forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
612 lines
14 KiB
612 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* fs/timerfd.c |
|
* |
|
* Copyright (C) 2007 Davide Libenzi <[email protected]> |
|
* |
|
* |
|
* Thanks to Thomas Gleixner for code reviews and useful comments. |
|
* |
|
*/ |
|
|
|
#include <linux/alarmtimer.h> |
|
#include <linux/file.h> |
|
#include <linux/poll.h> |
|
#include <linux/init.h> |
|
#include <linux/fs.h> |
|
#include <linux/sched.h> |
|
#include <linux/kernel.h> |
|
#include <linux/slab.h> |
|
#include <linux/list.h> |
|
#include <linux/spinlock.h> |
|
#include <linux/time.h> |
|
#include <linux/hrtimer.h> |
|
#include <linux/anon_inodes.h> |
|
#include <linux/timerfd.h> |
|
#include <linux/syscalls.h> |
|
#include <linux/compat.h> |
|
#include <linux/rcupdate.h> |
|
#include <linux/time_namespace.h> |
|
|
|
struct timerfd_ctx { |
|
union { |
|
struct hrtimer tmr; |
|
struct alarm alarm; |
|
} t; |
|
ktime_t tintv; |
|
ktime_t moffs; |
|
wait_queue_head_t wqh; |
|
u64 ticks; |
|
int clockid; |
|
short unsigned expired; |
|
short unsigned settime_flags; /* to show in fdinfo */ |
|
struct rcu_head rcu; |
|
struct list_head clist; |
|
spinlock_t cancel_lock; |
|
bool might_cancel; |
|
}; |
|
|
|
static LIST_HEAD(cancel_list); |
|
static DEFINE_SPINLOCK(cancel_lock); |
|
|
|
static inline bool isalarm(struct timerfd_ctx *ctx) |
|
{ |
|
return ctx->clockid == CLOCK_REALTIME_ALARM || |
|
ctx->clockid == CLOCK_BOOTTIME_ALARM; |
|
} |
|
|
|
/* |
|
* This gets called when the timer event triggers. We set the "expired" |
|
* flag, but we do not re-arm the timer (in case it's necessary, |
|
* tintv != 0) until the timer is accessed. |
|
*/ |
|
static void timerfd_triggered(struct timerfd_ctx *ctx) |
|
{ |
|
unsigned long flags; |
|
|
|
spin_lock_irqsave(&ctx->wqh.lock, flags); |
|
ctx->expired = 1; |
|
ctx->ticks++; |
|
wake_up_locked_poll(&ctx->wqh, EPOLLIN); |
|
spin_unlock_irqrestore(&ctx->wqh.lock, flags); |
|
} |
|
|
|
static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr) |
|
{ |
|
struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx, |
|
t.tmr); |
|
timerfd_triggered(ctx); |
|
return HRTIMER_NORESTART; |
|
} |
|
|
|
static enum alarmtimer_restart timerfd_alarmproc(struct alarm *alarm, |
|
ktime_t now) |
|
{ |
|
struct timerfd_ctx *ctx = container_of(alarm, struct timerfd_ctx, |
|
t.alarm); |
|
timerfd_triggered(ctx); |
|
return ALARMTIMER_NORESTART; |
|
} |
|
|
|
/* |
|
* Called when the clock was set to cancel the timers in the cancel |
|
* list. This will wake up processes waiting on these timers. The |
|
* wake-up requires ctx->ticks to be non zero, therefore we increment |
|
* it before calling wake_up_locked(). |
|
*/ |
|
void timerfd_clock_was_set(void) |
|
{ |
|
ktime_t moffs = ktime_mono_to_real(0); |
|
struct timerfd_ctx *ctx; |
|
unsigned long flags; |
|
|
|
rcu_read_lock(); |
|
list_for_each_entry_rcu(ctx, &cancel_list, clist) { |
|
if (!ctx->might_cancel) |
|
continue; |
|
spin_lock_irqsave(&ctx->wqh.lock, flags); |
|
if (ctx->moffs != moffs) { |
|
ctx->moffs = KTIME_MAX; |
|
ctx->ticks++; |
|
wake_up_locked_poll(&ctx->wqh, EPOLLIN); |
|
} |
|
