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// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package linux
import (
"syscall"
"time"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
const nsecPerSec = int64(time.Second)
// copyItimerValIn copies an ItimerVal from the untrusted app range to the
// kernel. The ItimerVal may be either 32 or 64 bits.
// A NULL address is allowed because because Linux allows
// setitimer(which, NULL, &old_value) which disables the timer.
// There is a KERN_WARN message saying this misfeature will be removed.
// However, that hasn't happened as of 3.19, so we continue to support it.
func copyItimerValIn(t *kernel.Task, addr usermem.Addr) (linux.ItimerVal, error) {
if addr == usermem.Addr(0) {
return linux.ItimerVal{}, nil
}
switch t.Arch().Width() {
case 8:
// Native size, just copy directly.
var itv linux.ItimerVal
if _, err := t.CopyIn(addr, &itv); err != nil {
return linux.ItimerVal{}, err
}
return itv, nil
default:
return linux.ItimerVal{}, syscall.ENOSYS
}
}
// copyItimerValOut copies an ItimerVal to the untrusted app range.
// The ItimerVal may be either 32 or 64 bits.
// A NULL address is allowed, in which case no copy takes place
func copyItimerValOut(t *kernel.Task, addr usermem.Addr, itv *linux.ItimerVal) error {
if addr == usermem.Addr(0) {
return nil
}
switch t.Arch().Width() {
case 8:
// Native size, just copy directly.
_, err := t.CopyOut(addr, itv)
return err
default:
return syscall.ENOSYS
}
}
func findTimer(t *kernel.Task, which int32) (*ktime.Timer, error) {
switch which {
case linux.ITIMER_REAL:
return t.ThreadGroup().Timer().RealTimer, nil
case linux.ITIMER_VIRTUAL:
return t.ThreadGroup().Timer().VirtualTimer, nil
case linux.ITIMER_PROF:
return t.ThreadGroup().Timer().ProfTimer, nil
default:
return nil, syscall.EINVAL
}
}
// Getitimer implements linux syscall getitimer(2).
func Getitimer(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := args[0].Int()
val := args[1].Pointer()
timer, err := findTimer(t, timerID)
if err != nil {
return 0, nil, err
}
value, interval := ktime.SpecFromSetting(timer.Get())
olditv := linux.ItimerVal{
Value: linux.DurationToTimeval(value),
Interval: linux.DurationToTimeval(interval),
}
return 0, nil, copyItimerValOut(t, val, &olditv)
}
// Setitimer implements linux syscall setitimer(2).
func Setitimer(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := args[0].Int()
newVal := args[1].Pointer()
oldVal := args[2].Pointer()
timer, err := findTimer(t, timerID)
if err != nil {
return 0, nil, err
}
itv, err := copyItimerValIn(t, newVal)
if err != nil {
return 0, nil, err
}
// Just like linux, we cap the timer value and interval with the max
// number that int64 can represent which is roughly 292 years.
s, err := ktime.SettingFromSpec(itv.Value.ToDuration(),
itv.Interval.ToDuration(), timer.Clock())
if err != nil {
return 0, nil, err
}
valueNS, intervalNS := ktime.SpecFromSetting(timer.Swap(s))
olditv := linux.ItimerVal{
Value: linux.DurationToTimeval(valueNS),
Interval: linux.DurationToTimeval(intervalNS),
}
return 0, nil, copyItimerValOut(t, oldVal, &olditv)
}
// Alarm implements linux syscall alarm(2).
func Alarm(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
duration := time.Duration(args[0].Uint()) * time.Second
timer := t.ThreadGroup().Timer().RealTimer
s, err := ktime.SettingFromSpec(duration, 0, timer.Clock())
if err != nil {
return 0, nil, err
}
value, _ := ktime.SpecFromSetting(timer.Swap(s))
sec := int64(value) / nsecPerSec
nsec := int64(value) % nsecPerSec
// We can't return 0 if we have an alarm pending ...
if (sec == 0 && nsec > 0) || nsec >= nsecPerSec/2 {
sec++
}
return uintptr(sec), nil, nil
}
// TimerCreate implements linux syscall timer_create(2).
func TimerCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
clockID := args[0].Int()
sevp := args[1].Pointer()
timerIDp := args[2].Pointer()
c, err := getClock(t, clockID)
if err != nil {
return 0, nil, err
}
var sev *linux.Sigevent
if sevp != 0 {
sev = &linux.Sigevent{}
if _, err = t.CopyIn(sevp, sev); err != nil {
return 0, nil, err
}
}
id, err := t.IntervalTimerCreate(c, sev)
if err != nil {
return 0, nil, err
}
if _, err := t.CopyOut(timerIDp, &id); err != nil {
t.IntervalTimerDelete(id)
return 0, nil, err
}
return uintptr(id), nil, nil
}
// TimerSettime implements linux syscall timer_settime(2).
func TimerSettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := linux.TimerID(args[0].Value)
flags := args[1].Int()
newValAddr := args[2].Pointer()
oldValAddr := args[3].Pointer()
var newVal linux.Itimerspec
if _, err := t.CopyIn(newValAddr, &newVal); err != nil {
return 0, nil, err
}
oldVal, err := t.IntervalTimerSettime(timerID, newVal, flags&linux.TIMER_ABSTIME != 0)
if err != nil {
return 0, nil, err
}
if oldValAddr != 0 {
if _, err := t.CopyOut(oldValAddr, &oldVal); err != nil {
return 0, nil, err
}
}
return 0, nil, nil
}
// TimerGettime implements linux syscall timer_gettime(2).
func TimerGettime(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := linux.TimerID(args[0].Value)
curValAddr := args[1].Pointer()
curVal, err := t.IntervalTimerGettime(timerID)
if err != nil {
return 0, nil, err
}
_, err = t.CopyOut(curValAddr, &curVal)
return 0, nil, err
}
// TimerGetoverrun implements linux syscall timer_getoverrun(2).
func TimerGetoverrun(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := linux.TimerID(args[0].Value)
o, err := t.IntervalTimerGetoverrun(timerID)
if err != nil {
return 0, nil, err
}
return uintptr(o), nil, nil
}
// TimerDelete implements linux syscall timer_delete(2).
func TimerDelete(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
timerID := linux.TimerID(args[0].Value)
return 0, nil, t.IntervalTimerDelete(timerID)
}
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