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/*
* Created by yuuta on 12/23/22.
*/
#include "common.h"
#include "log.h"
#define IOCTL(a, b, ...) \
if (ioctl(a, b, __VA_ARGS__) < 0) { LOGFV("ioctl(%d, 0x%x): %m", a, b, errno); return errno; }
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <limits.h>
#include <bsd/unistd.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <linux/kd.h>
#include <linux/vt.h>
static const char *conspath[] = {
"/proc/self/fd/0",
"/proc/self/fd/1",
"/proc/self/fd/2",
"/dev/tty",
"/dev/tty0",
"/dev/vc/0",
"/dev/systty",
"/dev/console"
};
static int fd_con = -1;
static struct vt_stat vts;
static char vt_dev[PATH_MAX + 1];
static int vt_fd = -1;
static pid_t chld = -1;
static int vt_switch(int to) {
if (to) {
IOCTL(fd_con, VT_ACTIVATE, p_env.vt)
IOCTL(fd_con, VT_WAITACTIVE, p_env.vt)
} else {
IOCTL(fd_con, VT_ACTIVATE, vts.v_active)
IOCTL(fd_con, VT_WAITACTIVE, vts.v_active)
}
return 0;
}
static int find_current_tty(void) {
for (unsigned int i = 0; i < sizeof(conspath) / sizeof(char *); i++) {
if ((fd_con = open(conspath[i], O_RDONLY)) == -1) {
LOGDV("Cannot open '%s': %m.",
conspath[i],
errno);
continue;
}
char arg;
errno = 0;
if (!isatty(fd_con) || ioctl(fd_con, KDGKBTYPE, &arg) ||
((arg != KB_101) && (arg != KB_84))) {
if (errno) {
LOGDV("Cannot open '%s': %m.",
conspath[i]);
} else {
LOGDV("Cannot open '%s': Not a TTY.", conspath[i]);
}
close(fd_con);
fd_con = -1;
continue;
}
LOGDV("Opened '%s': %d.", conspath[i], fd_con);
break;
}
if (fd_con == -1) {
LOGE("Cannot get the current console. Try running as root to get tty0.");
return 1;
}
return 0;
}
static int main_sak(void) {
setproctitle("sak");
/* We have to take the ownership here - otherwise SAK will kill the parent. */
if (setsid() == -1) {
LOGFV("Cannot set session ID: %m.", errno);
return errno;
}
int fd;
if ((fd = open(vt_dev, O_RDWR)) == -1) {
LOGFV("Cannot open '%s': %m.", vt_dev, errno);
return errno;
}
LOGDV("Opened '%s': %d.", vt_dev, fd);
IOCTL(fd, TIOCSCTTY, 0)
vt_switch(1);
dprintf(fd, "\033[r\033[H\033[J"
"Press SysRq + K to continue.\n");
/* Wait for signal. */
pause();
return 0;
}
int sd_setup(void) {
if (find_current_tty()) {
return 1;
}
IOCTL(fd_con, VT_GETSTATE, &vts)
IOCTL(fd_con, VT_OPENQRY, &p_env.vt)
snprintf(vt_dev, PATH_MAX, "/dev/tty%d", p_env.vt);
if (!(chld = fork())) {
exit(main_sak());
}
if (chld == -1) {
LOGFV("Cannot fork: %m.", errno);
return errno;
}
int chld_status = -1;
if (waitpid(chld, &chld_status, 0) != chld) {
LOGFV("Cannot wait for child: %m.", errno);
return errno;
}
if (!WIFSIGNALED(chld_status)) {
LOGF("Not killed by signal. Considered insecure.");
return 1;
}
switch (WTERMSIG(chld_status)) {
case SIGKILL: {
break;
}
case SIGINT:
case SIGTERM: {
return -1;
}
default: {
/* Consider insecure.
* Switch back and use the insecure view. */
LOGF("Killed by an incorrect signal. Considered insecure.");
return 1;
}
}
/* Take ownership */
if ((vt_fd = open(vt_dev, O_RDWR)) == -1) {
LOGFV("Cannot open '%s': %m.", vt_dev, errno);
return errno;
}
LOGDV("Opened '%s': %d.", vt_dev, vt_fd);
if (setsid() == -1) {
LOGFV("Cannot set session ID: %m.", errno);
return errno;
}
IOCTL(vt_fd, TIOCSCTTY, 1)
int in_bak, out_bak, err_bak;
if ((in_bak = dup(p_env.in)) == -1 ||
(out_bak = dup(p_env.out)) == -1 ||
(err_bak = dup(p_env.err)) == -1) {
LOGFV("dup: %m", errno);
return errno;
}
p_env.in = in_bak;
p_env.out = out_bak;
p_env.err = err_bak;
if (dup2(vt_fd, STDIN_FILENO) == -1 ||
dup2(vt_fd, STDOUT_FILENO) == -1 ||
dup2(vt_fd, STDERR_FILENO) == -1) {
LOGFV("dup2: %m", errno);
}
return 0;
}
void sd_cleanup(void) {
if (vt_fd >= 0) {
if (ioctl(vt_fd, TIOCNOTTY) < 0) {
LOGEV("Cannot deallocate console: %m", errno);
}
if (p_env.in != STDIN_FILENO) p_env.in = dup2(p_env.in, STDIN_FILENO);
if (p_env.out != STDOUT_FILENO) p_env.out = dup2(p_env.out, STDOUT_FILENO);
if (p_env.err != STDERR_FILENO) p_env.err = dup2(p_env.err, STDERR_FILENO);
/* It should already be closed? */
close(vt_fd);
vt_fd = -1;
}
if (fd_con >= 0) {
if (vt_switch(0)) {
LOGEV("Cannot return to the previous console: %m", errno);
}
if (ioctl(fd_con, VT_DISALLOCATE, p_env.vt) < 0) {
LOGEV("Cannot deallocate console: %m", errno);
}
close(fd_con);
fd_con = -1;
}
}
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