spin_unlock_irqrestore(&ctx->wqh.lock, flags); |
|
} |
|
rcu_read_unlock(); |
|
} |
|
|
|
static void timerfd_resume_work(struct work_struct *work) |
|
{ |
|
timerfd_clock_was_set(); |
|
} |
|
|
|
static DECLARE_WORK(timerfd_work, timerfd_resume_work); |
|
|
|
/* |
|
* Invoked from timekeeping_resume(). Defer the actual update to work so |
|
* timerfd_clock_was_set() runs in task context. |
|
*/ |
|
void timerfd_resume(void) |
|
{ |
|
schedule_work(&timerfd_work); |
|
} |
|
|
|
static void __timerfd_remove_cancel(struct timerfd_ctx *ctx) |
|
{ |
|
if (ctx->might_cancel) { |
|
ctx->might_cancel = false; |
|
spin_lock(&cancel_lock); |
|
list_del_rcu(&ctx->clist); |
|
spin_unlock(&cancel_lock); |
|
} |
|
} |
|
|
|
static void timerfd_remove_cancel(struct timerfd_ctx *ctx) |
|
{ |
|
spin_lock(&ctx->cancel_lock); |
|
__timerfd_remove_cancel(ctx); |
|
spin_unlock(&ctx->cancel_lock); |
|
} |
|
|
|
static bool timerfd_canceled(struct timerfd_ctx *ctx) |
|
{ |
|
if (!ctx->might_cancel || ctx->moffs != KTIME_MAX) |
|
return false; |
|
ctx->moffs = ktime_mono_to_real(0); |
|
return true; |
|
} |
|
|
|
static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags) |
|
{ |
|
spin_lock(&ctx->cancel_lock); |
|
if ((ctx->clockid == CLOCK_REALTIME || |
|
ctx->clockid == CLOCK_REALTIME_ALARM) && |
|
(flags & TFD_TIMER_ABSTIME) && (flags & TFD_TIMER_CANCEL_ON_SET)) { |
|
if (!ctx->might_cancel) { |
|
ctx->might_cancel = true; |
|
spin_lock(&cancel_lock); |
|
list_add_rcu(&ctx->clist, &cancel_list); |
|
spin_unlock(&cancel_lock); |
|
} |
|
} else { |
|
__timerfd_remove_cancel(ctx); |
|
} |
|
spin_unlock(&ctx->cancel_lock); |
|
} |
|
|
|
static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx) |
|
{ |
|
ktime_t remaining; |
|
|
|
if (isalarm(ctx)) |
|
remaining = alarm_expires_remaining(&ctx->t.alarm); |
|
else |
|
remaining = hrtimer_expires_remaining_adjusted(&ctx->t.tmr); |
|
|
|
return remaining < 0 ? 0: remaining; |
|
} |
|
|
|
static int timerfd_setup(struct timerfd_ctx *ctx, int flags, |
|
const struct itimerspec64 *ktmr) |
|
{ |
|
enum hrtimer_mode htmode; |
|
ktime_t texp; |
|
int clockid = ctx->clockid; |
|
|
|
htmode = (flags & TFD_TIMER_ABSTIME) ? |
|
HRTIMER_MODE_ABS: HRTIMER_MODE_REL; |
|
|
|
texp = timespec64_to_ktime(ktmr->it_value); |
|
ctx->expired = 0; |
|
ctx->ticks = 0; |
|
ctx->tintv = timespec64_to_ktime(ktmr->it_interval); |
|
|
|
if (isalarm(ctx)) { |
|
alarm_init(&ctx->t.alarm, |
|
ctx->clockid == CLOCK_REALTIME_ALARM ? |
|
ALARM_REALTIME : ALARM_BOOTTIME, |
|
timerfd_alarmproc); |
|
} else { |
|
hrtimer_init(&ctx->t.tmr, clockid, htmode); |
|
hrtimer_set_expires(&ctx->t.tmr, texp); |
|
ctx->t.tmr.function = timerfd_tmrproc; |
|
} |
|
|
|
if (texp != 0) { |
|
if (flags & TFD_TIMER_ABSTIME) |
|
texp = timens_ktime_to_host(clockid, texp); |
|
if (isalarm(ctx)) { |
|
if (flags & TFD_TIMER_ABSTIME) |
|
alarm_start(&ctx->t.alarm, texp); |
|
else |
|
alarm_start_relative(&ctx->t.alarm, texp); |
|
} else { |
|
hrtimer_start(&ctx->t.tmr, texp, htmode); |
|
} |
|
|
|
if (timerfd_canceled(ctx)) |
|
return -ECANCELED; |
|
} |
|
|
|
ctx->settime_flags = flags & TFD_SETTIME_FLAGS; |
|
return 0; |
|
} |
|
|
|
