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sslxmlrpc_server.py.in 12.9 KB
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#!/usr/local/bin/python
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#
# EMULAB-COPYRIGHT
# Copyright (c) 2004 University of Utah and the Flux Group.
# All rights reserved.
#
import sys
import getopt
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import os, os.path
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import traceback
import syslog
import string

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import BaseHTTPServer

from SimpleXMLRPCServer import SimpleXMLRPCDispatcher

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# Testbed specific stuff
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TBPATH = "@prefix@/lib"
if TBPATH not in sys.path:
    sys.path.append(TBPATH)
    pass

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from libdb        import *
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try:
    from M2Crypto import SSL
    from M2Crypto.SSL import SSLError
except ImportError, e:
    sys.stderr.write("error: The py-m2crypto port is not installed\n")
    sys.exit(1)
    pass
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# When debugging, runs in foreground printing to stdout instead of syslog
debug           = 0

# The port to listen on. We should get this from configure.
PORT            = 3069

# The local address. Using INADDY_ANY for now.
ADDR            = "0.0.0.0"

# The server certificate and the server CS.
server_cert     = "@prefix@/etc/server.pem"
ca_cert         = "@prefix@/etc/emulab.pem"

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#
# By default, run a wrapper class that includes all off the modules.
# The client can invoke methods of the form experiment.swapexp when
# the server is invoked in this manner.
# 
DEFAULT_MODULE = "EmulabServer"
module         = DEFAULT_MODULE
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#
# "Standard" paths for the real and development versions of the software.
#
STD_PATH       = "/usr/testbed"
STD_DEVEL_PATH = "/usr/testbed/devel"

#
# The set of paths that the user is allowed to specify in their request.  The
# path specifies where the 'emulabserver' module will be loaded from.  In
# reality, the path only has an effect on the first request in a persistent
# connection, any subsequent requests will reuse the same module.
#
ALLOWED_PATHS  = [ STD_PATH, "@prefix@" ]

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# syslog facility
LOGFACIL	= "@TBLOGFACIL@"
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##
# Taken from the SimpleXMLRPCServer module in the python installation and
# modified to support persistent connections.
#
class MyXMLRPCRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    """Simple XML-RPC request handler class.

    Handles all HTTP POST requests and attempts to decode them as
    XML-RPC requests.
    """

    ##
    # Change the default protocol so that persistent connections are the norm.
    #
    protocol_version = "HTTP/1.1"

    ##
    # Handle a POST request from the user.  This method was changed from the
    # standard version to not close the 
    #
    def do_POST(self):
        """Handles the HTTP POST request.

        Attempts to interpret all HTTP POST requests as XML-RPC calls,
        which are forwarded to the server's _dispatch method for handling.
        """

        # Update PYTHONPATH with the user's requested path.
        self.server.set_path(self.path)

        try:
            # get arguments
            data = self.rfile.read(int(self.headers["content-length"]))
            # In previous versions of SimpleXMLRPCServer, _dispatch
            # could be overridden in this class, instead of in
            # SimpleXMLRPCDispatcher. To maintain backwards compatibility,
            # check to see if a subclass implements _dispatch and dispatch
            # using that method if present.
            response = self.server._marshaled_dispatch(
                    data, getattr(self, '_dispatch', None)
                )
        except: # This should only happen if the module is buggy
            # internal error, report as HTTP server error
            self.send_response(500)
            self.end_headers()
            self.wfile.flush()
        else:
            # got a valid XML RPC response
            self.send_response(200)
            self.send_header("Content-type", "text/xml")
            self.send_header("Content-length", str(len(response)))
            self.end_headers()
            self.wfile.write(response)
            self.wfile.flush()
            pass
        return

    def log_request(self, code='-', size='-'):
        """Selectively log an accepted request."""

        if self.server.logRequests:
            BaseHTTPServer.BaseHTTPRequestHandler.log_request(self, code, size)


