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
|
// 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 proc
import (
"bytes"
"fmt"
"sort"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
)
// forEachMountSource runs f for the process root mount and each mount that is a
// descendant of the root.
func forEachMountSource(t *kernel.Task, fn func(string, *fs.MountSource)) {
var fsctx *kernel.FSContext
t.WithMuLocked(func(t *kernel.Task) {
fsctx = t.FSContext()
})
if fsctx == nil {
// The task has been destroyed. Nothing to show here.
return
}
// All mount points must be relative to the rootDir, and mounts outside
// will be excluded.
rootDir := fsctx.RootDirectory()
if rootDir == nil {
// The task has been destroyed. Nothing to show here.
return
}
defer rootDir.DecRef()
if rootDir.Inode == nil {
panic(fmt.Sprintf("root dirent has nil inode: %+v", rootDir))
}
if rootDir.Inode.MountSource == nil {
panic(fmt.Sprintf("root dirent has nil mount: %+v", rootDir))
}
ms := append(rootDir.Inode.MountSource.Submounts(), rootDir.Inode.MountSource)
sort.Slice(ms, func(i, j int) bool {
return ms[i].ID() < ms[j].ID()
})
for _, m := range ms {
mroot := m.Root()
mountPath, desc := mroot.FullName(rootDir)
mroot.DecRef()
if !desc {
// MountSources that are not descendants of the chroot jail are ignored.
continue
}
fn(mountPath, m)
}
}
// mountInfoFile is used to implement /proc/[pid]/mountinfo.
//
// +stateify savable
type mountInfoFile struct {
t *kernel.Task
}
// NeedsUpdate implements SeqSource.NeedsUpdate.
func (mif *mountInfoFile) NeedsUpdate(_ int64) bool {
return true
}
// ReadSeqFileData implements SeqSource.ReadSeqFileData.
func (mif *mountInfoFile) ReadSeqFileData(ctx context.Context, handle seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
if handle != nil {
return nil, 0
}
var buf bytes.Buffer
forEachMountSource(mif.t, func(mountPath string, m *fs.MountSource) {
// Format:
// 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
// (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
// (1) MountSource ID.
fmt.Fprintf(&buf, "%d ", m.ID())
// (2) Parent ID (or this ID if there is no parent).
pID := m.ID()
if p := m.Parent(); p != nil {
pID = p.ID()
}
fmt.Fprintf(&buf, "%d ", pID)
// (3) Major:Minor device ID. We don't have a superblock, so we
// just use the root inode device number.
mroot := m.Root()
sa := mroot.Inode.StableAttr
mroot.DecRef()
fmt.Fprintf(&buf, "%d:%d ", sa.DeviceFileMajor, sa.DeviceFileMinor)
// (4) Root: the pathname of the directory in the filesystem
// which forms the root of this mount.
//
// NOTE: This will always be "/" until we implement
// bind mounts.
fmt.Fprintf(&buf, "/ ")
// (5) Mount point (relative to process root).
fmt.Fprintf(&buf, "%s ", mountPath)
// (6) Mount options.
opts := "rw"
if m.Flags.ReadOnly {
opts = "ro"
}
if m.Flags.NoAtime {
opts += ",noatime"
}
fmt.Fprintf(&buf, "%s ", opts)
// (7) Optional fields: zero or more fields of the form "tag[:value]".
// (8) Separator: the end of the optional fields is marked by a single hyphen.
fmt.Fprintf(&buf, "- ")
// (9) Filesystem type.
name := "none"
if m.Filesystem != nil {
name = m.Filesystem.Name()
}
fmt.Fprintf(&buf, "%s ", name)
// (10) Mount source: filesystem-specific information or "none".
fmt.Fprintf(&buf, "none ")
// (11) Superblock options. Only "ro/rw" is supported for now,
// and is the same as the filesystem option.
fmt.Fprintf(&buf, "%s\n", opts)
})
return []seqfile.SeqData{{Buf: buf.Bytes(), Handle: (*mountInfoFile)(nil)}}, 0
}
// mountsFile is used to implement /proc/[pid]/mountinfo.
//
// +stateify savable
type mountsFile struct {
t *kernel.Task
}
// NeedsUpdate implements SeqSource.NeedsUpdate.
func (mf *mountsFile) NeedsUpdate(_ int64) bool {
return true
}
// ReadSeqFileData implements SeqSource.ReadSeqFileData.
func (mf *mountsFile) ReadSeqFileData(ctx context.Context, handle seqfile.SeqHandle) ([]seqfile.SeqData, int64) {
if handle != nil {
return nil, 0
}
var buf bytes.Buffer
forEachMountSource(mf.t, func(mountPath string, m *fs.MountSource) {
// Format:
// <special device or remote filesystem> <mount point> <filesystem type> <mount options> <needs dump> <fsck order>
//
// We use the filesystem name as the first field, since there
// is no real block device we can point to, and we also should
// not expose anything about the remote filesystem.
//
// Only ro/rw option is supported for now.
//
// The "needs dump"and fsck flags are always 0, which is allowed.
opts := "rw"
if m.Flags.ReadOnly {
opts = "ro"
}
name := "none"
if m.Filesystem != nil {
name = m.Filesystem.Name()
}
fmt.Fprintf(&buf, "%s %s %s %s %d %d\n", "none", mountPath, name, opts, 0, 0)
})
return []seqfile.SeqData{{Buf: buf.Bytes(), Handle: (*mountsFile)(nil)}}, 0
}
|
