Verify that the external CA certificate files are correct.

ticket 1572

install/tools/ipa-server-install

@@ -39,6 +39,7 @@ import traceback
 from ConfigParser import RawConfigParser
 import random
 import tempfile
+import nss.error
 
 from ipaserver.install import dsinstance
 from ipaserver.install import krbinstance
@@ -59,6 +60,7 @@ from ipalib import api, errors, util
 from ipalib.parameters import IA5Str
 from ipapython.config import IPAOptionParser
 from ipalib.dn import DN
+from ipalib.x509 import load_certificate_from_file, load_certificate_chain_from_file
 
 pw_name = None
 uninstalling = False
@@ -567,18 +569,51 @@ def main():
             # already having done the first stage of the CA install.
             print "CA is not installed yet. To install with an external CA is a two-stage process.\nFirst run the installer with --external-ca."
             sys.exit(1)
-        if not ipautil.file_exists(options.external_cert_file):
-            print "%s does not exist" % options.external_cert_file
-            sys.exit(1)
-        if not ipautil.file_exists(options.external_ca_file):
-            print "%s does not exist" % options.external_ca_file
-            sys.exit(1)
 
     # This will override any settings passed in on the cmdline
     if ipautil.file_exists(ANSWER_CACHE):
         dm_password = read_password("Directory Manager", confirm=False)
         options._update_loose(read_cache(dm_password))
 
+    if options.external_cert_file:
+        try:
+            extcert = load_certificate_from_file(options.external_cert_file)
+        except IOError, e:
+            print "Can't load the PKCS#10 certificate: %s." % str(e)
+            sys.exit(1)
+        except nss.error.NSPRError:
+            print "'%s' is not a valid PEM-encoded certificate." % options.external_cert_file
+            sys.exit(1)
+
+        certsubject = unicode(extcert.subject)
+        wantsubject = unicode(DN(('CN','Certificate Authority'), options.subject))
+        if certsubject.lower() != wantsubject.lower():
+            print "Subject of the PKCS#10 certificate is not correct (got %s, expected %s)." % (certsubject, wantsubject)
+            sys.exit(1)
+
+        try:
+            extchain = load_certificate_chain_from_file(options.external_ca_file)
+        except IOError, e:
+            print "Can't load the external CA chain: %s." % str(e)
+            sys.exit(1)
+        except nss.error.NSPRError:
+            print "'%s' is not a valid PEM-encoded certificate chain." % options.external_ca_file
+            sys.exit(1)
+
+        certdict = dict((unicode(cert.subject).lower(), cert) for cert in extchain)
+        certissuer = unicode(extcert.issuer)
+        if certissuer.lower() not in certdict:
+            print "The PKCS#10 certificate is not signed by the external CA (unknown issuer %s)." % certissuer
+            sys.exit(1)
+
+        cert = extcert
+        while cert.issuer != cert.subject:
+            certissuer = unicode(cert.issuer)
+            if certissuer.lower() not in certdict:
+                print "The external CA chain is incomplete (%s is missing from the chain)." % certissuer
+                sys.exit(1)
+            cert = certdict[certissuer.lower()]
+
     print "=============================================================================="
     print "This program will set up the FreeIPA Server."
     print ""

ipalib/x509.py

@@ -34,6 +34,7 @@
 import os
 import sys
 import base64
+import re
 import nss.nss as nss
 from nss.error import NSPRError
 from ipapython import ipautil
@@ -45,6 +46,8 @@ from ipalib import errors
 PEM = 0
 DER = 1
 
+PEM_REGEX = re.compile(r'(?<=-----BEGIN CERTIFICATE-----).*?(?=-----END CERTIFICATE-----)', re.DOTALL)
+
 def valid_issuer(issuer, realm):
     return issuer in ('CN=%s Certificate Authority' % realm,
                       'CN=Certificate Authority,O=%s' % realm,)
@@ -89,6 +92,21 @@ def load_certificate(data, datatype=PEM, dbdir=None):
 
     return nss.Certificate(buffer(data))
 
+def load_certificate_chain_from_file(filename, dbdir=None):
+    """
+    Load a certificate chain from a PEM file.
+
+    Returns a list of nss.Certificate objects.
+    """
+    fd = open(filename, 'r')
+    data = fd.read()
+    fd.close()
+
+    chain = PEM_REGEX.findall(data)
+    chain = [load_certificate(cert, PEM, dbdir) for cert in chain]
+
+    return chain
+
 def load_certificate_from_file(filename, dbdir=None):
     """
     Load a certificate from a PEM file.
@@ -99,7 +117,7 @@ def load_certificate_from_file(filename, dbdir=None):
     data = fd.read()
     fd.close()
 
-    return load_certificate(file, PEM, dbdir)
+    return load_certificate(data, PEM, dbdir)
 
 def get_subject(certificate, datatype=PEM, dbdir=None):
     """