// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1992 Darren Senn
*/
/* These are all the functions necessary to implement itimers */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/syscalls.h>
#include <linux/time.h>
#include <linux/sched/signal.h>
#include <linux/sched/cputime.h>
#include <linux/posix-timers.h>
#include <linux/hrtimer.h>
#include <trace/events/timer.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
/**
* itimer_get_remtime - get remaining time for the timer
*
* @timer: the timer to read
*
* Returns the delta between the expiry time and now, which can be
* less than zero or 1usec for an pending expired timer
*/
static struct timespec64 itimer_get_remtime(struct hrtimer *timer)
{
ktime_t rem = __hrtimer_get_remaining(timer, true);
/*
* Racy but safe: if the itimer expires after the above
* hrtimer_get_remtime() call but before this condition
* then we return 0 - which is correct.
*/
if (hrtimer_active(timer)) {
if (rem <= 0)
rem = NSEC_PER_USEC;
} else
rem = 0;
return ktime_to_timespec64(rem);
}
static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
struct itimerspec64 *const value)
{
u64 val, interval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
spin_lock_irq(&tsk->sighand->siglock);
val = it->expires;
interval = it->incr;
if (val) {
u64 t, samples[CPUCLOCK_MAX];
thread_group_sample_cputime(tsk, samples);
t = samples[clock_id];
if (val < t)
/* about to fire */
val = TICK_NSEC;
else
val -= t;
}
spin_unlock_irq(&tsk->sighand->siglock);
value->it_value = ns_to_timespec64(val);
value->it_interval = ns_to_timespec64(interval);
}
static int do_getitimer(int which, struct itimerspec64 *value)
{
struct task_struct *tsk = current;
switch (which) {
case ITIMER_REAL:
spin_lock_irq(&tsk->sighand->siglock);
value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
value->it_interval =
ktime_to_timespec64(tsk->signal->it_real_incr);
spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
break;
case ITIMER_PROF:
get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
break;
default:
return(-EINVAL);
}
return 0;
}
static int put_itimerval(struct __kernel_old_itimerval __user *o,
const struct itimerspec64 *i)
{
struct __kernel_old_itimerval v;
v.it_interval.tv_sec = i->it_interval.tv_sec;
v.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
v.it_value.tv_sec = i->it_value.tv_sec;
v.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
return copy_to_user(o, &v, sizeof(struct __kernel_old_itimerval)) ? -EFAULT : 0;
}
SYSCALL_DEFINE2(getitimer, int, which, struct __kernel_old_itimerval __user *, value)
{
struct itimerspec64 get_buffer;
int error = do_getitimer(which, &get_buffer);
if (!error && put_itimerval(value, &get_buffer))
error = -EFAULT;
return error;
}
#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
struct old_itimerval32 {
struct old_timeval32 it_interval;
struct old_timeval32 it_value;
};
static int put_old_itimerval32(struct old_itimerval32 __user *o,
const struct itimerspec64 *i)
{
struct old_itimerval32 v32;
v32.it_interval.tv_sec = i->it_interval.tv_sec;
v32.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
v32.it_value.tv_sec = i->it_value.tv_sec;
v32.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0;
}
COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
struct old_itimerval32 __user *, value)
{
struct itimerspec64 get_buffer;
int error = do_getitimer(which, &get_buffer);
if (!error && put_old_itimerval32(value, &get_buffer))
error = -EFAULT;
return error;
}
#endif
/*
* The timer is automagically restarted, when interval != 0
*/
enum hrtimer_restart it_real_fn(struct hrtimer *timer)
{
struct signal_struct *sig =
container_of(timer, struct signal_struct, real_timer);
struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
return HRTIMER_NORESTART;
}
static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
const struct itimerspec64 *const value,
struct itimerspec64 *const ovalue)
{
u64 oval, nval, ointerval, ninterval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
nval = timespec64_to_ns(&value->it_value);
ninterval = timespec64_to_ns(&value->it_interval);
spin_lock_irq(&tsk->sighand->siglock);
oval = it->expires;
ointerval = it->incr;
if (oval || nval) {
if (nval > 0)
nval += TICK_NSEC;
set_process_cpu_timer(tsk, clock_id, &nval, &oval);
}
it->expires = nval;
it->incr = ninterval;
trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
ovalue->it_value = ns_to_timespec64(oval);
ovalue->it_interval = ns_to_timespec64(ointerval);
}
}
/*
* Returns true if the timeval is in canonical form
*/
#define timeval_valid(t) \
(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
