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/* -*- linux-c -*-
*
* staprun.c - SystemTap module loader
*
* 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.
*
* Copyright (C) 2005-2007 Red Hat, Inc.
*
*/
#include "staprun.h"
int inserted_module = 0;
/* used in dbug, _err and _perr */
char *__name__ = "staprun";
extern long delete_module(const char *, unsigned int);
static int
run_as(uid_t uid, gid_t gid, const char *path, char *const argv[])
{
pid_t pid;
int rstatus;
if ((pid = fork()) < 0) {
_perr("fork");
return -1;
}
else if (pid == 0) {
/* Make sure we run as the full user. If we're
* switching to a non-root user, this won't allow
* that process to switch back to root (since the
* original process is setuid). */
if (uid != getuid()) {
if (do_cap(CAP_SETGID, setresgid, gid, gid, gid) < 0) {
_perr("setresgid");
exit(1);
}
if (do_cap(CAP_SETUID, setresuid, uid, uid, uid) < 0) {
_perr("setresuid");
exit(1);
}
}
/* Actually run the command. */
if (execv(path, argv) < 0)
perror(path);
_exit(1);
}
if (waitpid(pid, &rstatus, 0) < 0)
return -1;
if (WIFEXITED(rstatus))
return WEXITSTATUS(rstatus);
return -1;
}
/* Keep the uid and gid settings because we will likely */
/* conditionally restore "-u" */
static int run_stapio(char **argv)
{
uid_t uid = getuid();
gid_t gid = getgid();
argv[0] = PKGLIBDIR "/stapio";
if (verbose >= 2) {
int i = 0;
err("execing: ");
while (argv[i]) {
err("%s ", argv[i]);
i++;
}
err("\n");
}
return run_as(uid, gid, argv[0], argv);
}
int init_staprun(void)
{
dbug(2, "init_staprun\n");
if (mountfs() < 0)
return -1;
/* We're done with CAP_SYS_ADMIN. */
drop_cap(CAP_SYS_ADMIN);
if (!attach_mod) {
if (insert_module() < 0)
return -1;
else
inserted_module = 1;
}
return 0;
}
static void cleanup(int rc)
{
/* Only cleanup once. */
static int done = 0;
if (done == 0)
done = 1;
else
return;
dbug(2, "rc=%d, inserted_module=%d\n", rc, inserted_module);
if (setpriority (PRIO_PROCESS, 0, 0) < 0)
_perr("setpriority");
/* rc == 2 means disconnected */
if (rc == 2)
return;
/* If we inserted the module and did not get rc==2, then */
/* we really want to remove it. */
if (inserted_module || rc == 3) {
long ret;
dbug(2, "removing module %s\n", modname);
ret = do_cap(CAP_SYS_MODULE, delete_module, modname, 0);
if (ret != 0)
err("Error removing module '%s': %s\n", modname, moderror(errno));
}
}
static void exit_cleanup(void)
{
dbug(2, "something exited...\n");
cleanup(1);
}
int main(int argc, char **argv)
{
int rc;
if (atexit(exit_cleanup)) {
_perr("cannot set exit function");
exit(1);
}
if (!init_cap())
return 1;
/* Get rid of a few standard environment variables (which */
/* might cause us to do unintended things). */
rc = unsetenv("IFS") || unsetenv("CDPATH") || unsetenv("ENV")
|| unsetenv("BASH_ENV");
if (rc) {
_perr("unsetenv failed");
exit(-1);
}
setup_signals();
parse_args(argc, argv);
if (buffer_size)
dbug(2, "Using a buffer of %u bytes.\n", buffer_size);
if (optind < argc) {
parse_modpath(argv[optind++]);
dbug(2, "modpath=\"%s\", modname=\"%s\"\n", modpath, modname);
}
if (optind < argc) {
if (attach_mod) {
err("ERROR: Cannot have module options with attach (-A).\n");
usage(argv[0]);
} else {
unsigned start_idx = 0;
while (optind < argc && start_idx+1 < MAXMODOPTIONS)
modoptions[start_idx++] = argv[optind++];
modoptions[start_idx] = NULL;
}
}
if (modpath == NULL || *modpath == '\0') {
err("ERROR: Need a module name or path to load.\n");
usage(argv[0]);
}
if (check_permissions() != 1)
usage(argv[0]);
/* now bump the priority */
rc = do_cap(CAP_SYS_NICE, setpriority, PRIO_PROCESS, 0, -10);
/* failure is not fatal in this case */
if (rc < 0)
_perr("setpriority");
/* We're done with CAP_SYS_NICE. */
drop_cap(CAP_SYS_NICE);
if (init_staprun())
exit(1);
setup_staprun_signals();
if (!attach_mod)
handle_symbols();
rc = run_stapio(argv);
cleanup(rc);
return 0;
}
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