// Copyright 2017 The go-ethereum Authors // This file is part of the go-ethereum library. // // The go-ethereum library is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // The go-ethereum library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see . // This file contains the implementation for interacting with the Ledger hardware // wallets. The wire protocol spec can be found in the Ledger Blue GitHub repo: // https://raw.githubusercontent.com/LedgerHQ/blue-app-eth/master/doc/ethapp.asc // +build !ios package usbwallet import ( "encoding/binary" "encoding/hex" "errors" "fmt" "io" "math/big" "strconv" "strings" "sync" "time" "github.com/ethereum/go-ethereum/accounts" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/core/types" "github.com/ethereum/go-ethereum/logger" "github.com/ethereum/go-ethereum/logger/glog" "github.com/ethereum/go-ethereum/rlp" "github.com/karalabe/gousb/usb" ) // ledgerDerivationPath is the base derivation parameters used by the wallet. var ledgerDerivationPath = []uint32{0x80000000 + 44, 0x80000000 + 60, 0x80000000 + 0, 0} // ledgerOpcode is an enumeration encoding the supported Ledger opcodes. type ledgerOpcode byte // ledgerParam1 is an enumeration encoding the supported Ledger parameters for // specific opcodes. The same parameter values may be reused between opcodes. type ledgerParam1 byte // ledgerParam2 is an enumeration encoding the supported Ledger parameters for // specific opcodes. The same parameter values may be reused between opcodes. type ledgerParam2 byte const ( ledgerOpRetrieveAddress ledgerOpcode = 0x02 // Returns the public key and Ethereum address for a given BIP 32 path ledgerOpSignTransaction ledgerOpcode = 0x04 // Signs an Ethereum transaction after having the user validate the parameters ledgerOpGetConfiguration ledgerOpcode = 0x06 // Returns specific wallet application configuration ledgerP1DirectlyFetchAddress ledgerParam1 = 0x00 // Return address directly from the wallet ledgerP1ConfirmFetchAddress ledgerParam1 = 0x01 // Require a user confirmation before returning the address ledgerP1InitTransactionData ledgerParam1 = 0x00 // First transaction data block for signing ledgerP1ContTransactionData ledgerParam1 = 0x80 // Subsequent transaction data block for signing ledgerP2DiscardAddressChainCode ledgerParam2 = 0x00 // Do not return the chain code along with the address ledgerP2ReturnAddressChainCode ledgerParam2 = 0x01 // Require a user confirmation before returning the address ) // ledgerWallet represents a live USB Ledger hardware wallet. type ledgerWallet struct { context *usb.Context // USB context to interface libusb through hardwareID deviceID // USB identifiers to identify this device type locationID uint16 // USB bus and address to identify this device instance url *accounts.URL // Textual URL uniquely identifying this wallet device *usb.Device // USB device advertising itself as a Ledger wallet input usb.Endpoint // Input endpoint to send data to this device output usb.Endpoint // Output endpoint to receive data from this device failure error // Any failure that would make the device unusable version [3]byte // Current version of the Ledger Ethereum app (zero if app is offline) accounts []accounts.Account // List of derive accounts pinned on the Ledger paths map[common.Address][]uint32 // Known derivation paths for signing operations quit chan chan error lock sync.RWMutex } // URL implements accounts.Wallet, returning the URL of the Ledger device. func (w *ledgerWallet) URL() accounts.URL { return *w.url } // Status implements accounts.Wallet, always whether the Ledger is opened, closed // or whether the Ethereum app was not started on it. func (w *ledgerWallet) Status() string { w.lock.RLock() defer w.lock.RUnlock() if w.failure != nil { return fmt.Sprintf("Failed: %v", w.failure) } if w.device == nil { return "Closed" } if w.version == [3]byte{0, 0, 0} { return "Ethereum app offline" } return fmt.Sprintf("Ethereum app v%d.%d.