static mksh_uari_t
rndsetup(void)
{
register uint32_t h;
struct {
ALLOC_ITEM alloc_INT;
void *dataptr, *stkptr, *mallocptr;
#if defined(__GLIBC__) && (__GLIBC__ >= 2)
sigjmp_buf jbuf;
#endif
struct timeval tv;
} *bufptr;
char *cp;
cp = alloc(sizeof(*bufptr) - sizeof(ALLOC_ITEM), APERM);
/* clear the allocated space, for valgrind and to avoid UB */
memset(cp, 0, sizeof(*bufptr) - sizeof(ALLOC_ITEM));
/* undo what alloc() did to the malloc result address */
bufptr = (void *)(cp - sizeof(ALLOC_ITEM));
/* PIE or something similar provides us with deltas here */
bufptr->dataptr = &rndsetupstate;
/* ASLR in at least Windows, Linux, some BSDs */
bufptr->stkptr = &bufptr;
/* randomised malloc in BSD (and possibly others) */
bufptr->mallocptr = bufptr;
#if defined(__GLIBC__) && (__GLIBC__ >= 2)
/* glibc pointer guard */
sigsetjmp(bufptr->jbuf, 1);
#endif
/* introduce variation (and yes, second arg MBZ for portability) */
mksh_TIME(bufptr->tv);
#ifdef MKSH_ALLOC_CATCH_UNDERRUNS
mprotect(((char *)bufptr) + 4096, 4096, PROT_READ | PROT_WRITE);
#endif
h = chvt_rndsetup(bufptr, sizeof(*bufptr));
afree(cp, APERM);
return ((mksh_uari_t)h);
}
static void
chvt(const Getopt *go)
{
const char *dv = go->optarg;
char *cp = NULL;
int fd;
switch (*dv) {
case '-':
dv = "/dev/null";
break;
case '!':
++dv;
/* FALLTHROUGH */
default: {
struct stat sb;
if (stat(dv, &sb)) {
cp = shf_smprintf("/dev/ttyC%s", dv);
dv = cp;
if (stat(dv, &sb)) {
memmove(cp + 1, cp, /* /dev/tty */ 8);
dv = cp + 1;
if (stat(dv, &sb)) {
errorf("%s: %s: %s", "chvt",
"can't find tty", go->optarg);
}
}
}
if (!(sb.st_mode & S_IFCHR))
errorf("%s: %s: %s", "chvt", "not a char device", dv);
#ifndef MKSH_DISABLE_REVOKE_WARNING
#if HAVE_REVOKE
if (revoke(dv))
#endif
warningf(false, "%s: %s %s", "chvt",
"new shell is potentially insecure, can't revoke",
dv);
#endif
}
}
if ((fd = binopen2(dv, O_RDWR)) < 0) {
sleep(1);
if ((fd = binopen2(dv, O_RDWR)) < 0) {
errorf("%s: %s %s", "chvt", "can't open", dv);
}
}
if (go->optarg[0] != '!') {
switch (fork()) {
case -1:
errorf("%s: %s %s", "chvt", "fork", "failed");
case 0:
break;
default:
exit(0);
}
}
if (setsid() == -1)
errorf("%s: %s %s", "chvt", "setsid", "failed");
if (go->optarg[0] != '-') {
if (ioctl(fd, TIOCSCTTY, NULL) == -1)
errorf("%s: %s %s", "chvt", "TIOCSCTTY", "failed");
if (tcflush(fd, TCIOFLUSH))
errorf("%s: %s %s", "chvt", "TCIOFLUSH", "failed");
}
ksh_dup2(fd, 0, false);
ksh_dup2(fd, 1, false);
ksh_dup2(fd, 2, false);
if (fd > 2)
close(fd);
rndset((unsigned long)chvt_rndsetup(go, sizeof(Getopt)));
chvt_reinit();
}
