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
|
package nametransform
import (
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"syscall"
"github.com/rfjakob/gocryptfs/internal/cryptocore"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const (
// DirIVLen is identical to AES block size
DirIVLen = 16
// DirIVFilename is the filename used to store directory IV.
// Exported because we have to ignore this name in directory listing.
DirIVFilename = "gocryptfs.diriv"
)
// ReadDirIVAt reads "gocryptfs.diriv" from the directory that is opened as "dirfd".
// Using the dirfd makes it immune to concurrent renames of the directory.
// Retries on EINTR.
func ReadDirIVAt(dirfd int) (iv []byte, err error) {
fdRaw, err := syscallcompat.Openat(dirfd, DirIVFilename,
syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
if err != nil {
return nil, err
}
fd := os.NewFile(uintptr(fdRaw), DirIVFilename)
defer fd.Close()
return fdReadDirIV(fd)
}
// allZeroDirIV is preallocated to quickly check if the data read from disk is all zero
var allZeroDirIV = make([]byte, DirIVLen)
// fdReadDirIV reads and verifies the DirIV from an opened gocryptfs.diriv file.
func fdReadDirIV(fd *os.File) (iv []byte, err error) {
// We want to detect if the file is bigger than DirIVLen, so
// make the buffer 1 byte bigger than necessary.
iv = make([]byte, DirIVLen+1)
n, err := fd.Read(iv)
if err != nil && err != io.EOF {
return nil, fmt.Errorf("read failed: %v", err)
}
iv = iv[0:n]
if len(iv) != DirIVLen {
return nil, fmt.Errorf("wanted %d bytes, got %d", DirIVLen, len(iv))
}
if bytes.Equal(iv, allZeroDirIV) {
return nil, fmt.Errorf("diriv is all-zero")
}
return iv, nil
}
// WriteDirIVAt - create a new gocryptfs.diriv file in the directory opened at
// "dirfd". On error we try to delete the incomplete file.
// This function is exported because it is used from fusefrontend, main,
// and also the automated tests.
func WriteDirIVAt(dirfd int) error {
// It makes sense to have the diriv files group-readable so the FS can
// be mounted from several users from a network drive (see
// https://github.com/rfjakob/gocryptfs/issues/387 ).
//
// Note that gocryptfs.conf is still created with 0400 permissions so the
// owner must explicitly chmod it to permit access.
const dirivPerms = 0440
iv := cryptocore.RandBytes(DirIVLen)
// 0400 permissions: gocryptfs.diriv should never be modified after creation.
// Don't use "ioutil.WriteFile", it causes trouble on NFS:
// https://github.com/rfjakob/gocryptfs/commit/7d38f80a78644c8ec4900cc990bfb894387112ed
fd, err := syscallcompat.Openat(dirfd, DirIVFilename, os.O_WRONLY|os.O_CREATE|os.O_EXCL, dirivPerms)
if err != nil {
tlog.Warn.Printf("WriteDirIV: Openat: %v", err)
return err
}
// Wrap the fd in an os.File - we need the write retry logic.
f := os.NewFile(uintptr(fd), DirIVFilename)
_, err = f.Write(iv)
if err != nil {
f.Close()
// It is normal to get ENOSPC here
if !syscallcompat.IsENOSPC(err) {
tlog.Warn.Printf("WriteDirIV: Write: %v", err)
}
// Delete incomplete gocryptfs.diriv file
syscallcompat.Unlinkat(dirfd, DirIVFilename, 0)
return err
}
err = f.Close()
if err != nil {
tlog.Warn.Printf("WriteDirIV: Close: %v", err)
// Delete incomplete gocryptfs.diriv file
syscallcompat.Unlinkat(dirfd, DirIVFilename, 0)
return err
}
return nil
}
// encryptAndHashName encrypts "name" and hashes it to a longname if it is
// too long.
// Returns ENAMETOOLONG if "name" is longer than 255 bytes.
func (be *NameTransform) EncryptAndHashName(name string, iv []byte) (string, error) {
// Prevent the user from creating files longer than 255 chars.
if len(name) > NameMax {
return "", syscall.ENAMETOOLONG
}
cName := be.EncryptName(name, iv)
if be.longNames && len(cName) > NameMax {
return be.HashLongName(cName), nil
}
return cName, nil
}
// Dir is like filepath.Dir but returns "" instead of ".".
func Dir(path string) string {
d := filepath.Dir(path)
if d == "." {
return ""
}
return d
}
|