%d online", w.version[0], w.version[1], w.version[2]) } // Open implements accounts.Wallet, attempting to open a USB connection to the // Ledger hardware wallet. The Ledger does not require a user passphrase so that // is silently discarded. func (w *ledgerWallet) Open(passphrase string) error { w.lock.Lock() defer w.lock.Unlock() // If the wallet was already opened, don't try to open again if w.device != nil { return accounts.ErrWalletAlreadyOpen } // Otherwise iterate over all USB devices and find this again (no way to directly do this) // Iterate over all attached devices and fetch those seemingly Ledger devices, err := w.context.ListDevices(func(desc *usb.Descriptor) bool { // Only open this single specific device return desc.Vendor == w.hardwareID.Vendor && desc.Product == w.hardwareID.Product && uint16(desc.Bus)<<8+uint16(desc.Address) == w.locationID }) if err != nil { return err } // Device opened, attach to the input and output endpoints device := devices[0] var invalid string switch { case len(device.Descriptor.Configs) == 0: invalid = "no endpoint config available" case len(device.Descriptor.Configs[0].Interfaces) == 0: invalid = "no endpoint interface available" case len(device.Descriptor.Configs[0].Interfaces[0].Setups) == 0: invalid = "no endpoint setup available" case len(device.Descriptor.Configs[0].Interfaces[0].Setups[0].Endpoints) < 2: invalid = "not enough IO endpoints available" } if invalid != "" { device.Close() return fmt.Errorf("ledger wallet [%s] invalid: %s", w.url, invalid) } // Open the input and output endpoints to the device input, err := device.OpenEndpoint( device.Descriptor.Configs[0].Config, device.Descriptor.Configs[0].Interfaces[0].Number, device.Descriptor.Configs[0].Interfaces[0].Setups[0].Number, device.Descriptor.Configs[0].Interfaces[0].Setups[0].Endpoints[1].Address, ) if err != nil { device.Close() return fmt.Errorf("ledger wallet [%s] input open failed: %v", w.url, err) } output, err := device.OpenEndpoint( device.Descriptor.Configs[0].Config, device.Descriptor.Configs[0].Interfaces[0].Number, device.Descriptor.Configs[0].Interfaces[0].Setups[0].Number, device.Descriptor.Configs[0].Interfaces[0].Setups[0].Endpoints[0].Address, ) if err != nil { device.Close() return fmt.Errorf("ledger wallet [%s] output open failed: %v", w.url, err) } // Wallet seems to be successfully opened, guess if the Ethereum app is running w.device, w.input, w.output = device, input, output w.paths = make(map[common.Address][]uint32) w.quit = make(chan chan error) defer func() { go w.heartbeat() }() if _, err := w.deriveAddress(ledgerDerivationPath); err != nil { // Ethereum app is not running, nothing more to do, return return nil } // Try to resolve the Ethereum app's version, will fail prior to v1.0.2 if w.resolveVersion() != nil { w.version = [3]byte{1, 0, 0} // Assume worst case, can't verify if v1.0.0 or v1.0.1 } return nil } // heartbeat is a health check loop for the Ledger wallets to periodically verify // whether they are still present or if they malfunctioned. It is needed because: // - libusb on Windows doesn't support hotplug, so we can't detect USB unplugs // - communication timeout on the Ledger requires a device power cycle to fix func (w *ledgerWallet) heartbeat() { // Execute heartbeat checks until termination or error var ( errc chan error fail error ) for errc == nil && fail == nil { // Wait until termination is requested or the heartbeat cycle arrives select { case errc = <-w.quit: // Termination requested continue case <-time.After(time.Second): // Heartbeat time } // Execute a tiny data exchange to see responsiveness w.lock.Lock() if err := w.resolveVersion(); err == usb.ERROR_IO || err == usb.ERROR_NO_DEVICE { w.failure = err fail = err } w.lock.Unlock() } // In case of error, wait for termination if fail != nil { errc = <-w.quit } errc <- fail } // Close implements accounts.Wallet, closing the USB connection to the Ledger. func (w *ledgerWallet) Close() error { // Terminate the health checks errc := make(chan error) w.quit <- errc herr := <-errc // Save for later, we *must* close the USB // Terminate the device connection w.lock.Lock() defer w.lock.Unlock() if err := w.device.Close(); err != nil { return err } w.device, w.input, w.output, w.paths, w.quit = nil, nil, nil, nil, nil return herr // If all went well, return any health-check errors } // Accounts implements accounts.Wallet, returning the list of accounts pinned to // the Ledger hardware wallet. func (w *ledgerWallet) Accounts() []accounts.Account { w.lock.RLock() defer w.lock.RUnlock() cpy := make([]accounts.Account, len(w.accounts)) copy(cpy, w.accounts) return cpy } // Contains implements accounts.Wallet, returning whether a particular account is // or is not pinned into this Ledger instance. Although we could attempt to resolve // unpinned accounts, that would be an non-negligible hardware operation. func (w *ledgerWallet) Contains(account accounts.Account) bool { w.lock.RLock() defer w.lock.RUnlock() _, exists := w.paths[account.Address] return exists } // Derive implements accounts.Wallet, deriving a new account at the specific // derivation path. If pin is set to true, the account will be added to the list // of tracked accounts. func (w *ledgerWallet) Derive(path string, pin bool) (accounts.Account, error) { w.lock.Lock() defer w.lock.Unlock() // If the wallet is closed, or the Ethereum app doesn't run, abort if w.device == nil || w.version == [3]byte{0, 0, 0} { return accounts.Account{}, accounts.ErrWalletClosed } // All seems fine, convert the user derivation path to Ledger representation path = strings.TrimPrefix(path, "/") parts := strings.Split(path, "/") lpath := make([]uint32, len(parts)) for i, part := range parts { // Handle hardened paths if strings.HasSuffix(part, "'") { lpath[i] = 0x80000000 part = strings.TrimSuffix(part, "'") } // Handle the non hardened component val, err := strconv.Atoi(part) if err != nil { return accounts.Account{}, fmt.Errorf("path element %d: %v", i, err) } lpath[i] += uint32(val) } // Try to derive the actual account and update it's URL if succeeful address, err := w.deriveAddress(lpath) if err != nil { return accounts.Account{}, err } account := accounts.Account{ Address: address, URL: accounts.URL{Scheme: w.url.Scheme, Path: fmt.Sprintf("%s/%s", w.url.Path, path)}, } // If pinning was requested, track the account if pin { if _, ok := w.paths[address]; !ok { w.accounts = append(w.accounts, account) w.paths[address] = lpath } } return account, nil } // SignHash implements accounts.Wallet, however signing arbitrary data is not // supported for Ledger wallets, so this method will always return an error. func (w *ledgerWallet) SignHash(acc accounts.Account, hash []byte) ([]byte, error) { return nil, accounts.ErrNotSupported } // SignTx implements accounts.Wallet. It sends the transaction over to the Ledger // wallet to request a confirmation from the user. It returns either the signed // transaction or a failure if the user denied the transaction. // // Note, if the version of the Ethereum application running on the Ledger wallet is // too old to sign EIP-155 transactions, but such is requested nonetheless, an error // will be returned opposed to silently signing in Homestead mode. func (w *ledgerWallet) SignTx(account accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) { w.lock.Lock() defer w.lock.Unlock() // Make sure the requested account is contained within path, ok := w.paths[account.Address] if !ok { return nil, accounts.ErrUnknownAccount } // Ensure the wallet is capable of signing the given transaction if chainID != nil && w.version[0] <= 1 && w.version[1] <= 0 && w.version[2] <= 2 { return nil, fmt.Errorf("Ledger v%d.%d.%d doesn't support signing this transaction, please update to v1.0.3 at least", w.version[0], w.version[1], w.version[2]) } return w.sign(path, account.Address, tx, chainID) } // SignHashWithPassphrase implements accounts.Wallet, however signing arbitrary // data is not supported for Ledger wallets, so this method will always return // an error. func (w *ledgerWallet) SignHashWithPassphrase(account accounts.Account, passphrase string, hash []byte) ([]byte, error) { return nil, accounts.ErrNotSupported } // SignTxWithPassphrase implements accounts.Wallet, attempting to sign the given // transaction with the given account using passphrase as extra authentication. // Since the Ledger does not support extra passphrases, it is silently ignored. func (w *ledgerWallet) SignTxWithPassphrase(account accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) { return w.SignTx(account, tx, chainID) } // resolveVersion retrieves the current version of the Ethereum wallet app running // on the Ledger wallet and caches it for future reference. // // The version retrieval protocol is defined as follows: // // CLA | INS | P1 | P2 | Lc | Le // ----+-----+----+----+----+--- // E0 | 06 | 00 | 00 | 00 | 04 // // With no input data, and the output data being: // // Description | Length // ---------------------------------------------------+-------- // Flags 01: arbitrary data signature enabled by user | 1 byte // Application major version | 1 byte // Application minor version | 1 byte // Application patch version | 1 byte func (wallet *ledgerWallet) resolveVersion() error { // Send the request and wait for the response reply, err := wallet.exchange(ledgerOpGetConfiguration, 0, 0, nil) if err != nil { return err } if len(reply) != 4 { return errors.New("reply not of