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
|
package main
import (
"encoding/hex"
"flag"
"fmt"
"io"
"os"
"runtime"
"github.com/rfjakob/gocryptfs/v2/internal/configfile"
"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
"github.com/rfjakob/gocryptfs/v2/internal/cryptocore"
"github.com/rfjakob/gocryptfs/v2/internal/exitcodes"
"github.com/rfjakob/gocryptfs/v2/internal/fido2"
"github.com/rfjakob/gocryptfs/v2/internal/readpassword"
"github.com/rfjakob/gocryptfs/v2/internal/tlog"
)
// GitVersion is the gocryptfs version according to git, set by build.bash
var GitVersion = "[GitVersion not set - please compile using ./build.bash]"
// BuildDate is a date string like "2017-09-06", set by build.bash
var BuildDate = "0000-00-00"
const (
myName = "gocryptfs-xray"
)
// blockSize is the ciphertext block size including overheads
func blockSize(alg cryptocore.AEADTypeEnum) int {
return alg.NonceSize + contentenc.DefaultBS + cryptocore.AuthTagLen
}
func errExit(err error) {
fmt.Println(err)
os.Exit(1)
}
func prettyPrintHeader(h *contentenc.FileHeader, algo cryptocore.AEADTypeEnum) {
id := hex.EncodeToString(h.ID)
fmt.Printf("Header: Version: %d, Id: %s, assuming %s mode\n", h.Version, id, algo.Algo)
}
// printVersion prints a version string like this:
// gocryptfs v1.7-32-gcf99cfd; go-fuse v1.0.0-174-g22a9cb9; 2019-05-12 go1.12 linux/amd64
func printVersion() {
built := fmt.Sprintf("%s %s", BuildDate, runtime.Version())
fmt.Printf("%s %s; %s %s/%s\n",
myName, GitVersion, built,
runtime.GOOS, runtime.GOARCH)
}
func usage() {
printVersion()
fmt.Printf("\n")
fmt.Fprintf(os.Stderr, "Usage: %s [OPTIONS] FILE\n"+
"\n"+
"Options:\n", myName)
flag.PrintDefaults()
fmt.Fprintf(os.Stderr, "\n"+
"Examples:\n"+
" gocryptfs-xray myfs/mCXnISiv7nEmyc0glGuhTQ\n"+
" gocryptfs-xray -dumpmasterkey myfs/gocryptfs.conf\n"+
" gocryptfs-xray -encrypt-paths myfs.sock\n")
}
// sum counts the number of true values
func sum(x ...*bool) (s int) {
for _, v := range x {
if *v {
s++
}
}
return s
}
type argContainer struct {
dumpmasterkey *bool
decryptPaths *bool
encryptPaths *bool
aessiv *bool
xchacha *bool
sep0 *bool
fido2 *string
version *bool
}
func main() {
var args argContainer
args.dumpmasterkey = flag.Bool("dumpmasterkey", false, "Decrypt and dump the master key")
args.decryptPaths = flag.Bool("decrypt-paths", false, "Decrypt file paths using gocryptfs control socket")
args.encryptPaths = flag.Bool("encrypt-paths", false, "Encrypt file paths using gocryptfs control socket")
args.sep0 = flag.Bool("0", false, "Use \\0 instead of \\n as separator")
args.aessiv = flag.Bool("aessiv", false, "Assume AES-SIV mode instead of AES-GCM")
args.xchacha = flag.Bool("xchacha", false, "Assume XChaCha20-Poly1305 mode instead of AES-GCM")
args.fido2 = flag.String("fido2", "", "Protect the masterkey using a FIDO2 token instead of a password")
args.version = flag.Bool("version", false, "Print version information")
flag.Usage = usage
flag.Parse()
if *args.version {
printVersion()
os.Exit(0)
}
s := sum(args.dumpmasterkey, args.decryptPaths, args.encryptPaths)
if s > 1 {
fmt.Printf("fatal: %d operations were requested\n", s)
os.Exit(1)
}
if flag.NArg() != 1 {
usage()
os.Exit(1)
}
fn := flag.Arg(0)
if *args.decryptPaths {
decryptPaths(fn, *args.sep0)
}
if *args.encryptPaths {
encryptPaths(fn, *args.sep0)
}
f, err := os.Open(fn)
if err != nil {
errExit(err)
}
defer f.Close()
if *args.dumpmasterkey {
dumpMasterKey(fn, *args.fido2)
} else {
inspectCiphertext(&args, f)
}
}
func dumpMasterKey(fn string, fido2Path string) {
tlog.Info.Enabled = false
cf, err := configfile.Load(fn)
if err != nil {
fmt.Fprintln(os.Stderr, err)
exitcodes.Exit(err)
}
var pw []byte
if cf.IsFeatureFlagSet(configfile.FlagFIDO2) {
if fido2Path == "" {
tlog.Fatal.Printf("Masterkey encrypted using FIDO2 token; need to use the --fido2 option.")
os.Exit(exitcodes.Usage)
}
pw = fido2.Secret(fido2Path, cf.FIDO2.CredentialID, cf.FIDO2.HMACSalt)
} else {
pw, err = readpassword.Once(nil, nil, "")
if err != nil {
tlog.Fatal.Println(err)
os.Exit(exitcodes.ReadPassword)
}
}
masterkey, err := cf.DecryptMasterKey(pw)
// Purge password from memory
for i := range pw {
pw[i] = 0
}
if err != nil {
tlog.Fatal.Println(err)
os.Exit(exitcodes.LoadConf)
}
fmt.Println(hex.EncodeToString(masterkey))
// Purge masterkey from memory
for i := range masterkey {
masterkey[i] = 0
}
}
func inspectCiphertext(args *argContainer, fd *os.File) {
algo := cryptocore.BackendGoGCM
if *args.aessiv {
algo = cryptocore.BackendAESSIV
} else if *args.xchacha {
algo = cryptocore.BackendXChaCha20Poly1305
}
headerBytes := make([]byte, contentenc.HeaderLen)
n, err := fd.ReadAt(headerBytes, 0)
if err == io.EOF && n == 0 {
fmt.Println("empty file")
os.Exit(0)
} else if err == io.EOF {
fmt.Printf("incomplete file header: read %d bytes, want %d\n", n, contentenc.HeaderLen)
os.Exit(1)
} else if err != nil {
errExit(err)
}
header, err := contentenc.ParseHeader(headerBytes)
if err != nil {
errExit(err)
}
prettyPrintHeader(header, algo)
var i int64
buf := make([]byte, blockSize(algo))
for i = 0; ; i++ {
off := contentenc.HeaderLen + i*int64(blockSize(algo))
n, err := fd.ReadAt(buf, off)
if err != nil && err != io.EOF {
errExit(err)
}
if n == 0 && err == io.EOF {
break
}
// A block contains at least the IV, the Auth Tag and 1 data byte
if n < algo.NonceSize+cryptocore.AuthTagLen+1 {
errExit(fmt.Errorf("corrupt block: truncated data, len=%d", n))
}
data := buf[:n]
// Parse block data
iv := data[:algo.NonceSize]
tag := data[len(data)-cryptocore.AuthTagLen:]
if *args.aessiv {
tag = data[algo.NonceSize : algo.NonceSize+cryptocore.AuthTagLen]
}
fmt.Printf("Block %2d: IV: %s, Tag: %s, Offset: %5d Len: %d\n",
i, hex.EncodeToString(iv), hex.EncodeToString(tag), off, len(data))
}
}
|
