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
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
|
// 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 linux
import (
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/binary"
"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/kdefs"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
// Stat implements linux syscall stat(2).
func Stat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
statAddr := args[1].Pointer()
path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
if err != nil {
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return stat(t, d, dirPath, statAddr)
})
}
// Fstatat implements linux syscall newfstatat, i.e. fstatat(2).
func Fstatat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := kdefs.FD(args[0].Int())
addr := args[1].Pointer()
statAddr := args[2].Pointer()
flags := args[3].Int()
path, dirPath, err := copyInPath(t, addr, flags&linux.AT_EMPTY_PATH != 0)
if err != nil {
return 0, nil, err
}
if path == "" {
// Annoying. What's wrong with fstat?
file := t.FDMap().GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef()
return 0, nil, fstat(t, file, statAddr)
}
return 0, nil, fileOpOn(t, fd, path, flags&linux.AT_SYMLINK_NOFOLLOW == 0, func(root *fs.Dirent, d *fs.Dirent) error {
return stat(t, d, dirPath, statAddr)
})
}
// Lstat implements linux syscall lstat(2).
func Lstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
statAddr := args[1].Pointer()
path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
if err != nil {
return 0, nil, err
}
// If the path ends in a slash (i.e. dirPath is true), then we *do*
// want to resolve the final component.
resolve := dirPath
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, d *fs.Dirent) error {
return stat(t, d, dirPath, statAddr)
})
}
// Fstat implements linux syscall fstat(2).
func Fstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := kdefs.FD(args[0].Int())
statAddr := args[1].Pointer()
file := t.FDMap().GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef()
return 0, nil, fstat(t, file, statAddr)
}
// stat implements stat from the given *fs.Dirent.
func stat(t *kernel.Task, d *fs.Dirent, dirPath bool, statAddr usermem.Addr) error {
if dirPath && !fs.IsDir(d.Inode.StableAttr) {
return syserror.ENOTDIR
}
uattr, err := d.Inode.UnstableAttr(t)
if err != nil {
return err
}
return copyOutStat(t, statAddr, d.Inode.StableAttr, uattr)
}
// fstat implements fstat for the given *fs.File.
func fstat(t *kernel.Task, f *fs.File, statAddr usermem.Addr) error {
uattr, err := f.UnstableAttr(t)
if err != nil {
return err
}
return copyOutStat(t, statAddr, f.Dirent.Inode.StableAttr, uattr)
}
// copyOutStat copies the attributes (sattr, uattr) to the struct stat at
// address dst in t's address space. It encodes the stat struct to bytes
// manually, as stat() is a very common syscall for many applications, and
// t.CopyObjectOut has noticeable performance impact due to its many slice
// allocations and use of reflection.
func copyOutStat(t *kernel.Task, dst usermem.Addr, sattr fs.StableAttr, uattr fs.UnstableAttr) error {
var mode uint32
switch sattr.Type {
case fs.RegularFile, fs.SpecialFile:
mode |= linux.ModeRegular
case fs.Symlink:
mode |= linux.ModeSymlink
case fs.Directory, fs.SpecialDirectory:
mode |= linux.ModeDirectory
case fs.Pipe:
mode |= linux.ModeNamedPipe
case fs.CharacterDevice:
mode |= linux.ModeCharacterDevice
case fs.BlockDevice:
mode |= linux.ModeBlockDevice
case fs.Socket:
mode |= linux.ModeSocket
}
b := t.CopyScratchBuffer(int(linux.SizeOfStat))[:0]
// Dev (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.DeviceID))
// Ino (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.InodeID))
// Nlink (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uattr.Links)
// Mode (uint32)
b = binary.AppendUint32(b, usermem.ByteOrder, mode|uint32(uattr.Perms.LinuxMode()))
// UID (uint32)
b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()))
// GID (uint32)
b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()))
// Padding (uint32)
b = binary.AppendUint32(b, usermem.ByteOrder, 0)
// Rdev (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(linux.MakeDeviceID(sattr.DeviceFileMajor, sattr.DeviceFileMinor)))
// Size (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Size))
// Blksize (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(sattr.BlockSize))
// Blocks (uint64)
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Usage/512))
// ATime
atime := uattr.AccessTime.Timespec()
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Sec))
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Nsec))
// MTime
mtime := uattr.ModificationTime.Timespec()
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Sec))
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Nsec))
// CTime
ctime := uattr.StatusChangeTime.Timespec()
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Sec))
b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Nsec))
_, err := t.CopyOutBytes(dst, b)
return err
}
// Statfs implements linux syscall statfs(2).
func Statfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
statfsAddr := args[1].Pointer()
path, _, err := copyInPath(t, addr, false /* allowEmpty */)
if err != nil {
return 0, nil, err
}
return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
return statfsImpl(t, d, statfsAddr)
})
}
// Fstatfs implements linux syscall fstatfs(2).
func Fstatfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := kdefs.FD(args[0].Int())
statfsAddr := args[1].Pointer()
file := t.FDMap().GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef()
return 0, nil, statfsImpl(t, file.Dirent, statfsAddr)
}
// statfsImpl implements the linux syscall statfs and fstatfs based on a Dirent,
// copying the statfs structure out to addr on success, otherwise an error is
// returned.
func statfsImpl(t *kernel.Task, d *fs.Dirent, addr usermem.Addr) error {
info, err := d.Inode.StatFS(t)
if err != nil {
return err
}
// Construct the statfs structure and copy it out.
statfs := linux.Statfs{
Type: info.Type,
// Treat block size and fragment size as the same, as
// most consumers of this structure will expect one
// or the other to be filled in.
BlockSize: d.Inode.StableAttr.BlockSize,
Blocks: info.TotalBlocks,
// We don't have the concept of reserved blocks, so
// report blocks free the same as available blocks.
// This is a normal thing for filesystems, to do, see
// udf, hugetlbfs, tmpfs, among others.
BlocksFree: info.FreeBlocks,
BlocksAvailable: info.FreeBlocks,
Files: info.TotalFiles,
FilesFree: info.FreeFiles,
// Same as Linux for simple_statfs, see fs/libfs.c.
NameLength: linux.NAME_MAX,
FragmentSize: d.Inode.StableAttr.BlockSize,
// Leave other fields 0 like simple_statfs does.
}
if _, err := t.CopyOut(addr, &statfs); err != nil {
return err
}
return nil
}
|
