| 1099 | me.db.put_passwd(me.keyxform(key), me.pack(key, value)) |
| 1100 | |
| 1101 | def __delitem__(me, key): |
| 1102 | """Forget all about the KEY.""" |
| 1103 | try: me.db.del_passwd(me.keyxform(key)) |
| 1104 | except KeyError: raise KeyError, key |
| 1105 | |
| 1106 | def __iter__(me): |
| 1107 | """Iterate over the known password tags.""" |
| 1108 | for _, pld in me.db.iter_passwds(): |
| 1109 | yield me.unpack(pld)[0] |
| 1110 | |
| 1111 | ## Context protocol. |
| 1112 | |
| 1113 | def __enter__(me): |
| 1114 | return me |
| 1115 | def __exit__(me, excty, excval, exctb): |
| 1116 | me.db.close(excval is not None) |
| 1117 | |
| 1118 | ###----- That's all, folks -------------------------------------------------- |