static int timerfd_release(struct inode *inode, struct file *file) |
|
{ |
|
struct timerfd_ctx *ctx = file->private_data; |
|
|
|
timerfd_remove_cancel(ctx); |
|
|
|
if (isalarm(ctx)) |
|
alarm_cancel(&ctx->t.alarm); |
|
else |
|
hrtimer_cancel(&ctx->t.tmr); |
|
kfree_rcu(ctx, rcu); |
|
return 0; |
|
} |
|
|
|
static __poll_t timerfd_poll(struct file *file, poll_table *wait) |
|
{ |
|
struct timerfd_ctx *ctx = file->private_data; |
|
__poll_t events = 0; |
|
unsigned long flags; |
|
|
|
poll_wait(file, &ctx->wqh, wait); |
|
|
|
spin_lock_irqsave(&ctx->wqh.lock, flags); |
|
if (ctx->ticks) |
|
events |= EPOLLIN; |
|
spin_unlock_irqrestore(&ctx->wqh.lock, flags); |
|
|
|
return events; |
|
} |
|
|
|
static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count, |
|
loff_t *ppos) |
|
{ |
|
struct timerfd_ctx *ctx = file->private_data; |
|
ssize_t res; |
|
u64 ticks = 0; |
|
|
|
if (count < sizeof(ticks)) |
|
return -EINVAL; |
|
spin_lock_irq(&ctx->wqh.lock); |
|
if (file->f_flags & O_NONBLOCK) |
|
res = -EAGAIN; |
|
else |
|
res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks); |
|
|
|
/* |
|
* If clock has changed, we do not care about the |
|
* ticks and we do not rearm the timer. Userspace must |
|
* reevaluate anyway. |
|
*/ |
|
if (timerfd_canceled(ctx)) { |
|
ctx->ticks = 0; |
|
ctx->expired = 0; |
|
res = -ECANCELED; |
|
} |
|
|
|
if (ctx->ticks) { |
|
ticks = ctx->ticks; |
|
|
|
if (ctx->expired && ctx->tintv) { |
|
/* |
|
* If tintv != 0, this is a periodic timer that |
|
* needs to be re-armed. We avoid doing it in the timer |
|
* callback to avoid DoS attacks specifying a very |
|
* short timer period. |
|
*/ |
|
if (isalarm(ctx)) { |
|
ticks += alarm_forward_now( |
|
&ctx->t.alarm, ctx->tintv) - 1; |
|
alarm_restart(&ctx->t.alarm); |
|
} else { |
|
ticks += hrtimer_forward_now(&ctx->t.tmr, |
|
ctx->tintv) - 1; |
|
hrtimer_restart(&ctx->t.tmr); |
|
} |
|
} |
|
ctx->expired = 0; |
|
ctx->ticks = 0; |
|
} |
|
spin_unlock_irq(&ctx->wqh.lock); |
|
if (ticks) |
|
res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks); |
|
return res; |
|
} |
|
|
|
#ifdef CONFIG_PROC_FS |
|
static void timerfd_show(struct seq_file *m, struct file *file) |
|
{ |
|
struct timerfd_ctx *ctx = file->private_data; |
|
struct timespec64 value, interval; |
|
|
|
spin_lock_irq(&ctx->wqh.lock); |
|
value = ktime_to_timespec64(timerfd_get_remaining(ctx)); |
|
interval = ktime_to_timespec64(ctx->tintv); |
|
spin_unlock_irq(&ctx->wqh.lock); |
|
|
|
seq_printf(m, |
|
"clockid: %d\n" |
|
"ticks: %llu\n" |
|
"settime flags: 0%o\n" |
|
"it_value: (%llu, %llu)\n" |
|
"it_interval: (%llu, %llu)\n", |
|
ctx->clockid, |
|
(unsigned long long)ctx->ticks, |
|
ctx->settime_flags, |
|
(unsigned long long)value.tv_sec, |
|
(unsigned long long)value.tv_nsec, |
|
(unsigned long long)interval.tv_sec, |
|
(unsigned long long)interval.tv_nsec); |
|
} |
|
#else |
|
#define timerfd_show NULL |
|
#endif |
|
|
|
#ifdef CONFIG_CHECKPOINT_RESTORE |
|
static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
|
{ |
|
struct timerfd_ctx *ctx = file->private_data; |
|
int ret = 0; |
|
|
|
switch (cmd) { |
|
case TFD_IOC_SET_TICKS: { |
|
u64 ticks; |
|
|
|
if (copy_from_user(&ticks, (u64 __user *)arg, sizeof(ticks))) |
