Accept an incoming certificate as either DER or base64 in the service plugin.

The plugin required a base64-encoded certificate and always decoded it
before processing. This doesn't work with the UI because the json module
decodes binary values already.

Try to detect if the incoming value is base64-encoded and decode if
necessary. Finally, try to pull the cert apart to validate it. This will
tell us for sure that the data is a certificate, regardless of the format
it came in as.

ticket 348

3 files changed, 78 insertions, 12 deletions

diff --git a/ipalib/errors.py b/ipalib/errors.py
index 0d1304e0..42d43ce6 100644
--- a/ipalib/errors.py
+++ b/ipalib/errors.py
@@ -1204,7 +1204,7 @@ class CertificateError(ExecutionError):
     errno = 4300
 
 
-class CertificateOperationError(ExecutionError):
+class CertificateOperationError(CertificateError):
     """
     **4301** Raised when a certificate operation cannot be completed
 
@@ -1220,6 +1220,22 @@ class CertificateOperationError(ExecutionError):
     errno = 4301
     format = _('Certificate operation cannot be completed: %(error)s')
 
+class CertificateFormatError(CertificateError):
+    """
+    **4302** Raised when a certificate is badly formatted
+
+    For example:
+
+    >>> raise CertificateFormatError(error=u'improperly formated DER-encoded certificate')
+    Traceback (most recent call last):
+      ...
+    CertificateFormatError: improperly formated DER-encoded certificate
+
+    """
+
+    errno = 4302
+    format = _('Certificate format error: %(error)s')
+
 
 class MutuallyExclusiveError(ExecutionError):
     """
diff --git a/ipalib/plugins/service.py b/ipalib/plugins/service.py
index 50e8d54f..d226f95a 100644
--- a/ipalib/plugins/service.py
+++ b/ipalib/plugins/service.py
@@ -75,6 +75,7 @@ from ipalib import Str, Flag, Bytes
 from ipalib.plugins.baseldap import *
 from ipalib import x509
 from ipalib import _, ngettext
+from ipalib import util
 from nss.error import NSPRError
 
 
@@ -130,10 +131,41 @@ def validate_certificate(ugettext, cert):
     """
     For now just verify that it is properly base64-encoded.
     """
+    if util.isvalid_base64(cert):
+        try:
+            base64.b64decode(cert)
+        except Exception, e:
+            raise errors.Base64DecodeError(reason=str(e))
+    else:
+        # We'll assume this is DER data
+        pass
+
+def normalize_certificate(cert):
+    """
+    Incoming certificates should be DER-encoded.
+
+    Note that this can't be a normalizer on the Param because only unicode
+    variables are normalized.
+    """
+    if util.isvalid_base64(cert):
+        try:
+            cert = base64.b64decode(cert)
+        except Exception, e:
+            raise errors.Base64DecodeError(reason=str(e))
+
+    # At this point we should have a certificate, either because the data
+    # was base64-encoded and now its not or it came in as DER format.
+    # Let's decode it and see. Fetching the serial number will pass the
+    # certificate through the NSS DER parser.
     try:
-        base64.b64decode(cert)
-    except Exception, e:
-        raise errors.Base64DecodeError(reason=str(e))
+        serial = unicode(x509.get_serial_number(cert, x509.DER))
+    except NSPRError, nsprerr:
+        if nsprerr.errno == -8183: # SEC_ERROR_BAD_DER
+            raise errors.CertificateFormatError(error='improperly formatted DER-encoded certificate')
+        else:
+            raise errors.CertificateFormatError(error=str(nsprerr))
+
+    return cert
 
 
 class service(LDAPObject):
@@ -196,13 +228,9 @@ class service_add(LDAPCreate):
         except errors.NotFound:
             raise errors.NotFound(reason="The host '%s' does not exist to add a service to." % hostname)
 
-        cert = entry_attrs.get('usercertificate')
+        cert = options.get('usercertificate')
         if cert:
-            cert = cert[0]
-            # FIXME: should be in a normalizer: need to fix normalizers
-            #        to work on non-unicode data
-            entry_attrs['usercertificate'] = base64.b64decode(cert)
-            # FIXME: shouldn't we request signing at this point?
+            entry_attrs['usercertificate'] = normalize_certificate(cert)
 
         if not options.get('force', False):
              # We know the host exists if we've gotten this far but we
@@ -273,6 +301,7 @@ class service_mod(LDAPUpdate):
     def pre_callback(self, ldap, dn, entry_attrs, *keys, **options):
         if 'usercertificate' in options:
             cert = options.get('usercertificate')
+            cert = normalize_certificate(cert)
             if cert:
                 (dn, entry_attrs_old) = ldap.get_entry(dn, ['usercertificate'])
                 if 'usercertificate' in entry_attrs_old:
@@ -281,8 +310,7 @@ class service_mod(LDAPUpdate):
                         x509.get_serial_number(entry_attrs_old['usercertificate'][0], x509.DER)
                     )
                     raise errors.GenericError(format=fmt)
-                # FIXME: should be in normalizer; see service_add
-                entry_attrs['usercertificate'] = base64.b64decode(cert)
+                entry_attrs['usercertificate'] = cert
             else:
                 entry_attrs['usercertificate'] = None
         return dn
diff --git a/ipalib/util.py b/ipalib/util.py
index 6bd1da54..1803e65a 100644
--- a/ipalib/util.py
+++ b/ipalib/util.py
@@ -26,6 +26,7 @@ import imp
 import logging
 import time
 import socket
+import re
 from types import NoneType
 
 from ipalib import errors
@@ -148,3 +149,24 @@ def validate_host_dns(log, fqdn):
         log.debug(
             'IPA: found %d records for %s' % (len(rs), fqdn)
         )
+
+def isvalid_base64(data):
+    """
+    Validate the incoming data as valid base64 data or not.
+
+    The character set must only include of a-z, A-Z, 0-9, + or / and
+    be padded with = to be a length divisible by 4 (so only 0-2 =s are
+    allowed). Its length must be divisible by 4. White space is
+    not significant so it is removed.
+
+    This doesn't guarantee we have a base64-encoded value, just that it
+    fits the base64 requirements.
+    """
+
+    data = ''.join(data.split())
+
+    if len(data) % 4 > 0 or \
+        re.match('^[a-zA-Z0-9\+\/]+\={0,2}$', data) is None:
+        return False
+    else:
+        return True