static int do_setitimer(int which, struct itimerspec64 *value,
struct itimerspec64 *ovalue)
{
struct task_struct *tsk = current;
struct hrtimer *timer;
ktime_t expires;
switch (which) {
case ITIMER_REAL:
again:
spin_lock_irq(&tsk->sighand->siglock);
timer = &tsk->signal->real_timer;
if (ovalue) {
ovalue->it_value = itimer_get_remtime(timer);
ovalue->it_interval
= ktime_to_timespec64(tsk->signal->it_real_incr);
}
/* We are sharing ->siglock with it_real_fn() */
if (hrtimer_try_to_cancel(timer) < 0) {
spin_unlock_irq(&tsk->sighand->siglock);
hrtimer_cancel_wait_running(timer);
goto again;
}
expires = timespec64_to_ktime(value->it_value);
if (expires != 0) {
tsk->signal->it_real_incr =
timespec64_to_ktime(value->it_interval);
hrtimer_start(timer, expires, HRTIMER_MODE_REL);
} else
tsk->signal->it_real_incr = 0;
trace_itimer_state(ITIMER_REAL, value, 0);
spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
break;
case ITIMER_PROF:
set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
break;
default:
return -EINVAL;
}
return 0;
}
#ifdef CONFIG_SECURITY_SELINUX
void clear_itimer(void)
{
struct itimerspec64 v = {};
int i;
for (i = 0; i < 3; i++)
do_setitimer(i, &v, NULL);
}
#endif
#ifdef __ARCH_WANT_SYS_ALARM
/**
* alarm_setitimer - set alarm in seconds
*
* @seconds: number of seconds until alarm
* 0 disables the alarm
*
* Returns the remaining time in seconds of a pending timer or 0 when
* the timer is not active.
*
* On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
* negative timeval settings which would cause immediate expiry.
*/
static unsigned int alarm_setitimer(unsigned int seconds)
{
struct itimerspec64 it_new, it_old;
#if BITS_PER_LONG < 64
if (seconds > INT_MAX)
seconds = INT_MAX;
#endif
it_new.it_value.tv_sec = seconds;
it_new.it_value.tv_nsec = 0;
it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0;
do_setitimer(ITIMER_REAL, &it_new, &it_old);
/*
* We can't return 0 if we have an alarm pending ... And we'd
* better return too much than too little anyway
*/
if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
it_old.it_value.tv_sec++;
return it_old.it_value.tv_sec;
}
/*
* For backwards compatibility? This can be done in libc so Alpha
* and all newer ports shouldn't need it.
*/
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
{
return alarm_setitimer(seconds);
}
#endif
static int get_itimerval(struct itimerspec64 *o, const struct __kernel_old_itimerval __user *i)
{
struct __kernel_old_itimerval v;
if (copy_from_user(&v, i, sizeof(struct __kernel_old_itimerval)))
return -EFAULT;
/* Validate the timevals in value. */
if (!timeval_valid(&v.it_value) ||
!timeval_valid(&v.it_interval))
return -EINVAL;
o->it_interval.tv_sec = v.it_interval.tv_sec;
o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC;
o->it_value.tv_sec = v.it_value.tv_sec;
o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC;
return 0;
}
SYSCALL_DEFINE3(setitimer, int, which, struct __kernel_old_itimerval __user *, value,
struct __kernel_old_itimerval __user *, ovalue)
{
struct itimerspec64 set_buffer, get_buffer;
int error;
if (value) {
error = get_itimerval(&set_buffer, value);
if (error)
return error;
} else {
memset(&set_buffer, 0, sizeof(set_buffer));
printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
" Misfeature support will be removed\n",
current->comm);
}
error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
if (error || !ovalue)
return error;
if (put_itimerval(ovalue, &get_buffer))
return -EFAULT;
return 0;
}
#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i)
{
struct old_itimerval32 v32;
if (copy_from_user(&v32, i, sizeof(struct old_itimerval32)))
return -EFAULT;
/* Validate the timevals in value. */
if (!timeval_valid(&v32.it_value) ||
!timeval_valid(&v32.it_interval))
return -EINVAL;
o->it_interval.tv_sec = v32.it_interval.tv_sec;
o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC;
o->it_value.tv_sec = v32.it_value.tv_sec;
o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC;
return 0;
}
COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
struct old_itimerval32 __user *, value,
struct old_itimerval32 __user *, ovalue)
{
struct itimerspec64 set_buffer, get_buffer;
int error;
if (value) {
error = get_old_itimerval32(&set_buffer, value);
if (error)
return error;
} else {
memset(&set_buffer, 0, sizeof(set_buffer));
printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
" Misfeature support will be removed\n",
current->comm);
}
error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
if (error || !ovalue)
return error;
if (put_old_itimerval32(ovalue, &get_buffer))
return -EFAULT;
return 0;
}
#endif
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