|
return -EFAULT; |
|
if (!ticks) |
|
return -EINVAL; |
|
|
|
spin_lock_irq(&ctx->wqh.lock); |
|
if (!timerfd_canceled(ctx)) { |
|
ctx->ticks = ticks; |
|
wake_up_locked_poll(&ctx->wqh, EPOLLIN); |
|
} else |
|
ret = -ECANCELED; |
|
spin_unlock_irq(&ctx->wqh.lock); |
|
break; |
|
} |
|
default: |
|
ret = -ENOTTY; |
|
break; |
|
} |
|
|
|
return ret; |
|
} |
|
#else |
|
#define timerfd_ioctl NULL |
|
#endif |
|
|
|
static const struct file_operations timerfd_fops = { |
|
.release = timerfd_release, |
|
.poll = timerfd_poll, |
|
.read = timerfd_read, |
|
.llseek = noop_llseek, |
|
.show_fdinfo = timerfd_show, |
|
.unlocked_ioctl = timerfd_ioctl, |
|
}; |
|
|
|
static int timerfd_fget(int fd, struct fd *p) |
|
{ |
|
struct fd f = fdget(fd); |
|
if (!f.file) |
|
return -EBADF; |
|
if (f.file->f_op != &timerfd_fops) { |
|
fdput(f); |
|
return -EINVAL; |
|
} |
|
*p = f; |
|
return 0; |
|
} |
|
|
|
SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags) |
|
{ |
|
int ufd; |
|
struct timerfd_ctx *ctx; |
|
|
|
/* Check the TFD_* constants for consistency. */ |
|
BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC); |
|
BUILD_BUG_ON(TFD_NONBLOCK != O_NONBLOCK); |
|
|
|
if ((flags & ~TFD_CREATE_FLAGS) || |
|
(clockid != CLOCK_MONOTONIC && |
|
clockid != CLOCK_REALTIME && |
|
clockid != CLOCK_REALTIME_ALARM && |
|
clockid != CLOCK_BOOTTIME && |
|
clockid != CLOCK_BOOTTIME_ALARM)) |
|
return -EINVAL; |
|
|
|
if ((clockid == CLOCK_REALTIME_ALARM || |
|
clockid == CLOCK_BOOTTIME_ALARM) && |
|
!capable(CAP_WAKE_ALARM)) |
|
return -EPERM; |
|
|
|
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); |
|
if (!ctx) |
|
return -ENOMEM; |
|
|
|
init_waitqueue_head(&ctx->wqh); |
|
spin_lock_init(&ctx->cancel_lock); |
|
ctx->clockid = clockid; |
|
|
|
if (isalarm(ctx)) |
|
alarm_init(&ctx->t.alarm, |
|
ctx->clockid == CLOCK_REALTIME_ALARM ? |
|
ALARM_REALTIME : ALARM_BOOTTIME, |
|
timerfd_alarmproc); |
|
else |
|
hrtimer_init(&ctx->t.tmr, clockid, HRTIMER_MODE_ABS); |
|
|
|
ctx->moffs = ktime_mono_to_real(0); |
|
|
|
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx, |
|
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS)); |
|
if (ufd < 0) |
|
kfree(ctx); |
|
|
|
return ufd; |
|
} |
|
|
|
static int do_timerfd_settime(int ufd, int flags, |
|
const struct itimerspec64 *new, |
|
struct itimerspec64 *old) |
|
{ |
|
struct fd f; |
|
struct timerfd_ctx *ctx; |
|
int ret; |
|
|
|
if ((flags & ~TFD_SETTIME_FLAGS) || |
|
!itimerspec64_valid(new)) |
|
return -EINVAL; |
|
|
|
ret = timerfd_fget(ufd, &f); |
|
if (ret) |
|
return ret; |
|
ctx = f.file->private_data; |
|
|
|
if (isalarm(ctx) && !capable(CAP_WAKE_ALARM)) { |
|
fdput(f); |
|
return -EPERM; |
|
} |
|
|
|
timerfd_setup_cancel(ctx, flags); |
|
|
|
/* |
|
* We need to stop the existing timer before reprogramming |
|
* it to the new values. |
|
*/ |
|
for (;;) { |
|
spin_lock_irq(&ctx->wqh.lock); |
|
|
|
if (isalarm(ctx)) { |
|
if (alarm_try_to_cancel(&ctx->t.alarm) >= 0) |
|
break; |
|
} else { |
|
if (hrtimer_try_to_cancel(&ctx->t.tmr) >= 0) |
|
break; |
|
} |
|
spin_unlock_irq(&ctx->wqh.lock); |
|
|
|
if (isalarm(ctx)) |
|
hrtimer_cancel_wait_running(&ctx->t.alarm.timer); |
