mdw@git.distorted.org.uk Git - chopwood/blob - chpwd

   1 #! /usr/bin/python
   2 ###
   3 ### Password management
   4 ###
   5 ### (c) 2012 Mark Wooding
   6 ###
   7
   8 ###----- Licensing notice ---------------------------------------------------
   9 ###
  10 ### This file is part of Chopwood: a password-changing service.
  11 ###
  12 ### Chopwood is free software; you can redistribute it and/or modify
  13 ### it under the terms of the GNU Affero General Public License as
  14 ### published by the Free Software Foundation; either version 3 of the
  15 ### License, or (at your option) any later version.
  16 ###
  17 ### Chopwood is distributed in the hope that it will be useful,
  18 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ### GNU Affero General Public License for more details.
  21 ###
  22 ### You should have received a copy of the GNU Affero General Public
  23 ### License along with Chopwood; if not, see
  24 ### <http://www.gnu.org/licenses/>.
  25
  26 from __future__ import with_statement
  27
  28 import contextlib as CTX
  29 import optparse as OP
  30 import os as OS; ENV = OS.environ
  31 import shlex as SL
  32 import sys as SYS
  33
  34 from auto import HOME, VERSION
  35 import cgi as CGI
  36 import cmdutil as CU
  37 import config as CONF; CFG = CONF.CFG
  38 import dbmaint as D
  39 import httpauth as HA
  40 import output as O; OUT = O.OUT
  41 import service as S
  42 import subcommand as SC
  43 import util as U
  44
  45 for i in ['admin', 'cgi', 'remote', 'user']:
  46   __import__('cmd-' + i)
  47
  48 ###--------------------------------------------------------------------------
  49 ### Parsing command-line options.
  50
  51 ## Command-line options parser.
  52 OPTPARSE = SC.SubcommandOptionParser(
  53   usage = '%prog SUBCOMMAND [ARGS ...]',
  54   version = '%%prog, verion %s' % VERSION,
  55   contexts = ['admin', 'userv', 'remote', 'cgi', 'cgi-query', 'cgi-noauth'],
  56   commands = SC.COMMANDS,
  57   description = """\
  58 Manage all of those annoying passwords.
  59
  60 This is free software, and you can redistribute it and/or modify it
  61 under the terms of the GNU Affero General Public License
  62 <http://www.gnu.org/licenses/agpl-3.0.html>.  For a `.tar.gz' file
  63 of the source code, use the `source' command.
  64 """)
  65
  66 OPTS = None
  67
  68 ## Set up the global options.
  69 for short, long, props in [
  70   ('-c', '--context', {
  71     'metavar': 'CONTEXT', 'dest': 'context', 'default': None,
  72     'help': 'run commands with the given CONTEXT' }),
  73   ('-f', '--config-file', {
  74     'metavar': 'FILE', 'dest': 'config',
  75     'default': ENV.get('CHPWD_CONFIG',
  76                        OS.path.join(HOME, 'chpwd.conf')),
  77     'help': 'read configuration from FILE.' }),
  78   ('-s', '--ssl', {
  79     'dest': 'sslp', 'action': 'store_true',
  80     'help': 'pretend CGI connection is carried over SSL/TLS' }),
  81   ('-u', '--user', {
  82     'metavar': 'USER', 'dest': 'user', 'default': None,
  83     'help': "impersonate USER, and default context to `userv'." })]:
  84   OPTPARSE.add_option(short, long, **props)
  85
  86 ###--------------------------------------------------------------------------
  87 ### CGI dispatch.
  88
  89 ## The special variables, to be picked out by `cgiparse'.
  90 CGI.SPECIAL['%act'] = None
  91 CGI.SPECIAL['%nonce'] = None
  92 CGI.SPECIAL['%user'] = None
  93
  94 ## We don't want to parse arguments until we've settled on a context; but
  95 ## issuing redirects in the early setup phase fails because we don't know
  96 ## the script name.  So package the setup here.
