Allow server-side validation of client ssl certs

This adds a 'ca_file' config option that points to a local
CA cert that will be used to verify certs provided by
connecting clients. The 'ca_file' option is only used if the
server is already properly configured to to use SSL - that
means having a valid 'cert_file' and 'key_file'. If no 'ca_file'
is provided, the behavior will remain the same - the server
will still provide its cert to clients, but it will ignore
certs sent back from those clients.

Fixes bug 1032451

Change-Id: Ie48646b0fc5398ba7cda2fb627b820f533482e00

doc/source/configuring.rst

@@ -187,6 +187,14 @@ SSL-wrapped socket.
 
 Optional. Default: not enabled.
 
+* ``ca_file=PATH``
+
+Path to the CA certificate file the server should use to validate client
+certificates provided during an SSL handshake. This is ignored if
+``cert_file`` and ''key_file`` are not set.
+
+Optional. Default: not enabled.
+
 * ``registry_client_protocol=PROTOCOL``
 
 If you run a secure Registry server, you need to set this value to ``https``

etc/glance-api.conf

@@ -81,6 +81,9 @@ use_syslog = False
 # Private key file to use when starting API server securely
 # key_file = /path/to/keyfile
 
+# CA certificate file to use to verify connecting clients
+# ca_file = /path/to/cafile
+
 # ================= Security Options ==========================
 
 # AES key for encrypting store 'location' metadata, including

etc/glance-registry.conf

@@ -63,3 +63,6 @@ use_syslog = False
 
 # Private key file to use when starting registry server securely
 # key_file = /path/to/keyfile
+
+# CA certificate file to use to verify connecting clients
+# ca_file = /path/to/cafile

glance/common/wsgi.py

@@ -53,6 +53,7 @@ bind_opts = [
 socket_opts = [
     cfg.IntOpt('backlog', default=4096),
     cfg.IntOpt('tcp_keepidle', default=600),
+    cfg.StrOpt('ca_file'),
     cfg.StrOpt('cert_file'),
     cfg.StrOpt('key_file'),
 ]
@@ -109,15 +110,30 @@ def get_socket(default_port):
                              "specify both a cert_file and key_file "
                              "option value in your configuration file"))
 
+    def wrap_ssl(sock):
+        ssl_kwargs = {
+            'server_side': True,
+            'certfile': cert_file,
+            'keyfile': key_file,
+            'cert_reqs': ssl.CERT_NONE,
+        }
+
+        if CONF.ca_file:
+            ssl_kwargs['ca_certs'] = CONF.ca_file
+            ssl_kwargs['cert_reqs'] = ssl.CERT_REQUIRED
+
+        return ssl.wrap_socket(sock, **ssl_kwargs)
+
     sock = None
     retry_until = time.time() + 30
     while not sock and time.time() < retry_until:
         try:
-            sock = eventlet.listen(bind_addr, backlog=CONF.backlog,
+            sock = eventlet.listen(bind_addr,
+                                   backlog=CONF.backlog,
                                    family=address_family)
             if use_ssl:
-                sock = ssl.wrap_socket(sock, certfile=cert_file,
-                                       keyfile=key_file)
+                sock = wrap_ssl(sock)
+
         except socket.error, err:
             if err.args[0] != errno.EADDRINUSE:
                 raise