111 lines
3.1 KiB
Go
111 lines
3.1 KiB
Go
|
package fido2
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"encoding/base64"
|
||
|
|
"fmt"
|
||
|
|
"io"
|
||
|
|
"os"
|
||
|
|
"os/exec"
|
||
|
|
"strings"
|
||
|
|
|
||
|
|
"github.com/rfjakob/gocryptfs/internal/cryptocore"
|
||
|
|
"github.com/rfjakob/gocryptfs/internal/exitcodes"
|
||
|
|
"github.com/rfjakob/gocryptfs/internal/tlog"
|
||
|
|
)
|
||
|
|
|
||
|
|
type fidoCommand int
|
||
|
|
|
||
|
|
const (
|
||
|
|
cred fidoCommand = iota
|
||
|
|
assert fidoCommand = iota
|
||
|
|
assertWithPIN fidoCommand = iota
|
||
|
|
)
|
||
|
|
|
||
|
|
const relyingPartyID = "gocryptfs"
|
||
|
|
|
||
|
|
func callFidoCommand(command fidoCommand, device string, stdin []string) ([]string, error) {
|
||
|
|
var cmd *exec.Cmd
|
||
|
|
switch command {
|
||
|
|
case cred:
|
||
|
|
cmd = exec.Command("fido2-cred", "-M", "-h", "-v", device)
|
||
|
|
case assert:
|
||
|
|
cmd = exec.Command("fido2-assert", "-G", "-h", device)
|
||
|
|
case assertWithPIN:
|
||
|
|
cmd = exec.Command("fido2-assert", "-G", "-h", "-v", device)
|
||
|
|
}
|
||
|
|
tlog.Debug.Printf("callFidoCommand: executing %q with args %v", cmd.Path, cmd.Args)
|
||
|
|
cmd.Stderr = os.Stderr
|
||
|
|
in, err := cmd.StdinPipe()
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
for _, s := range stdin {
|
||
|
|
// This does not deadlock because the pipe buffer is big enough (64kiB on Linux)
|
||
|
|
io.WriteString(in, s+"\n")
|
||
|
|
}
|
||
|
|
in.Close()
|
||
|
|
out, err := cmd.Output()
|
||
|
|
if err != nil {
|
||
|
|
return nil, fmt.Errorf("%s failed with %v", cmd.Args[0], err)
|
||
|
|
}
|
||
|
|
return strings.Split(string(out), "\n"), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Register registers a credential using a FIDO2 token
|
||
|
|
func Register(device string, userName string) (credentialID []byte) {
|
||
|
|
tlog.Info.Printf("FIDO2 Register: interact with your device ...")
|
||
|
|
cdh := base64.StdEncoding.EncodeToString(cryptocore.RandBytes(32))
|
||
|
|
userID := base64.StdEncoding.EncodeToString(cryptocore.RandBytes(32))
|
||
|
|
stdin := []string{cdh, relyingPartyID, userName, userID}
|
||
|
|
out, err := callFidoCommand(cred, device, stdin)
|
||
|
|
if err != nil {
|
||
|
|
tlog.Fatal.Println(err)
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
credentialID, err = base64.StdEncoding.DecodeString(out[4])
|
||
|
|
if err != nil {
|
||
|
|
tlog.Fatal.Println(err)
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
return credentialID
|
||
|
|
}
|
||
|
|
|
||
|
|
// Secret generates a HMAC secret using a FIDO2 token
|
||
|
|
func Secret(device string, credentialID []byte, salt []byte) (secret []byte) {
|
||
|
|
tlog.Info.Printf("FIDO2 Secret: interact with your device ...")
|
||
|
|
cdh := base64.StdEncoding.EncodeToString(cryptocore.RandBytes(32))
|
||
|
|
crid := base64.StdEncoding.EncodeToString(credentialID)
|
||
|
|
hmacsalt := base64.StdEncoding.EncodeToString(salt)
|
||
|
|
stdin := []string{cdh, relyingPartyID, crid, hmacsalt}
|
||
|
|
// try asserting without PIN first
|
||
|
|
out, err := callFidoCommand(assert, device, stdin)
|
||
|
|
if err != nil {
|
||
|
|
// if that fails, let's assert with PIN
|
||
|
|
out, err = callFidoCommand(assertWithPIN, device, stdin)
|
||
|
|
if err != nil {
|
||
|
|
tlog.Fatal.Println(err)
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
secret, err = base64.StdEncoding.DecodeString(out[4])
|
||
|
|
if err != nil {
|
||
|
|
tlog.Fatal.Println(err)
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
|
||
|
|
// sanity checks
|
||
|
|
secretLen := len(secret)
|
||
|
|
if secretLen < 32 {
|
||
|
|
tlog.Fatal.Printf("FIDO2 HMACSecret too short (%d)!\n", secretLen)
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
zero := make([]byte, secretLen)
|
||
|
|
if bytes.Equal(zero, secret) {
|
||
|
|
tlog.Fatal.Printf("FIDO2 HMACSecret is all zero!")
|
||
|
|
os.Exit(exitcodes.FIDO2Error)
|
||
|
|
}
|
||
|
|
|
||
|
|
return secret
|
||
|
|
}
|