  97 def cgi_setup(ctx = 'cgi-noauth'):
  98   global OPTS
  99   if OPTS: return
 100   OPTPARSE.context = ctx
 101   OPTS, args = OPTPARSE.parse_args()
 102   if args: raise U.ExpectedError, (500, 'Unexpected arguments to CGI')
 103   CONF.loadconfig(OPTS.config)
 104   D.opendb()
 105
 106 def dispatch_cgi():
 107   """Examine the CGI request and invoke the appropriate command."""
 108
 109   ## Start by picking apart the request.
 110   CGI.cgiparse()
 111
 112   ## We'll be taking items off the trailing path.
 113   i, np = 0, len(CGI.PATH)
 114
 115   ## Sometimes, we want to run several actions out of the same form, so the
 116   ## subcommand name needs to be in the query string.  We use the special
 117   ## variable `%act' for this.  If it's not set, then we use the first elment
 118   ## of the path.
 119   act = CGI.SPECIAL['%act']
 120   if act is None:
 121     if i >= np:
 122       cgi_setup()
 123       CGI.redirect(CGI.action('login'))
 124       return
 125     act = CGI.PATH[i]
 126     i += 1
 127
 128   ## Figure out which context we're meant to be operating in, according to
 129   ## the requested action.  Unknown actions result in an error here; known
 130   ## actions where we don't have enough authorization send the user back to
 131   ## the login page.
 132   for ctx in ['cgi-noauth', 'cgi-query', 'cgi']:
 133     try:
 134       c = OPTPARSE.lookup_subcommand(act, exactp = True, context = ctx)
 135     except U.ExpectedError, e:
 136       if e.code != 404: raise
 137     else:
 138       break
 139   else:
 140     raise e
 141
 142   ## Parse the command line, and load configuration.
 143   cgi_setup(ctx)
 144
 145   ## Check whether we have enough authorization.  There's always enough for
 146   ## `cgi-noauth'.
 147   if ctx != 'cgi-noauth':
 148
 149     ## The next part of the URL should be the user name, so that caches don't
 150     ## cross things over.
 151     expuser = CGI.SPECIAL['%user']
 152     if expuser is None:
 153       if i >= np: raise U.ExpectedError, (404, 'Missing user name')
 154       expuser = CGI.PATH[i]
 155       i += 1
 156
 157     ## If there's no token cookie, then we have to bail.
 158     try: token = CGI.COOKIE['chpwd-token']
 159     except KeyError:
 160       CGI.redirect(CGI.action('login', why = 'NOAUTH'))
 161       return
 162
 163     ## If we only want read-only access, then the cookie is good enough.
 164     ## Otherwise we must check that a nonce was supplied, and that it is
 165     ## correct.
 166     if ctx == 'cgi-query':
 167       nonce = None
 168     else:
 169       nonce = CGI.SPECIAL['%nonce']
 170       if not nonce:
 171         CGI.redirect(CGI.action('login', why = 'NONONCE'))
 172         return
 173
 174     ## Verify the token and nonce.
 175     try:
 176       CU.USER = HA.check_auth(token, nonce)
 177     except HA.AuthenticationFailed, e:
 178       CGI.redirect(CGI.action('login', why = e.why))
 179       return
 180     if CU.USER != expuser: raise U.ExpectedError, (401, 'User mismatch')
 181     CGI.STATE.kw['user'] = CU.USER
 182
 183   ## Invoke the subcommand handler.
 184   c.cgi(CGI.PARAM, CGI.PATH[i:])
 185
 186 ###--------------------------------------------------------------------------
 187 ### Main dispatch.
 188
 189 @CTX.contextmanager
 190 def cli_errors():
 191   """Catch expected errors and report them in the traditional Unix style."""
 192   try:
 193     yield None
 194   except U.ExpectedError, e:
 195     SYS.stderr.write('%s: %s\n' % (OS.path.basename(SYS.argv[0]), e.msg))
 196     if 400 <= e.code < 500: SYS.exit(1)
 197     else: SYS.exit(2)
 198
 199 ### Main dispatch.