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#
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# A simple server based on the forking version SSLServer. We fork cause
# we want to change our uid/gid to that of the person on the other end.
# 
class MyServer(SSL.ForkingSSLServer, SimpleXMLRPCDispatcher):
    def __init__(self, debug):
        self.debug         = debug
	self.logRequests   = 0
        self.emulabserver  = None;

	ctx = SSL.Context('sslv23')
	ctx.load_cert(server_cert, server_cert)
	ctx.load_verify_info(ca_cert)
        ctx.set_verify(SSL.verify_peer | SSL.verify_fail_if_no_peer_cert, 16)
	ctx.set_allow_unknown_ca(0)
	#ctx.set_info_callback()
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        SimpleXMLRPCDispatcher.__init__(self)
        SSL.SSLServer.__init__(self, (ADDR, PORT),
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                               MyXMLRPCRequestHandler, ctx)
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	pass

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    ##
    # Log a message to stdout, if in debug mode, otherwise write to syslog.
    #
    # @param msg The message to log.
    #
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    def logit(self, msg):
        if debug:
            print msg
            pass
        else:
            syslog.syslog(syslog.LOG_INFO, msg);
            pass
        return
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    ##
    # Updates PYTHONPATH and imports the 'emulabserver' module on its first
    # invocation.  The specified path must be in the ALLOWED_PATHS list and
    # readable by the user, otherwise the request will fail.
    #
    # @param path The path from the POST request, should not include "lib" on
    # the end (e.g. "/usr/testbed")
    #
    def set_path(self, path):
        if not self.emulabserver:
            if path not in ALLOWED_PATHS:
                self.logit("Disallowed path: %s" % path)
                raise Exception("Path not allowed: %s" % path)
            path = os.path.join(path, "lib")
            if not os.access(path, os.X_OK):
                self.logit("Path not accessible by user: %s" % path)
                raise Exception("Permission denied: %s" % path)

            if path not in sys.path:
                sys.path.append(path)
                pass
            from emulabserver import EmulabServer
            
            self.emulabserver = EmulabServer(readonly=0)
            pass
        return
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    #
    # There might be a better arrangement, but the problem is that we
    # do not want to create the server instance until we get a chance
    # to look at the certificate and determine the priv level. See
    # below in process_request(). 
    #
    def _dispatch(self, method, params):
        try:
            meth = getattr(self.emulabserver, method);
        except AttributeError:
            raise Exception('method "%s" is not supported' % method)
        else:
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            self.logit("Calling method '" + method + "'");
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            return apply(meth, params);
        pass

    #
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    # Get the unix_uid for the user. User must be active. 
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    #
    def getuserid(self, uid):
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        userQuery = DBQueryFatal("select unix_uid,status from users "
                                 "where uid=%s",
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                                 (uid,))
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        if len(userQuery) == 0:
            return 0
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        if (userQuery[0][1] != "active"):
            return -1
        
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        return int(userQuery[0][0])
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    #
    # Check if the user is an admin.
    #
    def isadminuser(self, uid):
        res = DBQueryFatal("select admin from users where uid=%s", (uid,))

        if len(res) == 0:
            return 0

        return res[0][0]
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    #
    # Check the certificate serial number. 
    #
    def checkcert(self, uid, serial):
        res = DBQueryFatal("select idx from user_sslcerts "
                           "where uid=%s and idx=%s",
                           (uid, serial))

        return len(res)
    
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    #
    # Get the group list for the user.
    #
    def getusergroups(self, user):
        result = []
        
        res = DBQueryFatal("select distinct g.gid,g.unix_gid "
                           "  from group_membership as m "
                           "left join groups as g on "
                           "  g.pid=m.pid and g.gid=m.gid "
                           "where m.uid=%s "
                           "order by date_approved asc ",
                           (user,))
        
        for group in res:
            result.append(int(group[1]));
            pass
    
        return result
    
    #
    # Flip to the user that is in the certificate.
    #
    def fliptouser(self, request, client):
        subject = request.get_peer_cert().get_subject()
        if self.debug:
            self.logit(str(subject))
            pass
        
        self.user = getattr(subject, "CN");
        #
        # Must be a valid and non-zero unix_uid from the DB.
        #
        self.uid = self.getuserid(self.user)
        
