1 # Copyright (c) 1999-2001 Jason Gunthorpe <jgg@debian.org>
2 # Copyright (c) 2005 Joey Schulze <joey@infodrom.org>
4 # This program is free software; you can redistribute it and/or modify
5 # it under the terms of the GNU General Public License as published by
6 # the Free Software Foundation; either version 2 of the License, or
7 # (at your option) any later version.
9 # This program is distributed in the hope that it will be useful,
10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 # GNU General Public License for more details.
14 # You should have received a copy of the GNU General Public License
15 # along with this program; if not, write to the Free Software
16 # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 # - gpgm with a status FD being fed keymaterial and other interesting
20 # things does nothing.. If it could ID the keys and stuff over the
21 # status-fd I could decide what to do with them. I would also like it
22 # to report which key it selected for encryption (also if there
23 # were multi-matches..) Being able to detect a key-revoke cert would be
25 # - I would like to be able to fetch the comment and version fields from the
26 # packets so I can tell if a signature is made by pgp2 to enable the
27 # pgp2 encrypting mode.
29 import mimetools, multifile, sys, StringIO, os, tempfile, re;
30 import rfc822, time, fcntl, anydbm
34 # "--load-extension","rsa",
38 "--no-default-keyring",
39 "--secret-keyring", "/dev/null",
42 GPGSigOptions = ["--output","-"];
43 GPGSearchOptions = ["--dry-run","--with-colons","--fingerprint"];
44 GPGEncryptOptions = ["--output","-","--quiet","--always-trust",\
45 "--armor","--encrypt"];
46 GPGEncryptPGP2Options = ["--set-filename","","--rfc1991",\
47 "--load-extension","idea",\
48 "--cipher-algo","idea"] + GPGEncryptOptions;
50 # Replay cutoff times in seconds
51 CleanCutOff = 7*24*60*60;
52 AgeCutOff = 4*24*60*60;
53 FutureCutOff = 3*24*60*60;
55 # Set the keyrings, the input is a list of keyrings
56 def SetKeyrings(Rings):
58 GPGKeyRings.append("--keyring");
59 GPGKeyRings.append(x);
61 # GetClearSig takes an un-seekable email message stream (mimetools.Message)
62 # and returns a standard PGP '---BEGIN PGP SIGNED MESSAGE---' bounded
64 # If this is fed to gpg/pgp it will verify the signature and spit out the
65 # signed text component. Email headers and PGP mime (RFC 2015) is understood
66 # but no effort is made to cull any information outside the PGP boundaries
67 # Please note that in the event of a mime decode the mime headers will be
68 # present in the signature text! The return result is a tuple, the first
69 # element is the text itself the second is a mime flag indicating if the
70 # result should be mime processed after sig checking.
72 # Paranoid will check the message text to make sure that all the plaintext is
73 # in fact signed (bounded by a PGP packet)
74 def GetClearSig(Msg,Paranoid = 0):
76 # See if this is a MIME encoded multipart signed message
77 if Msg.gettype() == "multipart/signed":
78 Boundary = Msg.getparam("boundary");
80 raise Error, "multipart/* without a boundary parameter";
82 # Create the multipart handler. Regrettably their implementation
84 SkMessage = StringIO.StringIO();
85 SkMessage.write(Msg.fp.read());
87 mf = multifile.MultiFile(SkMessage)
88 mf.push(Msg.getparam("boundary"));
90 # Check the first bit of the message..
96 if len(x.strip()) != 0:
97 raise Error,"Unsigned text in message (at start)";
100 # Get the first part of the multipart message
102 raise Error, "Invalid pgp/mime encoding [no section]";
104 # Get the part as a safe seekable stream
105 Signed = StringIO.StringIO();
106 Signed.write(mf.read());
107 InnerMsg = mimetools.Message(Signed);
109 # Make sure it is the right type
110 if InnerMsg.gettype() != "text/plain":
111 raise Error, "Invalid pgp/mime encoding [wrong plaintext type]";
113 # Get the next part of the multipart message
115 raise Error, "Invalid pgp/mime encoding [no section]";
116 InnerMsg = mimetools.Message(mf);
117 if InnerMsg.gettype() != "application/pgp-signature":
118 raise Error, "Invalid pgp/mime encoding [wrong signature type]";
119 Signature = ''.join(mf.readlines())
121 # Check the last bit of the message..
