4 # Check PGP signed emails
6 # This script verifies the signature on incoming mail for a couple of things
7 # - That the signature is valid, recent and is not replay
8 # - The signer is in the LDAP directory and is in the right group
9 # - The message contains no extra text that is not signed.
12 # -r Replay cache file, if unset replay checking is disabled
13 # -k Colon seperated list of keyrings to use
14 # -d LDAP search base DN
16 # -g supplementary group membership
17 # -p File of Phrases that must be in the plaintext.
18 # -m Disallow PGP/MIME
21 # Typical Debian invokation may look like:
22 # sigcheck -k /usr/share/keyrings/debian-keyring.gpg:/usr/share/keyrings/debian-keyring.pgp \
23 # -d ou=users,dc=debian,dc=org -l db.debian.org \
24 # -m debian.org -a admin@db.debian.org \
25 # -e /etc/userdir-ldap/templtes/error-reply -- test.sh
27 import sys, traceback, time, os;
29 import email, email.parser
30 from userdir_gpg import *;
33 EX_PERMFAIL = 65; # EX_DATAERR
34 Error = 'Message Error';
37 ReplayCacheFile = None;
47 sys.stderr.write(msg + "\n")
49 # Match the key fingerprint against an LDAP directory
50 def CheckLDAP(FingerPrint):
54 # Connect to the ldap server
55 global ErrTyp, ErrMsg;
56 ErrType = EX_TEMPFAIL;
57 ErrMsg = "An error occurred while performing the LDAP lookup:";
59 l = userdir_ldap.connectLDAP(LDAPServer);
60 l.simple_bind_s("","");
62 # Search for the matching key fingerprint
63 verbmsg("Processing fingerprint %s" % FingerPrint)
64 Attrs = l.search_s(LDAPDn,ldap.SCOPE_ONELEVEL,"keyfingerprint=" + FingerPrint);
66 raise Error, "Key not found"
68 raise Error, "Oddly your key fingerprint is assigned to more than one account.."
71 for key in Attrs[0][1].keys():
72 if (key == "gidNumber"):
75 if (gidnumber_found != 1):
76 raise Error, "No gidnumber in attributes for fingerprint %s" % FingerPrint
78 # Look for the group with the gid of the user
79 GAttr = l.search_s(LDAPDn,ldap.SCOPE_ONELEVEL,"(&(objectClass=debianGroup)(gidnumber=%s))" % Attrs[0][1]["gidNumber"][0], ["gid"])
81 raise Error, "Database inconsistency found: main group for account not found in database"
83 # See if the group membership is OK
84 # Only if a group was given on the commandline
85 if GroupMember != None:
87 # Check primary group first
88 if GAttr[0][1]["gid"][0] == GroupMember:
91 # Check supplementary groups
92 for x in Attrs[0][1].get("supplementaryGid",[]):
96 raise Error, "You don't have %s group permissions."%(GroupMember);
98 # Start of main program
100 (options, arguments) = getopt.getopt(sys.argv[1:], "r:k:d:l:g:mp:v");
101 for (switch, val) in options:
103 ReplayCacheFile = val;
104 elif (switch == '-k'):
105 SetKeyrings(val.split(":"));
106 elif (switch == '-d'):
108 elif (switch == '-l'):
110 elif (switch == '-g'):
112 elif (switch == '-m'):
114 elif (switch == '-v'):
116 elif (switch == '-p'):
119 Now = time.strftime("%a, %d %b %Y %H:%M:%S",time.gmtime(time.time()));
120 ErrMsg = "Indeterminate Error";
121 ErrType = EX_TEMPFAIL;
124 # Startup the replay cache
125 ErrType = EX_TEMPFAIL;
126 if ReplayCacheFile != None:
127 ErrMsg = "Failed to initialize the replay cache:";
128 RC = ReplayCache(ReplayCacheFile);
131 ErrType = EX_PERMFAIL;
132 ErrMsg = "Failed to understand the email or find a signature:";
133 mail = email.parser.Parser().parse(sys.stdin);
134 MsgID = mail["Message-ID"]
136 print "Inspecting message %s"%MsgID;
137 verbmsg("Processing message %s" % MsgID)
138 Msg = GetClearSig(mail,1);
139 if AllowMIME == 0 and Msg[1] != 0:
140 raise Error, "PGP/MIME disallowed";
142 ErrMsg = "Message is not PGP signed:"
143 if Msg[0].find("-----BEGIN PGP SIGNED MESSAGE-----") == -1:
144 raise Error, "No PGP signature";
146 # Check the signature
147 ErrMsg = "Unable to check the signature or the signature was invalid:";
148 pgp = GPGCheckSig2(Msg[0])
151 raise UDFormatError, pgp.why
153 raise UDFormatError, "Null signature text"
155 # Check the signature against the replay cache
156 if ReplayCacheFile != None:
157 RC.process(pgp.sig_info)
161 CheckLDAP(pgp.key_fpr)
163 ErrMsg = "Verifying message:";
165 F = open(Phrases,"r");
168 if Line == "": break;
169 if pgp.text.find(Line.strip()) == -1:
170 raise Error,"Phrase '%s' was not found" % (Line.strip())
173 ErrMsg = "[%s] \"%s\" \"%s %s\"\n"%(Now,MsgID,ErrMsg,sys.exc_value);
174 sys.stderr.write(ErrMsg);
176 Trace = "==> %s: %s\n" %(sys.exc_type,sys.exc_value);
177 List = traceback.extract_tb(sys.exc_traceback);
179 Trace = Trace + "Python Stack Trace:\n";
181 Trace = Trace + " %s %s:%u: %s\n" %(x[2],x[0],x[1],x[3]);
184 sys.exit(EX_PERMFAIL);
187 print "Message %s passed"%MsgID;