1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
// 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"
)
// ItimerType denotes the type of interval timer.
type ItimerType int
// Interval timer types from <sys/time.h>.
const (
// ItimerReal equals to ITIMER_REAL.
ItimerReal ItimerType = iota
// ItimerVirtual equals to ITIMER_VIRTUAL.
ItimerVirtual
// ItimerProf equals to ITIMER_PROF.
ItimerProf
)
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, w ItimerType) (*ktime.Timer, error) {
switch w {
case ItimerReal:
return t.ThreadGroup().Timer().RealTimer, nil
case ItimerVirtual:
return t.ThreadGroup().Timer().VirtualTimer, nil
case ItimerProf:
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 := ItimerType(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 := ItimerType(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
}
|