128 if len(x.strip()) != 0:
129 raise Error,"Unsigned text in message (at end)";
132 # Append the PGP boundary header and the signature text to re-form the
133 # original signed block [needs to convert to \r\n]
134 Output = "-----BEGIN PGP SIGNED MESSAGE-----\r\n";
135 # Semi-evil hack to get the proper hash type inserted in the message
136 if Msg.getparam('micalg') != None:
137 Output = Output + "Hash: MD5,SHA1,%s\r\n"%(Msg.getparam('micalg')[4:].upper())
138 Output = Output + "\r\n";
139 Output = Output + Signed.getvalue().replace("\n-","\n- -") + Signature
143 # Just return the message body
144 return (''.join(Msg.fp.readlines()),0);
148 for x in Msg.fp.readlines():
154 # Leading up to the signature
156 if Tmp == "-----BEGIN PGP SIGNED MESSAGE-----":
159 raise Error,"Unsigned text in message (at start)";
162 # In the signature plain text
164 if Tmp == "-----BEGIN PGP SIGNATURE-----":
170 if Tmp == "-----END PGP SIGNATURE-----":
176 raise Error,"Unsigned text in message (at end)";
179 # This opens GPG in 'write filter' mode. It takes Message and sends it
180 # to GPGs standard input, pipes the standard output to a temp file along
181 # with the status FD. The two tempfiles are passed to GPG by fd and are
182 # accessible from the filesystem for only a short period. Message may be
183 # None in which case GPGs stdin is closed directly after forking. This
184 # is best used for sig checking and encryption.
185 # The return result is a tuple (Exit,StatusFD,OutputFD), both fds are
186 # fully rewound and readable.
187 def GPGWriteFilter(Program,Options,Message):
188 # Make sure the tmp files we open are unreadable, there is a short race
189 # between when the temp file is opened and unlinked that some one else
190 # could open it or hard link it. This is not important however as no
191 # Secure data is fed through the temp files.
192 OldMask = os.umask(0777);
194 Output = tempfile.TemporaryFile("w+b");
195 GPGText = tempfile.TemporaryFile("w+b");
197 InPipe = [InPipe[0],InPipe[1]];
202 # Fork off GPG in a horrible way, we redirect most of its FDs
203 # Input comes from a pipe and its two outputs are spooled to unlinked
204 # temp files (ie private)
208 os.dup2(InPipe[0],0);
210 os.dup2(Output.fileno(),1);
211 os.dup2(os.open("/dev/null",os.O_WRONLY),2);
212 os.dup2(GPGText.fileno(),3);
214 Args = [Program,"--status-fd","3"] + GPGBasicOptions + GPGKeyRings + Options
215 os.execvp(Program,Args);
219 # Get rid of the other end of the pipe
226 os.write(InPipe[1],Message);
232 # Wait for GPG to finish
233 Exit = os.waitpid(Child,0);
235 # Create the result including the new readable file descriptors
236 Result = (Exit,os.fdopen(os.dup(GPGText.fileno()),"r"), \
237 os.fdopen(os.dup(Output.fileno()),"r"));
252 # This takes a text passage, a destination and a flag indicating the
253 # compatibility to use and returns an encrypted message to the recipient.
254 # It is best if the recipient is specified using the hex key fingerprint
255 # of the target, ie 0x64BE1319CCF6D393BF87FF9358A6D4EE
256 def GPGEncrypt(Message,To,PGP2):
257 Error = "KeyringError"
258 # Encrypt using the PGP5 block encoding and with the PGP5 option set.
259 # This will handle either RSA or DSA/DH asymetric keys.
260 # In PGP2 compatible mode IDEA and rfc1991 encoding are used so that
261 # PGP2 can read the result. RSA keys do not need PGP2 to be set, as GPG
262 # can read a message encrypted with blowfish and RSA.
