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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 subcommand as SC | |
42 | import util as U | |
43 | ||
44 | for i in ['admin', 'cgi', 'remote', 'user']: | |
45 | __import__('cmd-' + i) | |
46 | ||
47 | ###-------------------------------------------------------------------------- | |
48 | ### Parsing command-line options. | |
49 | ||
50 | ## Command-line options parser. | |
51 | OPTPARSE = SC.SubcommandOptionParser( | |
52 | usage = '%prog SUBCOMMAND [ARGS ...]', | |
53 | version = '%%prog, verion %s' % VERSION, | |
54 | contexts = ['admin', 'userv', 'remote', 'cgi', 'cgi-query', 'cgi-noauth'], | |
55 | commands = SC.COMMANDS, | |
56 | description = """\ | |
57 | Manage all of those annoying passwords. | |
58 | ||
59 | This is free software, and you can redistribute it and/or modify it | |
60 | under the terms of the GNU Affero General Public License | |
61 | <http://www.gnu.org/licenses/agpl-3.0.html>. For a `.tar.gz' file | |
62 | of the source code, use the `source' command. | |
63 | """) | |
64 | ||
65 | OPTS = None | |
66 | ||
67 | ## Set up the global options. | |
68 | for short, long, props in [ | |
69 | ('-c', '--context', { | |
70 | 'metavar': 'CONTEXT', 'dest': 'context', 'default': None, | |
71 | 'help': 'run commands with the given CONTEXT' }), | |
72 | ('-f', '--config-file', { | |
73 | 'metavar': 'FILE', 'dest': 'config', | |
74 | 'default': OS.path.join(HOME, 'chpwd.conf'), | |
75 | 'help': 'read configuration from FILE.' }), | |
76 | ('-u', '--user', { | |
77 | 'metavar': 'USER', 'dest': 'user', 'default': None, | |
78 | 'help': "impersonate USER, and default context to `userv'." })]: | |
79 | OPTPARSE.add_option(short, long, **props) | |
80 | ||
81 | ###-------------------------------------------------------------------------- | |
82 | ### CGI dispatch. | |
83 | ||
84 | ## The special variables, to be picked out by `cgiparse'. | |
85 | CGI.SPECIAL['%act'] = None | |
86 | CGI.SPECIAL['%nonce'] = None | |
87 | ||
88 | ## We don't want to parse arguments until we've settled on a context; but | |
89 | ## issuing redirects in the early setup phase fails because we don't know | |
90 | ## the script name. So package the setup here. | |
91 | def cgi_setup(ctx = 'cgi-noauth'): | |
92 | global OPTS | |
93 | if OPTS: return | |
94 | OPTPARSE.context = ctx | |
95 | OPTS, args = OPTPARSE.parse_args() | |
96 | if args: raise U.ExpectedError, (500, 'Unexpected arguments to CGI') | |
97 | CONF.loadconfig(OPTS.config) | |
98 | D.opendb() | |
99 | ||
100 | def dispatch_cgi(): | |
101 | """Examine the CGI request and invoke the appropriate command.""" | |
102 | ||
103 | ## Start by picking apart the request. | |
104 | CGI.cgiparse() | |
105 | ||
106 | ## We'll be taking items off the trailing path. | |
107 | i, np = 0, len(CGI.PATH) | |
108 | ||
109 | ## Sometimes, we want to run several actions out of the same form, so the | |
110 | ## subcommand name needs to be in the query string. We use the special | |
111 | ## variable `%act' for this. If it's not set, then we use the first elment | |
112 | ## of the path. | |
113 | act = CGI.SPECIAL['%act'] | |
114 | if act is None: | |
115 | if i >= np: | |
116 | cgi_setup() | |
117 | CGI.redirect(CGI.action('login')) | |
118 | return | |
119 | act = CGI.PATH[i] | |
120 | i += 1 | |
121 | ||
122 | ## Figure out which context we're meant to be operating in, according to | |
123 | ## the requested action. Unknown actions result in an error here; known | |
124 | ## actions where we don't have enough authorization send the user back to | |
125 | ## the login page. | |
126 | for ctx in ['cgi-noauth', 'cgi-query', 'cgi']: | |
127 | try: | |
128 | c = OPTPARSE.lookup_subcommand(act, exactp = True, context = ctx) | |
129 | except U.ExpectedError, e: | |
130 | if e.code != 404: raise | |
131 | else: | |
132 | break | |
133 | else: | |
134 | raise e | |
135 | ||
136 | ## Parse the command line, and load configuration. | |
137 | cgi_setup(ctx) | |
138 | ||
139 | ## Check whether we have enough authorization. There's always enough for | |
140 | ## `cgi-noauth'. | |
141 | if ctx != 'cgi-noauth': | |
142 | ||
143 | ## If there's no token cookie, then we have to bail. | |
144 | try: token = CGI.COOKIE['chpwd-token'] | |
145 | except KeyError: | |
146 | CGI.redirect(CGI.action('login', why = 'NOAUTH')) | |
147 | return | |
148 | ||
149 | ## If we only want read-only access, then the cookie is good enough. | |
150 | ## Otherwise we must check that a nonce was supplied, and that it is | |
151 | ## correct. | |
152 | if ctx == 'cgi-query': | |
153 | nonce = None | |
