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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
// Copyright 2020 The gVisor Authors.
//
// 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 vfs2
import (
"math"
"time"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
// EpollCreate1 implements Linux syscall epoll_create1(2).
func EpollCreate1(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
flags := args[0].Int()
if flags&^linux.EPOLL_CLOEXEC != 0 {
return 0, nil, syserror.EINVAL
}
file, err := t.Kernel().VFS().NewEpollInstanceFD()
if err != nil {
return 0, nil, err
}
defer file.DecRef()
fd, err := t.NewFDFromVFS2(0, file, kernel.FDFlags{
CloseOnExec: flags&linux.EPOLL_CLOEXEC != 0,
})
if err != nil {
return 0, nil, err
}
return uintptr(fd), nil, nil
}
// EpollCreate implements Linux syscall epoll_create(2).
func EpollCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
size := args[0].Int()
// "Since Linux 2.6.8, the size argument is ignored, but must be greater
// than zero" - epoll_create(2)
if size <= 0 {
return 0, nil, syserror.EINVAL
}
file, err := t.Kernel().VFS().NewEpollInstanceFD()
if err != nil {
return 0, nil, err
}
defer file.DecRef()
fd, err := t.NewFDFromVFS2(0, file, kernel.FDFlags{})
if err != nil {
return 0, nil, err
}
return uintptr(fd), nil, nil
}
// EpollCtl implements Linux syscall epoll_ctl(2).
func EpollCtl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
epfd := args[0].Int()
op := args[1].Int()
fd := args[2].Int()
eventAddr := args[3].Pointer()
epfile := t.GetFileVFS2(epfd)
if epfile == nil {
return 0, nil, syserror.EBADF
}
defer epfile.DecRef()
ep, ok := epfile.Impl().(*vfs.EpollInstance)
if !ok {
return 0, nil, syserror.EINVAL
}
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef()
if epfile == file {
return 0, nil, syserror.EINVAL
}
var event linux.EpollEvent
switch op {
case linux.EPOLL_CTL_ADD:
if err := event.CopyIn(t, eventAddr); err != nil {
return 0, nil, err
}
return 0, nil, ep.AddInterest(file, fd, event)
case linux.EPOLL_CTL_DEL:
return 0, nil, ep.DeleteInterest(file, fd)
case linux.EPOLL_CTL_MOD:
if err := event.CopyIn(t, eventAddr); err != nil {
return 0, nil, err
}
return 0, nil, ep.ModifyInterest(file, fd, event)
default:
return 0, nil, syserror.EINVAL
}
}
// EpollWait implements Linux syscall epoll_wait(2).
func EpollWait(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
epfd := args[0].Int()
eventsAddr := args[1].Pointer()
maxEvents := int(args[2].Int())
timeout := int(args[3].Int())
const _EP_MAX_EVENTS = math.MaxInt32 / sizeofEpollEvent // Linux: fs/eventpoll.c:EP_MAX_EVENTS
if maxEvents <= 0 || maxEvents > _EP_MAX_EVENTS {
return 0, nil, syserror.EINVAL
}
epfile := t.GetFileVFS2(epfd)
if epfile == nil {
return 0, nil, syserror.EBADF
}
defer epfile.DecRef()
ep, ok := epfile.Impl().(*vfs.EpollInstance)
if !ok {
return 0, nil, syserror.EINVAL
}
// Use a fixed-size buffer in a loop, instead of make([]linux.EpollEvent,
// maxEvents), so that the buffer can be allocated on the stack.
var (
events [16]linux.EpollEvent
total int
ch chan struct{}
haveDeadline bool
deadline ktime.Time
)
for {
batchEvents := len(events)
if batchEvents > maxEvents {
batchEvents = maxEvents
}
n := ep.ReadEvents(events[:batchEvents])
maxEvents -= n
if n != 0 {
// Copy what we read out.
copiedEvents, err := copyOutEvents(t, eventsAddr, events[:n])
eventsAddr += usermem.Addr(copiedEvents * sizeofEpollEvent)
total += copiedEvents
if err != nil {
if total != 0 {
return uintptr(total), nil, nil
}
return 0, nil, err
}
// If we've filled the application's event buffer, we're done.
if maxEvents == 0 {
return uintptr(total), nil, nil
}
// Loop if we read a full batch, under the expectation that there
// may be more events to read.
if n == batchEvents {
continue
}
}
// We get here if n != batchEvents. If we read any number of events
// (just now, or in a previous iteration of this loop), or if timeout
// is 0 (such that epoll_wait should be non-blocking), return the
// events we've read so far to the application.
if total != 0 || timeout == 0 {
return uintptr(total), nil, nil
}
// In the first iteration of this loop, register with the epoll
// instance for readability events, but then immediately continue the
// loop since we need to retry ReadEvents() before blocking. In all
// subsequent iterations, block until events are available, the timeout
// expires, or an interrupt arrives.
if ch == nil {
var w waiter.Entry
w, ch = waiter.NewChannelEntry(nil)
epfile.EventRegister(&w, waiter.EventIn)
defer epfile.EventUnregister(&w)
} else {
// Set up the timer if a timeout was specified.
if timeout > 0 && !haveDeadline {
timeoutDur := time.Duration(timeout) * time.Millisecond
deadline = t.Kernel().MonotonicClock().Now().Add(timeoutDur)
haveDeadline = true
}
if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
if err == syserror.ETIMEDOUT {
err = nil
}
// total must be 0 since otherwise we would have returned
// above.
return 0, nil, err
}
}
}
}
// EpollPwait implements Linux syscall epoll_pwait(2).
func EpollPwait(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
maskAddr := args[4].Pointer()
maskSize := uint(args[5].Uint())
if err := setTempSignalSet(t, maskAddr, maskSize); err != nil {
return 0, nil, err
}
return EpollWait(t, args)
}
|
