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#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <assert.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <pwd.h>
#include <grp.h>
#include "sockutil.h"
#include "qarsh_packet.h"
/*
* QA Remote Shell Daemon
*/
/* Globals */
struct sockaddr_in peername;
int child_exitted = 0;
int
setup_user(char *user, char *group)
{
struct passwd *pw;
struct group *grp;
if ((pw = getpwnam(user)) == NULL) {
syslog(LOG_WARNING, "User \"%s\" not found\n", user);
return 0;
}
if (group && (grp = getgrnam(group))) {
setgid(grp->gr_gid);
initgroups(pw->pw_name, grp->gr_gid);
} else {
setgid(pw->pw_gid);
initgroups(pw->pw_name, pw->pw_gid);
}
/* setuid is last so we can still do setgid and initgroups */
setuid(pw->pw_uid);
return 1;
}
void
sig_handler(int sig)
{
if (sig == SIGCHLD) child_exitted++;
}
pid_t
run_cmd(const char *cmd, int p_in, int p_out, int p_err)
{
pid_t pid;
int new_in, new_out, new_err;
syslog(LOG_INFO, "Running cmdline: %s\n", cmd);
if ((pid = fork()) < 0) {
syslog(LOG_WARNING,
"Could not fork() in run_cmd(): %s\n", strerror(errno));
exit(1);
}
if (pid == 0) { /* child */
setpgrp();
/* Connect stdin, stdout, and stderr to qarsh */
new_in = connect_to_peer(&peername, p_in);
if (new_in == -1) syslog(LOG_WARNING, "connect to new_in failed");
dup2(new_in, fileno(stdin));
new_out = connect_to_peer(&peername, p_out);
if (new_out == -1) syslog(LOG_WARNING, "connect to new_out failed");
dup2(new_out, fileno(stdout));
new_err = connect_to_peer(&peername, p_err);
if (new_err == -1) syslog(LOG_WARNING, "connect to new_err failed");
dup2(new_err, fileno(stderr));
execlp("sh", "sh", "-c", cmd, NULL);
printf("exec of %s failed: %d, %s\n", cmd, errno, strerror(errno));
exit(127);
}
return pid;
}
void
handle_packets(int infd)
{
fd_set rfds;
int nfd;
struct timespec timeout;
struct qa_packet *qp = NULL, *rp = NULL;
sigset_t sigmask, orig_sigmask;
struct sigaction sa;
pid_t child_pid = 0;
int child_status;
sigemptyset(&sigmask);
sigaddset(&sigmask, SIGCHLD);
sigprocmask(SIG_BLOCK, &sigmask, &orig_sigmask);
sa.sa_handler = sig_handler;
sa.sa_mask = sigmask;
sa.sa_flags = SA_RESTART;
sigaction(SIGCHLD, &sa, NULL);
for (;;) {
FD_SET(infd, &rfds);
timeout.tv_sec = 3;
nfd = pselect(infd+1, &rfds, NULL, NULL, &timeout, &orig_sigmask);
if (child_exitted) {
waitpid(child_pid, &child_status, 0);
child_exitted--;
rp = make_qp_cmdexit(child_pid, child_status);
send_packet(fileno(stdout), rp);
qpfree(rp);
}
if (nfd < 0) {
if (errno == EINTR) {
/* signals handled above here */
continue;
} else {
syslog(LOG_ERR, "select errno %d, %s\n",
errno, strerror(errno));
}
} else if (nfd > 0) {
qp = recv_packet(infd);
if (qp == NULL) {
syslog(LOG_INFO, "That's enough\n");
break;
}
switch (qp->qp_type) {
case QP_KILL:
if (child_pid) {
syslog(LOG_INFO, "Sending child %d signal %d",
child_pid, qp->qp_kill.qp_sig);
kill(child_pid * -1, qp->qp_kill.qp_sig);
}
break;
case QP_SETUSER:
if (setup_user(qp->qp_setuser.qp_user,
qp->qp_setuser.qp_group) == 0) {
rp = make_qp_returncode(-1, 0, "User not found");
} else {
rp = make_qp_ack(QP_SETUSER, 1);
}
send_packet(fileno(stdout), rp);
qpfree(rp);
break;
case QP_RUNCMD:
child_pid = run_cmd(qp->qp_runcmd.qp_cmdline,
qp->qp_runcmd.qp_stdin_port,
qp->qp_runcmd.qp_stdout_port,
qp->qp_runcmd.qp_stderr_port);
break;
default:
syslog(LOG_WARNING,
"Packet type %s unimplemented",
qp_packet_type(qp->qp_type));
}
} else {
syslog(LOG_DEBUG, "Nothing to do\n");
}
}
}
int
main(int argc, char *argv[])
{
int ch;
socklen_t peernamelen;
openlog("qarshd", LOG_PID, LOG_DAEMON);
while ((ch = getopt(argc, argv, "")) != -1) {
switch (ch) {
case '?':
default:
printf("unknown option '%c'\n", optopt);
exit(1);
}
}
/* daemon initialization */
peernamelen = sizeof peername;
getpeername(0, (struct sockaddr *)&peername, &peernamelen);
syslog(LOG_INFO, "Talking to peer %s:%d",
inet_ntoa(peername.sin_addr), ntohs(peername.sin_port));
/* Start reading packets from stdin */
handle_packets(0);
return 0;
}
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