154 | else: | |
155 | nonce = CGI.SPECIAL['%nonce'] | |
156 | if not nonce: | |
157 | CGI.redirect(CGI.action('login', why = 'NONONCE')) | |
158 | return | |
159 | ||
160 | ## Verify the token and nonce. | |
161 | try: | |
162 | CU.USER = HA.check_auth(token, nonce) | |
163 | except HA.AuthenticationFailed, e: | |
164 | CGI.redirect(CGI.action('login', why = e.why)) | |
165 | return | |
166 | ||
167 | ## Invoke the subcommand handler. | |
168 | c.cgi(CGI.PARAM, CGI.PATH[i:]) | |
169 | ||
170 | ###-------------------------------------------------------------------------- | |
171 | ### Main dispatch. | |
172 | ||
173 | @CTX.contextmanager | |
174 | def cli_errors(): | |
175 | """Catch expected errors and report them in the traditional Unix style.""" | |
176 | try: | |
177 | yield None | |
178 | except U.ExpectedError, e: | |
179 | SYS.stderr.write('%s: %s\n' % (OS.path.basename(SYS.argv[0]), e.msg)) | |
180 | if 400 <= e.code < 500: SYS.exit(1) | |
181 | else: SYS.exit(2) | |
182 | ||
183 | ### Main dispatch. | |
184 | ||
185 | if __name__ == '__main__': | |
186 | ||
187 | if 'REQUEST_METHOD' in ENV: | |
188 | ## This looks like a CGI request. The heavy lifting for authentication | |
189 | ## over HTTP is done in `dispatch_cgi'. | |
190 | ||
191 | with OUT.redirect_to(CGI.HTTPOutput()): | |
192 | with CGI.cgi_errors(cgi_setup): dispatch_cgi() | |
193 | ||
194 | elif 'USERV_SERVICE' in ENV: | |
195 | ## This is a Userv request. The caller's user name is helpfully in the | |
196 | ## `USERV_USER' environment variable. | |
197 | ||
198 | with cli_errors(): | |
199 | OPTS, args = OPTPARSE.parse_args() | |
200 | CONF.loadconfig(OPTS.config) | |
201 | try: CU.set_user(ENV['USERV_USER']) | |
202 | except KeyError: raise ExpectedError, (500, 'USERV_USER unset') | |
203 | with OUT.redirect_to(O.FileOutput()): | |
204 | OPTPARSE.dispatch('userv', [ENV['USERV_SERVICE']] + args) | |
205 | ||
206 | elif 'SSH_ORIGINAL_COMMAND' in ENV: | |
207 | ## This looks like an SSH request; but we present two different | |
208 | ## interfaces over SSH. We must distinguish them -- carefully: they have | |
209 | ## very different error-reporting conventions. | |
210 | ||
211 | def ssh_setup(): | |
212 | """Extract and parse the client's request from where SSH left it.""" | |
213 | global OPTS | |
214 | OPTS, args = OPTPARSE.parse_args() | |
215 | CONF.loadconfig(OPTS.config) | |
216 | cmd = SL.split(ENV['SSH_ORIGINAL_COMMAND']) | |
217 | if args: raise ExpectedError, (500, 'Unexpected arguments via SSH') | |
218 | return cmd | |
219 | ||
220 | if 'CHPWD_SSH_USER' in ENV: | |
221 | ## Setting `CHPWD_SSH_USER' to a user name is the administrator's way | |
222 | ## of telling us that this is a user request, so treat it like Userv. | |
223 | ||
224 | with cli_errors(): | |
225 | cmd = ssh_setup() | |
226 | CU.set_user(ENV['CHPWD_SSH_USER']) | |
227 | SERVICES['master'].find(USER) | |
228 | with OUT.redirect_to(O.FileOutput()): | |
229 | OPTPARSE.dispatch('userv', cmd) | |
230 | ||
231 | elif 'CHPWD_SSH_MASTER' in ENV: | |
232 | ## Setting `CHPWD_SSH_MASTER' to anything tells us that the client is | |
233 | ## making a remote-service request. We must turn on the protocol | |
234 | ## decoration machinery, but don't need to -- mustn't, indeed -- set up | |
235 | ## a user. | |
236 | ||
237 | try: | |
238 | cmd = ssh_setup() | |
239 | with OUT.redirect_to(O.RemoteOutput()): | |
240 | OPTPARSE.dispatch('remote', map(urldecode, cmd)) | |
241 | except ExpectedError, e: | |
242 | print 'ERR', e.code, e.msg | |
243 | else: | |
244 | print 'OK' | |
245 | ||
246 | else: | |
247 | ## There's probably some strange botch in the `.ssh/authorized_keys' | |
248 | ## file, but we can't do much about it from here. | |
249 | ||
250 | with cli_errors(): | |
251 | raise ExpectedError, (400, "Unabled to determine SSH context") | |
252 | ||
253 | else: | |
254 | ## Plain old command line, apparently. We default to administration | |
255 | ## commands, but allow any kind, since this is useful for debugging, and | |
256 | ## this isn't a security problem since our caller is just as privileged | |
257 | ## as we are. | |
258 | ||
259 | with cli_errors(): | |
260 | OPTS, args = OPTPARSE.parse_args() | |
261 | CONF.loadconfig(OPTS.config) | |
262 | ctx = OPTS.context | |
263 | if OPTS.user: | |
264 | CU.set_user(OPTS.user) | |
265 | if ctx is None: ctx = 'userv' | |
266 | else: | |
267 | D.opendb() | |
268 | if ctx is None: ctx = 'admin' | |
269 | with OUT.redirect_to(O.FileOutput()): | |
270 | OPTPARSE.dispatch(ctx, args) | |
271 | ||
272 | ###----- That's all, folks -------------------------------------------------- |