verify.go

   1 /*
   2 Copyright (C) 2021 Sergey Matveev <stargrave@stargrave.org>
   3
   4 This program is free software: you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation, version 3 of the License.
   7
   8 This program is distributed in the hope that it will be useful,
   9 but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 GNU General Public License for more details.
  12
  13 You should have received a copy of the GNU General Public License
  14 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16
  17 package main
  18
  19 import (
  20         "bytes"
  21         "crypto/x509"
  22         "encoding/pem"
  23         "fmt"
  24         "io/ioutil"
  25         "log"
  26         "os"
  27         "os/exec"
  28         "path/filepath"
  29         "strings"
  30
  31         "go.cypherpunks.ru/ucspi"
  32 )
  33
  34 func certInfo(certRaw []byte) string {
  35         cmd := exec.Command("certtool", "--certificate-info", "--inder")
  36         cmd.Stdin = bytes.NewReader(certRaw)
  37         out, err := cmd.Output()
  38         if err != nil {
  39                 return err.Error()
  40         }
  41         lines := make([]string, 0, 128)
  42         for i, line := range strings.Split(string(out), "\n") {
  43                 if strings.Contains(line, "ASCII:") {
  44                         continue
  45                 }
  46                 lines = append(lines, fmt.Sprintf(
  47                         "%03d %s", i, strings.ReplaceAll(line, `"`, `\"`),
  48                 ))
  49         }
  50         return strings.Join(lines, "\n")
  51 }
  52
  53 func verifyCert(
  54         host string,
  55         dialErr error,
  56         rawCerts [][]byte,
  57         verifiedChains [][]*x509.Certificate,
  58 ) error {
  59         var certTheir *x509.Certificate
  60         var err error
  61         if len(verifiedChains) > 0 {
  62                 certTheir = verifiedChains[0][0]
  63         } else {
  64                 certTheir, err = x509.ParseCertificate(rawCerts[0])
  65                 if err != nil {
  66                         return err
  67                 }
  68         }
  69         certTheirHash := spkiHash(certTheir)
  70         acceptedM.RLock()
  71         certOurHash := accepted[host]
  72         acceptedM.RUnlock()
  73         if certTheirHash == certOurHash {
  74                 return nil
  75         }
  76         rejectedM.RLock()
  77         certOurHash = rejected[host]
  78         rejectedM.RUnlock()
  79         if certTheirHash == certOurHash {
  80                 return ErrRejected{host}
  81         }
  82         daneExists, daneMatched := dane(host, certTheir)
  83         if daneExists {
  84                 if daneMatched {
  85                         sinkCert <- fmt.Sprintf("DANE\t%s\tmatched", host)
  86                 } else {
  87                         sinkErr <- fmt.Sprintf("DANE\t%s\tnot matched", host)
  88                 }
  89         }
  90         fn := filepath.Join(*certs, host)
  91         certsOur, _, err := ucspi.CertPoolFromFile(fn)
  92         if err == nil || dialErr != nil || (daneExists && !daneMatched) {
  93                 if certsOur != nil && certTheirHash == spkiHash(certsOur[0]) {
  94                         acceptedAdd(host, certTheirHash)
  95                         if bytes.Compare(certsOur[0].Raw, rawCerts[0]) != 0 {
  96                                 sinkCert <- fmt.Sprintf("Refresh\t%s\t%s", host, certTheirHash)
  97                                 goto CertUpdate
  98                         }
  99                         return nil
 100                 }
 101                 var b bytes.Buffer
 102                 b.WriteString(fmt.Sprintf("wm title . \"%s\"\n", host))
 103
 104                 if dialErr != nil {
 105                         b.WriteString(fmt.Sprintf(`set tErr [text .tErr]
 106 $tErr insert end "%s"
 107 $tErr configure -wrap word -height 5
 108 `, dialErr.Error()))
 109                         b.WriteString("grid .tErr -columnspan 3\n")
 110                 }
 111
 112                 if daneExists {
 113                         if daneMatched {