263 searchkey = GPGKeySearch(To);
264 if len(searchkey) == 0:
265 raise Error, "No key found matching %s"%(To);
266 elif len(searchkey) > 1:
267 raise Error, "Multiple keys found matching %s"%(To);
268 if searchkey[0][4].find("E") < 0:
269 raise Error, "Key %s has no encryption capability - are all encryption subkeys expired or revoked? Are there any encryption subkeys?"%(To);
274 Res = GPGWriteFilter(GPGPath,["-r",To]+GPGEncryptOptions,Message);
277 Text = Res[2].read();
284 # We have to call gpg with a filename or it will create a packet that
285 # PGP2 cannot understand.
286 TmpName = tempfile.mktemp();
289 MsgFile = open(TmpName,"wc");
290 MsgFile.write(Message);
292 Res = GPGWriteFilter(GPGPath,["-r",To]+GPGEncryptPGP2Options+[TmpName],None);
295 Text = Res[2].read();
306 # Checks the signature of a standard PGP message, like that returned by
307 # GetClearSig. It returns a large tuple of the form:
308 # (Why,(SigId,Date,KeyFinger),(KeyID,KeyFinger,Owner,Length,PGP2),Text);
310 # Why = None if checking was OK otherwise an error string.
311 # SigID+Date represent something suitable for use in a replay cache. The
312 # date is returned as the number of seconds since the UTC epoch.
313 # The keyID is also in this tuple for easy use of the replay
315 # KeyID, KeyFinger and Owner represent the Key used to sign this message
316 # PGP2 indicates if the message was created using PGP 2.x
317 # Text is the full byte-for-byte signed text in a string
318 def GPGCheckSig(Message):
321 Res = GPGWriteFilter(GPGPath,GPGSigOptions,Message);
324 # Parse the GPG answer
335 # Grab and split up line
336 Line = Strm.readline();
339 Split = re.split("[ \n]",Line);
340 if Split[0] != "[GNUPG:]":
343 # We only process the first occurance of any tag.
344 if TagMap.has_key(Split[1]):
346 TagMap[Split[1]] = None;
348 # Good signature response
349 if Split[1] == "GOODSIG":
350 # Just in case GPG returned a bad signal before this (bug?)
354 Owner = ' '.join(Split[3:])
355 # If this message is signed with a subkey which has not yet
356 # expired, GnuPG will say GOODSIG here, even if the primary
357 # key already has expired. This came up in discussion of
358 # bug #489225. GPGKeySearch only returns non-expired keys.
359 Verify = GPGKeySearch(KeyID);
362 Why = "Key has expired (no unexpired key found in keyring matching %s)"%(KeyId);
364 # Bad signature response
365 if Split[1] == "BADSIG":
368 Why = "Verification of signature failed";
370 # Bad signature response
371 if Split[1] == "ERRSIG":
375 Why = "GPG error, ERRSIG status tag is invalid";
376 elif Split[7] == '9':
377 Why = "Unable to verify signature, signing key missing.";
378 elif Split[7] == '4':
379 Why = "Unable to verify signature, unknown packet format/key type";
381 Why = "Unable to verify signature, unknown reason";
383 if Split[1] == "NO_PUBKEY":
385 Why = "Unable to verify signature, signing key missing.";
388 if Split[1] == "EXPSIG":
390 Why = "Signature has expired";
393 if Split[1] == "EXPKEYSIG":
395 Why = "Signing key (%s, %s) has expired"%(Split[2], Split[3]);
398 if Split[1] == "KEYREVOKED" or Split[1] == "REVKEYSIG":
400 Why = "Signing key has been revoked";
403 if Split[1] == "NODATA" or Split[1] == "BADARMOR":
405 Why = "The packet was corrupted or contained no data";
408 if Split[1] == "SIG_ID":
410 Date = long(Split[4]);
412 # ValidSig has the key finger print
413 if Split[1] == "VALIDSIG":
414 # Use the fingerprint of the primary key when available
416 KeyFinger = Split[11];
418 KeyFinger = Split[2];
420 # Reopen the stream as a readable stream
421 Text = Res[2].read();
423 # A gpg failure is an automatic bad signature
424 if Exit[1] != 0 and Why == None:
426 Why = "GPG execution failed " + str(Exit[0]);
428 if GoodSig == 0 and (Why == None or len(Why) == 0):
429 Why = "Checking Failed";
431 # Try to decide if this message was sent using PGP2
