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+/* common.c --- Common routines, constants, etc. Used by all the wrappers.
+ *
+ * Copyright (C) 1998,1999,2000,2001,2002 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 %s. Try adding this group\n"
+ "to your system, or re-run configure, providing an\n"
+ "existing group name with the command line option %s.",
+ parentgroup, option);
+
+ 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"
+ * End:
+ */