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/* common.c --- Common routines, constants, etc. Used by all the wrappers.
*
* Copyright (C) 1998-2005 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(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 removed from 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. 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* killenvars[] = {
"PYTHONPATH=",
"PYTHONHOME=",
"PATH=",
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 = &killenvars[0];
int keep = 1;
while (*k) {
if (!strncmp(*k, env[i], strlen(*k))) {
keep = 0;
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:
*/
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