433 if (re.search("-----[\n\r][\n\r]?Version: 2\\.",Message) != None):
436 return (Why,(SigId,Date,KeyFinger),(KeyID,KeyFinger,Owner,0,PGP2Message),Text);
442 # Search for keys given a search pattern. The pattern is passed directly
443 # to GPG for processing. The result is a list of tuples of the form:
444 # (KeyID,KeyFinger,Owner,Length)
445 # Which is similar to the key identification tuple output by GPGChecksig
447 # Do not return keys where the primary key has expired
448 def GPGKeySearch(SearchCriteria):
449 Args = [GPGPath] + GPGBasicOptions + GPGKeyRings + GPGSearchOptions + \
450 [SearchCriteria," 2> /dev/null"]
459 dir = os.path.expanduser("~/.gnupg")
460 if not os.path.isdir(dir):
464 Strm = os.popen(" ".join(Args),"r")
467 # Grab and split up line
468 Line = Strm.readline();
471 Split = Line.split(":")
473 # Store some of the key fields
474 if Split[0] == 'pub':
477 Length = int(Split[2])
478 Capabilities = Split[11]
479 Expired = Split[1] == 'e'
482 if Split[0] == 'fpr':
483 if Hits.has_key(Split[9]):
485 Hits[Split[9]] = None;
487 Result.append( (KeyID,Split[9],Owner,Length,Capabilities) );
493 # Print the available key information in a format similar to GPG's output
494 # We do not know the values of all the feilds so they are just replaced
496 def GPGPrintKeyInfo(Ident):
497 print "pub %u?/%s ??-??-?? %s" % (Ident[3],Ident[0][-8:],Ident[2]);
498 print " key fingerprint = 0x%s" % (Ident[1]);
500 # Perform a substition of template
501 def TemplateSubst(Map,Template):
503 Template = Template.replace(x, Map[x])
506 # The replay class uses a python DB (BSD db if avail) to implement
507 # protection against replay. Replay is an attacker capturing the
508 # plain text signed message and sending it back to the victim at some
509 # later date. Each signature has a unique signature ID (and signing
510 # Key Fingerprint) as well as a timestamp. The first stage of replay
511 # protection is to ensure that the timestamp is reasonable, in particular
512 # not to far ahead or too far behind the current system time. The next
513 # step is to look up the signature + key fingerprint in the replay database
514 # and determine if it has been recived. The database is cleaned out
515 # periodically and old signatures are discarded. By using a timestamp the
516 # database size is bounded to being within the range of the allowed times
517 # plus a little fuzz. The cache is serialized with a flocked lock file
519 def __init__(self,Database):
520 self.Lock = open(Database + ".lock","w",0600);
521 fcntl.flock(self.Lock.fileno(),fcntl.LOCK_EX);
522 self.DB = anydbm.open(Database,"c",0600);
523 self.CleanCutOff = CleanCutOff;
524 self.AgeCutOff = AgeCutOff;
525 self.FutureCutOff = FutureCutOff;
527 # Close the cache and lock
534 # Clean out any old signatures
536 CutOff = time.time() - self.CleanCutOff;
537 for x in self.DB.keys():
538 if int(self.DB[x]) <= CutOff:
541 # Check a signature. 'sig' is a 3 tuple that has the sigId, date and
544 if Sig[0] == None or Sig[1] == None or Sig[2] == None:
545 return "Invalid signature";
546 if int(Sig[1]) > time.time() + self.FutureCutOff:
547 return "Signature has a time too far in the future";
548 if self.DB.has_key(Sig[0] + '-' + Sig[2]):
549 return "Signature has already been received";
550 if int(Sig[1]) < time.time() - self.AgeCutOff:
551 return "Signature has passed the age cut off ";
552 # + str(int(Sig[1])) + ',' + str(time.time()) + "," + str(Sig);
555 # Add a signature, the sig is the same as is given to Check
557 if Sig[0] == None or Sig[1] == None:
558 raise RuntimeError,"Invalid signature";
559 if Sig[1] < time.time() - self.CleanCutOff:
561 Key = Sig[0] + '-' + Sig[2]
562 if self.DB.has_key(Key):
563 if int(self.DB[Key]) < Sig[1]:
564 self.DB[Key] = str(int(Sig[1]));
566 self.DB[Key] = str(int(Sig[1]));