1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
|
/* common.c --- Common routines, constants, etc. Used by all the wrappers.
*
* Copyright (C) 1998-2018 by the Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
#include "common.h"
/* Passed in by configure. */
#define SCRIPTDIR PREFIX "/scripts/" /* trailing slash */
#define MODULEDIR PREFIX /* no trailing slash */
const char* scriptdir = SCRIPTDIR;
const char* moduledir = MODULEDIR;
char* python = PYTHON;
/* Global variable used as a flag */
int running_as_cgi = 0;
/* Some older systems don't define strerror(). Provide a replacement that is
* good enough for our purposes.
*/
#ifndef HAVE_STRERROR
extern char *sys_errlist[];
extern int sys_nerr;
char* strerror(int errno)
{
if (errno < 0 || errno >= sys_nerr) {
return "unknown error";
}
else {
return sys_errlist[errno];
}
}
#endif /* ! HAVE_STRERROR */
/* Report on errors and exit
*/
#define BUFSIZE 1024
void
fatal(const char* ident, int exitcode, char* format, ...)
{
#ifndef HAVE_VSNPRINTF
/* A replacement is provided in vsnprintf.c for ancient systems still
* lacking one in their C library.
*/
int vsnprintf(char*, size_t, const char*, va_list);
#endif /* !HAVE_VSNPRINTF */
char log_entry[BUFSIZE];
va_list arg_ptr;
va_start(arg_ptr, format);
vsnprintf(log_entry, BUFSIZE, format, arg_ptr);
va_end(arg_ptr);
#ifdef HAVE_SYSLOG
/* Write to the console, maillog is often mostly ignored, and root
* should definitely know about any problems.
*/
openlog(ident, LOG_CONS, LOG_MAIL);
syslog(LOG_ERR, "%s\n", log_entry);
closelog();
#endif /* HAVE_SYSLOG */
#ifdef HELPFUL
/* If we're running as a CGI script, we also want to write the log
* file out as HTML, so the admin who is probably trying to debug his
* installation will have a better clue as to what's going on.
*
* Otherwise, print to stderr a short message, hopefully returned to
* the sender by the MTA.
*/
if (running_as_cgi) {
printf("Content-type: text/html\n\n");
printf("<head>\n");
printf("<title>Mailman CGI error!!!</title>\n");
printf("</head><body>\n");
printf("<h1>Mailman CGI error!!!</h1>\n");
printf("The Mailman CGI wrapper encountered a fatal error. ");
printf("This entry is being stored in your syslog:");
printf("\n<pre>\n");
printf("%s", log_entry);
printf("</pre>\n");
}
else
fprintf(stderr, "%s\n", log_entry);
#endif /* HELPFUL */
exit(exitcode);
}
/* Is the parent process allowed to call us?
*/
void
check_caller(const char* ident, const char* parentgroup)
{
GID_T mygid = getgid();
struct group *mygroup = getgrgid(mygid);
char* option;
char* server;
char* wrapper;
if (running_as_cgi) {
option = "--with-cgi-gid";
server = "web";
wrapper = "CGI";
}
else {
option = "--with-mail-gid";
server = "mail";
wrapper = "mail";
}
if (!mygroup)
fatal(ident, GROUP_NAME_NOT_FOUND,
"Failure to find group name for GID %d. Mailman\n"
"expected the %s wrapper to be executed as group\n"
"\"%s\", but the system's %s server executed the\n"
"wrapper as GID %d for which the name could not be\n"
"found. Try adding GID %d to your system as \"%s\",\n"
"or tweak your %s server to run the wrapper as group\n"
"\"%s\".",
mygid, wrapper, parentgroup, server, mygid, mygid,
parentgroup, server, parentgroup);
if (strcmp(parentgroup, mygroup->gr_name))
fatal(ident, GROUP_MISMATCH,
"Group mismatch error. Mailman expected the %s\n"
"wrapper script to be executed as group \"%s\", but\n"
"the system's %s server executed the %s script as\n"
"group \"%s\". Try tweaking the %s server to run the\n"
"script as group \"%s\", or re-run configure, \n"
"providing the command line option `%s=%s'.",
wrapper, parentgroup, server, wrapper, mygroup->gr_name,
server, parentgroup, option, mygroup->gr_name);
}
/* list of environment variables which are kept in the given
* environment. Some may or may not be hand crafted and passed into
* the execv'd environment.
*
* TBD: The logic of this should be inverted. IOW, we should audit the
* Mailman CGI code for those environment variables that are used, and
* specifically white list them, removing all other variables.
