// 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 /* * Invoked from dequeue_signal() when SIG_ALRM is delivered. * * Restart the ITIMER_REAL timer if it is armed as periodic timer.  Doing * this in the signal delivery path instead of self rearming prevents a DoS * with small increments in the high reolution timer case and reduces timer * noise in general. */void posixtimer_rearm_itimer(struct task_struct *tsk){	struct hrtimer *tmr = &tsk->signal->real_timer; 	if (!hrtimer_is_queued(tmr) && tsk->signal->it_real_incr != 0) {		hrtimer_forward(tmr, tmr->base->get_time(),				tsk->signal->it_real_incr);		hrtimer_restart(tmr);	}} /* * Interval timers are restarted in the signal delivery path.  See * posixtimer_rearm_itimer(). */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_SELINUXvoid 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