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
|
package main
import (
"bytes"
"context"
"crypto/sha256"
"crypto/x509"
"encoding/json"
"errors"
"fmt"
logger "log"
"net/http"
"os"
"time"
"git.cs.kau.se/rasmoste/ct-sans/internal/merkle"
ct "github.com/google/certificate-transparency-go"
"github.com/google/certificate-transparency-go/client"
"github.com/google/certificate-transparency-go/jsonclient"
"gitlab.torproject.org/rgdd/ct/pkg/metadata"
)
func snapshot(opts options) error {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
if err := os.MkdirAll(opts.Directory, os.ModePerm); err != nil {
return err
}
logger.Printf("INFO: updating metadata file\n")
source := metadata.NewHTTPSource(metadata.HTTPSourceOptions{Name: "google"})
msg, sig, md, err := source.Load(ctx)
if err != nil {
return err
}
if err := os.WriteFile(fmt.Sprintf("%s/%s", opts.Directory, opts.metadataFile), msg, 0644); err != nil {
return err
}
if err := os.WriteFile(fmt.Sprintf("%s/%s", opts.Directory, opts.metadataSignatureFile), sig, 0644); err != nil {
return err
}
timestamp := []byte(fmt.Sprintf("%d", time.Now().Unix()))
if err := os.WriteFile(fmt.Sprintf("%s/%s", opts.Directory, opts.metadataTimestampFile), timestamp, 0644); err != nil {
return err
}
logger.Printf("INFO: updating signed tree heads\n")
for _, log := range logs(md) {
id, _ := log.Key.ID()
der, _ := x509.MarshalPKIXPublicKey(log.Key)
dir := fmt.Sprintf("%s/%x", opts.logDirectory, id)
sthFile := fmt.Sprintf("%s/%s", dir, opts.sthFile)
if err := os.MkdirAll(dir, os.ModePerm); err != nil {
return fmt.Errorf("%s: %v", log.Description, err)
}
// Fetch next STH
cli, err := client.New(string(log.URL), &http.Client{}, jsonclient.Options{PublicKeyDER: der, UserAgent: opts.HTTPAgent})
if err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
nextSTH, err := cli.GetSTH(ctx)
if err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
nextSTHBytes, err := json.Marshal(nextSTH)
if err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
//
// It's a bit ugly that ct.SignedTreeHead contains fields that
// are not populated. Doesn't cause any prolems here, however.
//
// Bootstrap log if we don't have any STH yet
if _, err := os.Stat(sthFile); err != nil {
if !errors.Is(err, os.ErrNotExist) {
return fmt.Errorf("%s: %v", *log.Description, err)
}
if err := os.WriteFile(sthFile, nextSTHBytes, 0644); err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
logger.Printf("INFO: bootstrapped %s at tree size %d\n", *log.Description, nextSTH.TreeSize)
continue
}
// Otherwise: update an existing STH
currSTHBytes, err := os.ReadFile(sthFile)
if err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
var currSTH ct.SignedTreeHead
if err := json.Unmarshal(currSTHBytes, &currSTH); err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
if nextSTH.TreeSize < currSTH.TreeSize {
return fmt.Errorf("%s: next tree size is smaller: %s", *log.Description, nextSTHBytes)
}
if nextSTH.TreeSize == currSTH.TreeSize {
if !bytes.Equal(nextSTH.SHA256RootHash[:], currSTH.SHA256RootHash[:]) {
return fmt.Errorf("%s: split-view: %s", *log.Description, nextSTHBytes)
}
logger.Printf("INFO: %s is already up-to-date at size %d\n", *log.Description, nextSTH.TreeSize)
continue
}
hashes, err := cli.GetSTHConsistency(ctx, currSTH.TreeSize, nextSTH.TreeSize)
if err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
if err := merkle.VerifyConsistency(currSTH.TreeSize,
nextSTH.TreeSize,
[sha256.Size]byte(currSTH.SHA256RootHash),
[sha256.Size]byte(nextSTH.SHA256RootHash),
proof(hashes)); err != nil {
return fmt.Errorf("%s: inconsistent tree: %v", *log.Description, err)
}
if err := os.WriteFile(sthFile, nextSTHBytes, 0644); err != nil {
return fmt.Errorf("%s: %v", *log.Description, err)
}
logger.Printf("INFO: updated %s to tree size %d\n", *log.Description, nextSTH.TreeSize)
}
return nil
}
// logs select logs that count towards CT-compliance checks. Logs that don't
// have a description are skipped after printing a warning.
func logs(md metadata.Metadata) (logs []metadata.Log) {
for _, operators := range md.Operators {
for _, log := range operators.Logs {
if log.Description == nil {
fmt.Fprintf(os.Stderr, "WARNING: skipping log without description")
continue
}
if log.State == nil {
continue // skip logs with unknown states
}
if log.State.Name == metadata.LogStatePending {
continue // pending logs do not count towards CT-compliance
}
if log.State.Name == metadata.LogStateRetired {
continue // retired logs are not necessarily reachable
}
if log.State.Name == metadata.LogStateRejected {
continue // rejected logs do not count towards CT-compliance
}
logs = append(logs, log)
}
}
return
}
// proof formats hashes so that they can be passed to the merkle package
func proof(hashes [][]byte) (p [][sha256.Size]byte) {
for _, hash := range hashes {
var h [sha256.Size]byte
copy(h[:], hash)
p = append(p, h)
}
return
}
|