        if self.uid == 0:
            self.logit('No such user: "%s"' % self.user)
            raise Exception('No such user: "%s"' % self.user)
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        if self.uid == -1:
            self.logit('User "%s" is not active' % self.user)
            raise Exception('User "%s" is not active' % self.user)
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        self.admin = self.isadminuser(self.user)
        if not self.admin:
            ALLOWED_PATHS.extend(map(lambda x: os.path.join(STD_DEVEL_PATH, x),
                                     os.listdir(STD_DEVEL_PATH)))
            pass
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        self.glist = self.getusergroups(self.user);
        if len(self.glist) == 0:
            self.logit('No groups for user: "%s"' % self.user)
            raise Exception('No groups for user: "%s"' % self.user)

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        self.logit("Connect from %s: %s %s" %
                   (client[0], self.user, str(self.glist)))
        
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        #
        # Check the certificate serial number. At the moment, the serial
        # must match a certificate that is in the DB for that user. This
        # is my crude method of certificate revocation. 
        #
        serial = request.get_peer_cert().get_serial_number()
        
        if self.checkcert(self.user, serial) == 0:
            self.logit('No such cert with serial "%s"' % serial)
            raise Exception('No such cert with serial "%s"' % serial)
        
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        try:
            os.setgid(self.glist[0])
            os.setgroups(self.glist)
            os.setuid(self.uid)

            os.environ["USER"]    = self.user;
            os.environ["LOGNAME"] = self.user;
            pass
        except:
            traceback.print_exc()
            os._exit(1)
            pass
        pass

    #
    # XXX - The builtin process_request() method for ForkingMixIn is
    # broken; it closes the "request" in the parent which shuts down
    # the ssl connection. So, I have moved the close_request into the
    # child where it should be, and in the parent I close the socket
    # by reaching into the Connection() class.
    # 
    # In any event, I need to do some other stuff in the child before we
    # actually handle the request. 
    # 
    def process_request(self, request, client_address):
        """Fork a new subprocess to process the request."""
        self.collect_children()
        pid = os.fork()
        if pid:
            # Parent process
            if self.active_children is None:
                self.active_children = []
            self.active_children.append(pid)
            request.socket.close()
            return
        else:
            # Child process.
            # This must never return, hence os._exit()!
            try:
                self.fliptouser(request, client_address);
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                # Remove the old path since the user can request a different
                # one.
                sys.path.remove(TBPATH)
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                self.finish_request(request, client_address)
                self.close_request(request)
                self.logit("request finished");
                os._exit(0)
            except:
                try:
                    self.handle_error(request, client_address)
                finally:
                    os._exit(1)

    def verify_request(self, request, client_address):
        return True

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    pass

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#
# Check for debug flag.
# 
if len(sys.argv) > 1 and sys.argv[1] == "-d":
    debug = 1
    pass

#
# Daemonize when not running in debug mode.
#
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if not debug:
    #
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    # Connect to syslog.
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    #
    syslog.openlog("sslxmlrpc", syslog.LOG_PID,
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                   getattr(syslog, "LOG_" + string.upper(LOGFACIL)))
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    syslog.syslog(syslog.LOG_INFO, "SSL XMLRPC server starting up");

    #
    # Daemonize. We redirect our output into a log file cause I have no
    # idea what is going to use plain print. 
    #
    try:
        fp = open("@prefix@/log/sslxmlrpc_server.log", "a");
        sys.stdout = fp
        sys.stderr = fp
        sys.stdin.close();
        pass
    except:
        print "Could not open log file for append"
        sys.exit(1);
        pass

    pid = os.fork()
    if pid:
        os.system("echo " + str(pid) + " > /var/run/sslxmlrpc_server.pid")
        sys.exit(0)
        pass
    os.setsid();
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    pass

#
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# Create the server and serve forever. We register the instance above
# when we process the request cause we want to look at the cert before
# we decide on the priv level. 
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# 
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server = MyServer(debug);
server.serve_forever()