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
|
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build js && wasm
package os
import (
"errors"
"slices"
"syscall"
)
// checkPathEscapes reports whether name escapes the root.
//
// Due to the lack of openat, checkPathEscapes is subject to TOCTOU races
// when symlinks change during the resolution process.
func checkPathEscapes(r *Root, name string) error {
return checkPathEscapesInternal(r, name, false)
}
// checkPathEscapesLstat reports whether name escapes the root.
// It does not resolve symlinks in the final path component.
//
// Due to the lack of openat, checkPathEscapes is subject to TOCTOU races
// when symlinks change during the resolution process.
func checkPathEscapesLstat(r *Root, name string) error {
return checkPathEscapesInternal(r, name, true)
}
func checkPathEscapesInternal(r *Root, name string, lstat bool) error {
if r.root.closed.Load() {
return ErrClosed
}
parts, suffixSep, err := splitPathInRoot(name, nil, nil)
if err != nil {
return err
}
i := 0
symlinks := 0
base := r.root.name
for i < len(parts) {
if parts[i] == ".." {
// Resolve one or more parent ("..") path components.
end := i + 1
for end < len(parts) && parts[end] == ".." {
end++
}
count := end - i
if count > i {
return errPathEscapes
}
parts = slices.Delete(parts, i-count, end)
i -= count
base = r.root.name
for j := range i {
base = joinPath(base, parts[j])
}
continue
}
part := parts[i]
if i == len(parts)-1 {
if lstat {
break
}
part += suffixSep
}
next := joinPath(base, part)
fi, err := Lstat(next)
if err != nil {
if IsNotExist(err) {
return nil
}
return underlyingError(err)
}
if fi.Mode()&ModeSymlink != 0 {
link, err := Readlink(next)
if err != nil {
return errPathEscapes
}
symlinks++
if symlinks > rootMaxSymlinks {
return errors.New("too many symlinks")
}
newparts, newSuffixSep, err := splitPathInRoot(link, parts[:i], parts[i+1:])
if err != nil {
return err
}
if i == len(parts) {
// suffixSep contains any trailing path separator characters
// in the link target.
// If we are replacing the remainder of the path, retain these.
// If we're replacing some intermediate component of the path,
// ignore them, since intermediate components must always be
// directories.
suffixSep = newSuffixSep
}
parts = newparts
continue
}
if !fi.IsDir() && i < len(parts)-1 {
return syscall.ENOTDIR
}
base = next
i++
}
return nil
}
|
