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):
53 # Connect to the ldap server
54 global ErrTyp, ErrMsg;
55 ErrType = EX_TEMPFAIL;
56 ErrMsg = "An error occurred while performing the LDAP lookup:";
58 l = connectLDAP(LDAPServer);
59 l.simple_bind_s("","");
61 # Search for the matching key fingerprint
62 verbmsg("Processing fingerprint %s" % FingerPrint)
63 Attrs = l.search_s(LDAPDn,ldap.SCOPE_ONELEVEL,"keyfingerprint=" + FingerPrint);
65 raise Error, "Key not found"
67 raise Error, "Oddly your key fingerprint is assigned to more than one account.."
70 for key in Attrs[0][1].keys():
71 if (key == "gidNumber"):
74 if (gidnumber_found != 1):
75 raise Error, "No gidnumber in attributes for fingerprint %s" % FingerPrint
77 # Look for the group with the gid of the user
78 GAttr = l.search_s(LDAPDn,ldap.SCOPE_ONELEVEL,"(&(objectClass=debianGroup)(gidnumber=%s))" % Attrs[0][1]["gidNumber"][0], ["gid"])
80 raise Error, "Database inconsistency found: main group for account not found in database"
82 # See if the group membership is OK
83 # Only if a group was given on the commandline
84 if GroupMember != None:
86 # Check primary group first
87 if GAttr[0][1]["gid"][0] == GroupMember:
90 # Check supplementary groups
91 for x in Attrs[0][1].get("supplementaryGid",[]):
95 raise Error, "You don't have %s group permissions."%(GroupMember);
97 # Start of main program
99 (options, arguments) = getopt.getopt(sys.argv[1:], "r:k:d:l:g:mp:v");
100 for (switch, val) in options:
102 ReplayCacheFile = val;
103 elif (switch == '-k'):
104 SetKeyrings(val.split(":"));
105 elif (switch == '-d'):
107 elif (switch == '-l'):
109 elif (switch == '-g'):
111 elif (switch == '-m'):
113 elif (switch == '-v'):
115 elif (switch == '-p'):
118 Now = time.strftime("%a, %d %b %Y %H:%M:%S",time.gmtime(time.time()));
119 ErrMsg = "Indeterminate Error";
120 ErrType = EX_TEMPFAIL;
123 # Startup the replay cache
124 ErrType = EX_TEMPFAIL;
125 if ReplayCacheFile != None:
126 ErrMsg = "Failed to initialize the replay cache:";
127 RC = ReplayCache(ReplayCacheFile);
130 ErrType = EX_PERMFAIL;
131 ErrMsg = "Failed to understand the email or find a signature:";
132 mail = email.parser.Parser().parse(sys.stdin);
133 MsgID = mail["Message-ID"]
135 print "Inspecting message %s"%MsgID;
136 verbmsg("Processing message %s" % MsgID)
137 Msg = GetClearSig(mail,1);
138 if AllowMIME == 0 and Msg[1] != 0:
139 raise Error, "PGP/MIME disallowed";
141 ErrMsg = "Message is not PGP signed:"
142 if Msg[0].find("-----BEGIN PGP SIGNED MESSAGE-----") == -1:
143 raise Error, "No PGP signature";
145 # Check the signature
146 ErrMsg = "Unable to check the signature or the signature was invalid:";
147 pgp = GPGCheckSig2(Msg[0])
150 raise UDFormatError, pgp.why
152 raise UDFormatError, "Null signature text"
154 # Check the signature against the replay cache
155 if ReplayCacheFile != None:
156 RC.process(pgp.sig_info)
160 CheckLDAP(pgp.key_fpr)
162 ErrMsg = "Verifying message:";
164 F = open(Phrases,"r");
167 if Line == "": break;
168 if pgp.text.find(Line.strip()) == -1:
169 raise Error,"Phrase '%s' was not found" % (Line.strip())
172 ErrMsg = "[%s] \"%s\" \"%s %s\"\n"%(Now,MsgID,ErrMsg,sys.exc_value);
173 sys.stderr.write(ErrMsg);
175 Trace = "==> %s: %s\n" %(sys.exc_type,sys.exc_value);
176 List = traceback.extract_tb(sys.exc_traceback);
178 Trace = Trace + "Python Stack Trace:\n";
180 Trace = Trace + " %s %s:%u: %s\n" %(x[2],x[0],x[1],x[3]);
183 sys.exit(EX_PERMFAIL);
186 print "Message %s passed"%MsgID;