 200
 201 if __name__ == '__main__':
 202
 203   if 'REQUEST_METHOD' in ENV:
 204     ## This looks like a CGI request.  The heavy lifting for authentication
 205     ## over HTTP is done in `dispatch_cgi'.
 206
 207     with OUT.redirect_to(CGI.HTTPOutput()):
 208       with CGI.cgi_errors(cgi_setup): dispatch_cgi()
 209
 210   elif 'USERV_SERVICE' in ENV:
 211     ## This is a Userv request.  The caller's user name is helpfully in the
 212     ## `USERV_USER' environment variable.
 213
 214     with cli_errors():
 215       OPTS, args = OPTPARSE.parse_args()
 216       CONF.loadconfig(OPTS.config)
 217       try: CU.set_user(ENV['USERV_USER'])
 218       except KeyError: raise ExpectedError, (500, 'USERV_USER unset')
 219       with OUT.redirect_to(O.FileOutput()):
 220         OPTPARSE.dispatch('userv', [ENV['USERV_SERVICE']] + args)
 221
 222   elif 'SSH_ORIGINAL_COMMAND' in ENV:
 223     ## This looks like an SSH request; but we present two different
 224     ## interfaces over SSH.  We must distinguish them -- carefully: they have
 225     ## very different error-reporting conventions.
 226
 227     def ssh_setup():
 228       """Extract and parse the client's request from where SSH left it."""
 229       global OPTS
 230       OPTS, args = OPTPARSE.parse_args()
 231       CONF.loadconfig(OPTS.config)
 232       cmd = SL.split(ENV['SSH_ORIGINAL_COMMAND'])
 233       if args: raise U.ExpectedError, (500, 'Unexpected arguments via SSH')
 234       return cmd
 235
 236     if 'CHPWD_SSH_USER' in ENV:
 237       ## Setting `CHPWD_SSH_USER' to a user name is the administrator's way
 238       ## of telling us that this is a user request, so treat it like Userv.
 239
 240       with cli_errors():
 241         cmd = ssh_setup()
 242         CU.set_user(ENV['CHPWD_SSH_USER'])
 243         S.SERVICES['master'].find(CU.USER)
 244         with OUT.redirect_to(O.FileOutput()):
 245           OPTPARSE.dispatch('userv', cmd)
 246
 247     elif 'CHPWD_SSH_MASTER' in ENV:
 248       ## Setting `CHPWD_SSH_MASTER' to anything tells us that the client is
 249       ## making a remote-service request.  We must turn on the protocol
 250       ## decoration machinery, but don't need to -- mustn't, indeed -- set up
 251       ## a user.
 252
 253       try:
 254         cmd = ssh_setup()
 255         with OUT.redirect_to(O.RemoteOutput()):
 256           OPTPARSE.dispatch('remote', map(CGI.urldecode, cmd))
 257       except U.ExpectedError, e:
 258         print 'ERR', e.code, e.msg
 259       else:
 260         print 'OK'
 261
 262     else:
 263       ## There's probably some strange botch in the `.ssh/authorized_keys'
 264       ## file, but we can't do much about it from here.
 265
 266       with cli_errors():
 267         raise U.ExpectedError, (400, "Unabled to determine SSH context")
 268
 269   else:
 270     ## Plain old command line, apparently.  We default to administration
 271     ## commands, but allow any kind, since this is useful for debugging, and
 272     ## this isn't a security problem since our caller is just as privileged
 273     ## as we are.
 274
 275     with cli_errors():
 276       OPTS, args = OPTPARSE.parse_args()
 277       CONF.loadconfig(OPTS.config)
 278       CGI.SSLP = OPTS.sslp
 279       ctx = OPTS.context
 280       if OPTS.user:
 281         CU.set_user(OPTS.user)
 282         if ctx is None: ctx = 'userv'
 283       else:
 284         D.opendb()
 285         if ctx is None: ctx = 'admin'
 286       with OUT.redirect_to(O.FileOutput()):
 287         OPTPARSE.dispatch(ctx, args)
 288
 289 ###----- That's all, folks --------------------------------------------------