 114                                 b.WriteString("label .lDANE -bg green -text \"DANE matched\"\n")
 115                         } else {
 116                                 b.WriteString("label .lDANE -bg red -text \"DANE not matched!\"\n")
 117                         }
 118                         b.WriteString("grid .lDANE\n")
 119                 }
 120
 121                 var bCerts bytes.Buffer
 122                 for i, rawCert := range rawCerts {
 123                         bCerts.WriteString(fmt.Sprintf("Their %d:\n", i))
 124                         bCerts.WriteString(certInfo(rawCert))
 125                 }
 126                 b.WriteString(fmt.Sprintf(`set tTheir [text .tTheir]
 127 $tTheir insert end "%s"
 128 set sbTheir [scrollbar .sbTheir -command [list $tTheir yview]]
 129 $tTheir configure -wrap word -yscrollcommand [list $sbTheir set]
 130 `, bCerts.String()))
 131                 b.WriteString("grid $tTheir $sbTheir -sticky nsew -columnspan 3\n")
 132
 133                 if certsOur != nil {
 134                         bCerts.Reset()
 135                         for i, cert := range certsOur {
 136                                 bCerts.WriteString(fmt.Sprintf("Our %d:\n", i))
 137                                 bCerts.WriteString(certInfo(cert.Raw))
 138                         }
 139                         b.WriteString(fmt.Sprintf(`set tOur [text .tOur]
 140 $tOur insert end "%s"
 141 set sbOur [scrollbar .sbOur -command [list $tOur yview]]
 142 $tOur configure -wrap word -yscrollcommand [list $sbOur set]
 143 `, bCerts.String()))
 144                         b.WriteString("grid $tOur $sbOur -sticky nsew -columnspan 3\n")
 145                 }
 146
 147                 b.WriteString(`
 148 proc doAccept {} { exit 10 }
 149 proc doOnce {} { exit 11 }
 150 proc doReject {} { exit 12 }
 151 button .bAccept -text "Accept" -bg green -command doAccept
 152 button .bOnce -text "Once" -command doOnce
 153 button .bReject -text "Reject" -bg red -command doReject
 154 grid .bAccept .bOnce .bReject
 155 grid rowconfigure . 0 -weight 1
 156 grid columnconfigure . 0 -weight 1
 157 `)
 158
 159                 cmd := exec.Command("wish8.7")
 160                 ioutil.WriteFile("/tmp/w.tcl", b.Bytes(), 0666)
 161                 cmd.Stdin = &b
 162                 err = cmd.Run()
 163                 exitError, ok := err.(*exec.ExitError)
 164                 if !ok {
 165                         sinkCert <- fmt.Sprintf("DENY\t%s\t%s", host, certTheirHash)
 166                         return ErrRejected{host}
 167                 }
 168                 switch exitError.ExitCode() {
 169                 case 10:
 170                         sinkCert <- fmt.Sprintf("ADD\t%s\t%s", host, certTheirHash)
 171                         goto CertUpdate
 172                 case 11:
 173                         sinkCert <- fmt.Sprintf("ONCE\t%s\t%s", host, certTheirHash)
 174                         acceptedAdd(host, certTheirHash)
 175                         return nil
 176                 case 12:
 177                         rejectedAdd(host, certTheirHash)
 178                         fallthrough
 179                 default:
 180                         sinkCert <- fmt.Sprintf("DENY\t%s\t%s", host, certTheirHash)
 181                         return ErrRejected{host}
 182                 }
 183         } else {
 184                 if !os.IsNotExist(err) {
 185                         return err
 186                 }
 187                 sinkCert <- fmt.Sprintf("TOFU\t%s\t%s", host, certTheirHash)
 188         }
 189 CertUpdate:
 190         tmp, err := os.CreateTemp(*certs, "")
 191         if err != nil {
 192                 log.Fatalln(err)
 193         }
 194         for _, rawCert := range rawCerts {
 195                 err = pem.Encode(tmp, &pem.Block{Type: "CERTIFICATE", Bytes: rawCert})
 196                 if err != nil {
 197                         log.Fatalln(err)
 198                 }
 199         }
 200         tmp.Close()
 201         os.Rename(tmp.Name(), fn)
 202         acceptedAdd(host, certTheirHash)
 203         return nil
 204 }