From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/timerfd.c | 612 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 612 insertions(+) create mode 100644 fs/timerfd.c (limited to 'fs/timerfd.c') diff --git a/fs/timerfd.c b/fs/timerfd.c new file mode 100644 index 000000000..e9c96a0c7 --- /dev/null +++ b/fs/timerfd.c @@ -0,0 +1,612 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/timerfd.c + * + * Copyright (C) 2007 Davide Libenzi + * + * + * Thanks to Thomas Gleixner for code reviews and useful comments. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 -- cgit v1.2.3