correct size") } // Cache the version for future reference copy(wallet.version[:], reply[1:]) return nil } // deriveAddress retrieves the currently active Ethereum address from a Ledger // wallet at the specified derivation path. // // The address derivation protocol is defined as follows: // // CLA | INS | P1 | P2 | Lc | Le // ----+-----+----+----+-----+--- // E0 | 02 | 00 return address // 01 display address and confirm before returning // | 00: do not return the chain code // | 01: return the chain code // | var | 00 // // Where the input data is: // // Description | Length // -------------------------------------------------+-------- // Number of BIP 32 derivations to perform (max 10) | 1 byte // First derivation index (big endian) | 4 bytes // ... | 4 bytes // Last derivation index (big endian) | 4 bytes // // And the output data is: // // Description | Length // ------------------------+------------------- // Public Key length | 1 byte // Uncompressed Public Key | arbitrary // Ethereum address length | 1 byte // Ethereum address | 40 bytes hex ascii // Chain code if requested | 32 bytes func (w *ledgerWallet) deriveAddress(derivationPath []uint32) (common.Address, error) { // Flatten the derivation path into the Ledger request path := make([]byte, 1+4*len(derivationPath)) path[0] = byte(len(derivationPath)) for i, component := range derivationPath { binary.BigEndian.PutUint32(path[1+4*i:], component) } // Send the request and wait for the response reply, err := w.exchange(ledgerOpRetrieveAddress, ledgerP1DirectlyFetchAddress, ledgerP2DiscardAddressChainCode, path) if err != nil { return common.Address{}, err } // Discard the public key, we don't need that for now if len(reply) < 1 || len(reply) < 1+int(reply[0]) { return common.Address{}, errors.New("reply lacks public key entry") } reply = reply[1+int(reply[0]):] // Extract the Ethereum hex address string if len(reply) < 1 || len(reply) < 1+int(reply[0]) { return common.Address{}, errors.New("reply lacks address entry") } hexstr := reply[1 : 1+int(reply[0])] // Decode the hex sting into an Ethereum address and return var address common.Address hex.Decode(address[:], hexstr) return address, nil } // sign sends the transaction to the Ledger wallet, and waits for the user to // confirm or deny the transaction. // // The transaction signing protocol is defined as follows: // // CLA | INS | P1 | P2 | Lc | Le // ----+-----+----+----+-----+--- // E0 | 04 | 00: first transaction data block // 80: subsequent transaction data block // | 00 | variable | variable // // Where the input for the first transaction block (first 255 bytes) is: // // Description | Length // -------------------------------------------------+---------- // Number of BIP 32 derivations to perform (max 10) | 1 byte // First derivation index (big endian) | 4 bytes // ... | 4 bytes // Last derivation index (big endian) | 4 bytes // RLP transaction chunk | arbitrary // // And the input for subsequent transaction blocks (first 255 bytes) are: // // Description | Length // ----------------------+---------- // RLP transaction chunk | arbitrary // // And the output data is: // // Description | Length // ------------+--------- // signature V | 1 byte // signature R | 32 bytes // signature S | 32 bytes func (w *ledgerWallet) sign(derivationPath []uint32, address common.Address, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) { // We need to modify the timeouts to account for user feedback defer func(old time.Duration) { w.device.ReadTimeout = old }(w.device.ReadTimeout) w.device.ReadTimeout = time.Minute // Flatten the derivation path into the Ledger request path := make([]byte, 1+4*len(derivationPath)) path[0] = byte(len(derivationPath)) for i, component := range derivationPath { binary.BigEndian.PutUint32(path[1+4*i:], component) } // Create the transaction RLP based on whether legacy or EIP155 signing was requeste var ( txrlp []byte err error ) if chainID == nil { if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data()}); err != nil { return nil, err } } else { if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data(), chainID, big.NewInt(0), big.NewInt(0)}); err != nil { return nil, err } } payload := append(path, txrlp...) // Send the request and wait for the response var ( op = ledgerP1InitTransactionData reply []byte ) for len(payload) > 0 { // Calculate the size of the next data chunk chunk := 255 if chunk > len(payload) { chunk = len(payload) } // Send the chunk over, ensuring