forked from apptainer/singularity
/
image.go
182 lines (159 loc) · 4.59 KB
/
image.go
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
// Copyright (c) 2018, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package image
import (
"fmt"
"os"
"path/filepath"
"strings"
"syscall"
"github.com/sylabs/singularity/internal/pkg/sylog"
"github.com/sylabs/singularity/internal/pkg/util/user"
)
const (
launchString = " run-singularity"
bufferSize = 2048
)
var registeredFormats = []struct {
name string
format format
}{
{"sif", &sifFormat{}},
{"sandbox", &sandboxFormat{}},
{"squashfs", &squashfsFormat{}},
{"ext3", &ext3Format{}},
}
// format describes the interface that an image format type must implement.
type format interface {
openMode(bool) int
initializer(*Image, os.FileInfo) error
}
// Image describes an image object
type Image struct {
Path string `json:"path"`
Name string `json:"name"`
Type int `json:"type"`
File *os.File `json:"-"`
Fd uintptr `json:"fd"`
Source string `json:"source"`
Offset uint64 `json:"offset"`
Size uint64 `json:"size"`
Writable bool `json:"writable"`
RootFS bool `json:"rootFS"`
}
// AuthorizedPath checks if image is in a path supplied in paths
func (i *Image) AuthorizedPath(paths []string) (bool, error) {
authorized := false
dirname := i.Path
for _, path := range paths {
match, err := filepath.EvalSymlinks(filepath.Clean(path))
if err != nil {
return authorized, fmt.Errorf("failed to resolve path %s: %s", path, err)
}
if strings.HasPrefix(dirname, match) {
authorized = true
break
}
}
return authorized, nil
}
// AuthorizedOwner checks if image is owned by user supplied in users list
func (i *Image) AuthorizedOwner(owners []string) (bool, error) {
authorized := false
fileinfo, err := i.File.Stat()
if err != nil {
return authorized, fmt.Errorf("failed to get stat for %s", i.Path)
}
uid := fileinfo.Sys().(*syscall.Stat_t).Uid
for _, owner := range owners {
pw, err := user.GetPwNam(owner)
if err != nil {
return authorized, fmt.Errorf("failed to retrieve user information for %s: %s", owner, err)
}
if pw.UID == uid {
authorized = true
break
}
}
return authorized, nil
}
// AuthorizedGroup checks if image is owned by group supplied in groups list
func (i *Image) AuthorizedGroup(groups []string) (bool, error) {
authorized := false
fileinfo, err := i.File.Stat()
if err != nil {
return authorized, fmt.Errorf("failed to get stat for %s", i.Path)
}
gid := fileinfo.Sys().(*syscall.Stat_t).Gid
for _, group := range groups {
gr, err := user.GetGrNam(group)
if err != nil {
return authorized, fmt.Errorf("failed to retrieve group information for %s: %s", group, err)
}
if gr.GID == gid {
authorized = true
break
}
}
return authorized, nil
}
// ResolvePath returns a resolved absolute path
func ResolvePath(path string) (string, error) {
abspath, err := filepath.Abs(path)
if err != nil {
return "", fmt.Errorf("failed to get absolute path: %s", err)
}
resolvedPath, err := filepath.EvalSymlinks(abspath)
if err != nil {
return "", fmt.Errorf("failed to retrieved path for %s: %s", path, err)
}
return resolvedPath, nil
}
// Init initilizes an image object based on given path
func Init(path string, writable bool) (*Image, error) {
sylog.Debugf("Entering image format intializer")
resolvedPath, err := ResolvePath(path)
if err != nil {
return nil, err
}
img := &Image{
Path: resolvedPath,
Name: filepath.Base(resolvedPath),
}
for _, rf := range registeredFormats {
sylog.Debugf("Check for image format %s", rf.name)
img.Writable = writable
mode := rf.format.openMode(writable)
if mode&os.O_RDWR != 0 {
if err := syscall.Access(resolvedPath, 2); err != nil {
sylog.Debugf("Opening %s in read-only mode: no write permissions", path)
mode = os.O_RDONLY
img.Writable = false
}
}
img.File, err = os.OpenFile(resolvedPath, mode, 0)
if err != nil {
continue
}
fileinfo, err := img.File.Stat()
if err != nil {
img.File.Close()
return nil, err
}
err = rf.format.initializer(img, fileinfo)
if err != nil {
sylog.Debugf("%s format initializer returns: %s", rf.name, err)
img.File.Close()
continue
}
if _, _, err := syscall.Syscall(syscall.SYS_FCNTL, img.File.Fd(), syscall.F_SETFD, syscall.O_CLOEXEC); err != 0 {
sylog.Warningf("failed to set O_CLOEXEC flags on image")
}
img.Source = fmt.Sprintf("/proc/self/fd/%d", img.File.Fd())
img.Fd = img.File.Fd()
return img, nil
}
return nil, fmt.Errorf("image format not recognized")
}