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
|
// Copyright 2018 Google LLC
//
// 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 fasync provides FIOASYNC related functionality.
package fasync
import (
"sync"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
"gvisor.googlesource.com/gvisor/pkg/waiter"
)
// New creates a new FileAsync.
func New() fs.FileAsync {
return &FileAsync{}
}
// FileAsync sends signals when the registered file is ready for IO.
//
// +stateify savable
type FileAsync struct {
mu sync.Mutex `state:"nosave"`
e waiter.Entry
requester *auth.Credentials
// Only one of the following is allowed to be non-nil.
recipientPG *kernel.ProcessGroup
recipientTG *kernel.ThreadGroup
recipientT *kernel.Task
}
// Callback sends a signal.
func (a *FileAsync) Callback(e *waiter.Entry) {
a.mu.Lock()
if a.e.Callback == nil {
a.mu.Unlock()
return
}
t := a.recipientT
tg := a.recipientTG
if a.recipientPG != nil {
tg = a.recipientPG.Originator()
}
if tg != nil {
t = tg.Leader()
}
if t == nil {
// No recipient has been registered.
a.mu.Unlock()
return
}
c := t.Credentials()
// Logic from sigio_perm in fs/fcntl.c.
if a.requester.EffectiveKUID == 0 ||
a.requester.EffectiveKUID == c.SavedKUID ||
a.requester.EffectiveKUID == c.RealKUID ||
a.requester.RealKUID == c.SavedKUID ||
a.requester.RealKUID == c.RealKUID {
t.SendSignal(&arch.SignalInfo{
Signo: int32(linux.SIGIO),
// SEND_SIG_PRIV
Code: arch.SignalInfoKernel,
})
}
a.mu.Unlock()
}
// Register sets the file which will be monitored for IO events.
//
// The file must not be currently registered.
func (a *FileAsync) Register(w waiter.Waitable) {
a.mu.Lock()
defer a.mu.Unlock()
if a.e.Callback != nil {
panic("registering already registered file")
}
a.e.Callback = a
w.EventRegister(&a.e, waiter.EventIn|waiter.EventOut|waiter.EventErr|waiter.EventHUp)
}
// Unregister stops monitoring a file.
//
// The file must be currently registered.
func (a *FileAsync) Unregister(w waiter.Waitable) {
a.mu.Lock()
defer a.mu.Unlock()
if a.e.Callback == nil {
panic("unregistering unregistered file")
}
w.EventUnregister(&a.e)
a.e.Callback = nil
}
// Owner returns who is currently getting signals. All return values will be
// nil if no one is set to receive signals.
func (a *FileAsync) Owner() (*kernel.Task, *kernel.ThreadGroup, *kernel.ProcessGroup) {
a.mu.Lock()
defer a.mu.Unlock()
return a.recipientT, a.recipientTG, a.recipientPG
}
// SetOwnerTask sets the owner (who will receive signals) to a specified task.
// Only this owner will receive signals.
func (a *FileAsync) SetOwnerTask(requester *kernel.Task, recipient *kernel.Task) {
a.mu.Lock()
defer a.mu.Unlock()
a.requester = requester.Credentials()
a.recipientT = recipient
a.recipientTG = nil
a.recipientPG = nil
}
// SetOwnerThreadGroup sets the owner (who will receive signals) to a specified
// thread group. Only this owner will receive signals.
func (a *FileAsync) SetOwnerThreadGroup(requester *kernel.Task, recipient *kernel.ThreadGroup) {
a.mu.Lock()
defer a.mu.Unlock()
a.requester = requester.Credentials()
a.recipientT = nil
a.recipientTG = recipient
a.recipientPG = nil
}
// SetOwnerProcessGroup sets the owner (who will receive signals) to a
// specified process group. Only this owner will receive signals.
func (a *FileAsync) SetOwnerProcessGroup(requester *kernel.Task, recipient *kernel.ProcessGroup) {
a.mu.Lock()
defer a.mu.Unlock()
a.requester = requester.Credentials()
a.recipientT = nil
a.recipientTG = nil
a.recipientPG = recipient
}
|