it's processed correctly reply, err = w.exchange(ledgerOpSignTransaction, op, 0, payload[:chunk]) if err != nil { return nil, err } // Shift the payload and ensure subsequent chunks are marked as such payload = payload[chunk:] op = ledgerP1ContTransactionData } // Extract the Ethereum signature and do a sanity validation if len(reply) != 65 { return nil, errors.New("reply lacks signature") } signature := append(reply[1:], reply[0]) // Create the correct signer and signature transform based on the chain ID var signer types.Signer if chainID == nil { signer = new(types.HomesteadSigner) } else { signer = types.NewEIP155Signer(chainID) signature[64] = (signature[64]-34)/2 - byte(chainID.Uint64()) } // Inject the final signature into the transaction and sanity check the sender signed, err := tx.WithSignature(signer, signature) if err != nil { return nil, err } sender, err := types.Sender(signer, signed) if err != nil { return nil, err } if sender != address { return nil, fmt.Errorf("signer mismatch: expected %s, got %s", address.Hex(), sender.Hex()) } return signed, nil } // exchange performs a data exchange with the Ledger wallet, sending it a message // and retrieving the response. // // The common transport header is defined as follows: // // Description | Length // --------------------------------------+---------- // Communication channel ID (big endian) | 2 bytes // Command tag | 1 byte // Packet sequence index (big endian) | 2 bytes // Payload | arbitrary // // The Communication channel ID allows commands multiplexing over the same // physical link. It is not used for the time being, and should be set to 0101 // to avoid compatibility issues with implementations ignoring a leading 00 byte. // // The Command tag describes the message content. Use TAG_APDU (0x05) for standard // APDU payloads, or TAG_PING (0x02) for a simple link test. // // The Packet sequence index describes the current sequence for fragmented payloads. // The first fragment index is 0x00. // // APDU Command payloads are encoded as follows: // // Description | Length // ----------------------------------- // APDU length (big endian) | 2 bytes // APDU CLA | 1 byte // APDU INS | 1 byte // APDU P1 | 1 byte // APDU P2 | 1 byte // APDU length | 1 byte // Optional APDU data | arbitrary func (w *ledgerWallet) exchange(opcode ledgerOpcode, p1 ledgerParam1, p2 ledgerParam2, data []byte) ([]byte, error) { // Construct the message payload, possibly split into multiple chunks var chunks [][]byte for left := data; len(left) > 0 || len(chunks) == 0; { // Create the chunk header var chunk []byte if len(chunks) == 0 { // The first chunk encodes the length and all the opcodes chunk = []byte{0x00, 0x00, 0xe0, byte(opcode), byte(p1), byte(p2), byte(len(data))} binary.BigEndian.PutUint16(chunk, uint16(5+len(data))) } // Append the data blob to the end of the chunk space := 64 - len(chunk) - 5 // 5 == header size if len(left) > space { chunks, left = append(chunks, append(chunk, left[:space]...)), left[space:] continue } chunks, left = append(chunks, append(chunk, left...)), nil } // Stream all the chunks to the device for i, chunk := range chunks { // Construct the new message to stream header := []byte{0x01, 0x01, 0x05, 0x00, 0x00} // Channel ID and command tag appended binary.BigEndian.PutUint16(header[3:], uint16(i)) msg := append(header, chunk...) // Send over to the device if glog.V(logger.Core) { glog.Infof("-> %03d.%03d: %x", w.device.Bus, w.device.Address, msg) } if _, err := w.input.Write(msg); err != nil { return nil, err } } // Stream the reply back from the wallet in 64 byte chunks var reply []byte for { // Read the next chunk from the Ledger wallet chunk := make([]byte, 64) if _, err := io.ReadFull(w.output, chunk); err != nil { return nil, err } if glog.V(logger.Core) { glog.Infof("<- %03d.%03d: %x", w.device.Bus, w.device.Address, chunk) } // Make sure the transport header matches if chunk[0] != 0x01 || chunk[1] != 0x01 || chunk[2] != 0x05 { return nil, fmt.Errorf("invalid reply header: %x", chunk[:3]) } // If it's the first chunk, retrieve the total message length if chunk[3] == 0x00 && chunk[4] == 0x00 { reply = make([]byte, 0, int(binary.BigEndian.Uint16(chunk[5:7]))) chunk = chunk[7:] } else { chunk = chunk[5:] } // Append to the reply and stop when filled up if left := cap(reply) - len(reply); left > len(chunk) { reply = append(reply, chunk...) } else { reply = append(reply, chunk[:left]...) break } } return reply[:len(reply)-2], nil }