|
else |
|
hrtimer_cancel_wait_running(&ctx->t.tmr); |
|
} |
|
|
|
/* |
|
* If the timer is expired and it's periodic, we need to advance it |
|
* because the caller may want to know the previous expiration time. |
|
* We do not update "ticks" and "expired" since the timer will be |
|
* re-programmed again in the following timerfd_setup() call. |
|
*/ |
|
if (ctx->expired && ctx->tintv) { |
|
if (isalarm(ctx)) |
|
alarm_forward_now(&ctx->t.alarm, ctx->tintv); |
|
else |
|
hrtimer_forward_now(&ctx->t.tmr, ctx->tintv); |
|
} |
|
|
|
old->it_value = ktime_to_timespec64(timerfd_get_remaining(ctx)); |
|
old->it_interval = ktime_to_timespec64(ctx->tintv); |
|
|
|
/* |
|
* Re-program the timer to the new value ... |
|
*/ |
|
ret = timerfd_setup(ctx, flags, new); |
|
|
|
spin_unlock_irq(&ctx->wqh.lock); |
|
fdput(f); |
|
return ret; |
|
} |
|
|
|
static int do_timerfd_gettime(int ufd, struct itimerspec64 *t) |
|
{ |
|
struct fd f; |
|
struct timerfd_ctx *ctx; |
|
int ret = timerfd_fget(ufd, &f); |
|
if (ret) |
|
return ret; |
|
ctx = f.file->private_data; |
|
|
|
spin_lock_irq(&ctx->wqh.lock); |
|
if (ctx->expired && ctx->tintv) { |
|
ctx->expired = 0; |
|
|
|
if (isalarm(ctx)) { |
|
ctx->ticks += |
|
alarm_forward_now( |
|
&ctx->t.alarm, ctx->tintv) - 1; |
|
alarm_restart(&ctx->t.alarm); |
|
} else { |
|
ctx->ticks += |
|
hrtimer_forward_now(&ctx->t.tmr, ctx->tintv) |
|
- 1; |
|
hrtimer_restart(&ctx->t.tmr); |
|
} |
|
} |
|
t->it_value = ktime_to_timespec64(timerfd_get_remaining(ctx)); |
|
t->it_interval = ktime_to_timespec64(ctx->tintv); |
|
spin_unlock_irq(&ctx->wqh.lock); |
|
fdput(f); |
|
return 0; |
|
} |
|
|
|
SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags, |
|
const struct __kernel_itimerspec __user *, utmr, |
|
struct __kernel_itimerspec __user *, otmr) |
|
{ |
|
struct itimerspec64 new, old; |
|
int ret; |
|
|
|
if (get_itimerspec64(&new, utmr)) |
|
return -EFAULT; |
|
ret = do_timerfd_settime(ufd, flags, &new, &old); |
|
if (ret) |
|
return ret; |
|
if (otmr && put_itimerspec64(&old, otmr)) |
|
return -EFAULT; |
|
|
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE2(timerfd_gettime, int, ufd, struct __kernel_itimerspec __user *, otmr) |
|
{ |
|
struct itimerspec64 kotmr; |
|
int ret = do_timerfd_gettime(ufd, &kotmr); |
|
if (ret) |
|
return ret; |
|
return put_itimerspec64(&kotmr, otmr) ? -EFAULT : 0; |
|
} |
|
|
|
#ifdef CONFIG_COMPAT_32BIT_TIME |
|
SYSCALL_DEFINE4(timerfd_settime32, int, ufd, int, flags, |
|
const struct old_itimerspec32 __user *, utmr, |
|
struct old_itimerspec32 __user *, otmr) |
|
{ |
|
struct itimerspec64 new, old; |
|
int ret; |
|
|
|
if (get_old_itimerspec32(&new, utmr)) |
|
return -EFAULT; |
|
ret = do_timerfd_settime(ufd, flags, &new, &old); |
|
if (ret) |
|
return ret; |
|
if (otmr && put_old_itimerspec32(&old, otmr)) |
|
return -EFAULT; |
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE2(timerfd_gettime32, int, ufd, |
|
struct old_itimerspec32 __user *, otmr) |
|
{ |
|
struct itimerspec64 kotmr; |
|
int ret = do_timerfd_gettime(ufd, &kotmr); |
|
if (ret) |
|
return ret; |
|
return put_old_itimerspec32(&kotmr, otmr) ? -EFAULT : 0; |
|
} |
|
#endif
|
|
|