* MAS: This is now done.
*
* John Viega
* also suggests imposing a maximum size just in case Python doesn't handle
* them right (which it should because Python strings have no hard limits).
*/
static char* keepenvars[] = {
"CONTENT_TYPE=",
"HOST=",
"HTTP_COOKIE=",
"HTTP_FORWARDED_FOR=",
"HTTP_HOST=",
"HTTP_X_FORWARDED_FOR=",
"LOGNAME=",
"PATH_INFO=",
"QUERY_STRING=",
"REMOTE_ADDR=",
"REQUEST_METHOD=",
"REQUEST_URI=",
"SCRIPT_NAME=",
"SERVER_NAME=",
"SERVER_PORT=",
"USER=",
"CONTENT_LENGTH=",
"DOCUMENT_ROOT=",
"SERVER_PROTOCOL=",
"REQUEST_SCHEME=",
"HTTPS=",
"REMOTE_PORT=",
NULL
};
/* Run a Python script out of the script directory
*
* args[0] should be the abs path to the Python script to execute
* argv[1:] are other args for the script
* env may or may not contain PYTHONPATH, we'll substitute our own
*
* TBD: third argument env may not be universally portable
*/
int
run_script(const char* script, int argc, char** argv, char** env)
{
const char envstr[] = "PYTHONPATH=";
const int envlen = strlen(envstr);
int envcnt = 0;
int i, j, status;
char** newenv;
char** newargv;
/* We need to set the real gid to the effective gid because there are
* some Linux systems which do not preserve the effective gid across
* popen() calls. This breaks mail delivery unless the ~mailman/data
* directory is chown'd to the uid that runs mail programs, and that
* isn't a viable alternative.
*/
#ifdef HAVE_SETREGID
status = setregid(getegid(), -1);
if (status)
fatal(logident, SETREGID_FAILURE, "%s", strerror(errno));
#endif /* HAVE_SETREGID */
/* We want to tightly control how the CGI scripts get executed.
* For portability and security, the path to the Python executable
* is hard-coded into this C wrapper, rather than encoded in the #!
* line of the script that gets executed. So we invoke those
* scripts by passing the script name on the command line to the
* Python executable.
*
* We also need to hack on the PYTHONPATH environment variable so
* that the path to the installed Mailman modules will show up
* first on sys.path.
*
*/
for (envcnt = 0; env[envcnt]; envcnt++)
;
/* okay to be a little too big */
newenv = (char**)malloc(sizeof(char*) * (envcnt + 2));
/* filter out any troublesome environment variables */
for (i = 0, j = 0; i < envcnt; i++) {
char** k = &keepenvars[0];
int keep = 0;
while (*k) {
if (!strncmp(*k, env[i], strlen(*k))) {
keep = 1;
break;
}
*k++;
}
if (keep)
newenv[j++] = env[i];
}
/* Tack on our own version of PYTHONPATH, which should contain only
* the path to the Mailman package modules.
*
* $(PREFIX)/modules
*/
newenv[j] = (char*)malloc(sizeof(char) * (
strlen(envstr) +
strlen(moduledir) +
1));
strcpy(newenv[j], envstr);
strcat(newenv[j], moduledir);
j++;
newenv[j] = NULL;
/* Now put together argv. This will contain first the absolute path
* to the Python executable, then the -S option (to speed executable
* start times), then the absolute path to the script, then any
* additional args passed in argv above.
*/
newargv = (char**)malloc(sizeof(char*) * (argc + 3));
j = 0;
newargv[j++] = python;
newargv[j++] = "-S";
newargv[j] = (char*)malloc(sizeof(char) * (
strlen(scriptdir) +
strlen(script) +
1));
strcpy(newargv[j], scriptdir);
strcat(newargv[j], script);
/* now tack on all the rest of the arguments. we can skip argv's
* first two arguments because, for cgi-wrapper there is only argv[0].
* For mail-wrapper, argv[1] is the mail command (e.g. post,
* mailowner, or mailcmd) and argv[2] is the listname. The mail
* command to execute gets passed in as this function's `script'
* parameter and becomes the argument to the python interpreter. The
* list name therefore should become argv[2] to this process.
*
* TBD: have to make sure this works with alias-wrapper.
*/
for (i=2, j++; i < argc; i++)
newargv[j++] = argv[i];
newargv[j] = NULL;
/* return always means failure */
(void)execve(python, &newargv[0], &newenv[0]);
return EXECVE_FAILURE;
}
/*
* Local Variables:
* c-file-style: "python"
* indent-tabs-mode: nil
* End:
*/
|
