mirror of
https://github.com/woodpecker-ci/woodpecker.git
synced 2024-11-30 22:01:01 +00:00
352 lines
8.9 KiB
Go
352 lines
8.9 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package ssh
|
|
|
|
import (
|
|
"crypto"
|
|
"fmt"
|
|
"sync"
|
|
|
|
_ "crypto/sha1"
|
|
_ "crypto/sha256"
|
|
_ "crypto/sha512"
|
|
)
|
|
|
|
// These are string constants in the SSH protocol.
|
|
const (
|
|
compressionNone = "none"
|
|
serviceUserAuth = "ssh-userauth"
|
|
serviceSSH = "ssh-connection"
|
|
)
|
|
|
|
var supportedKexAlgos = []string{
|
|
kexAlgoECDH256, kexAlgoECDH384, kexAlgoECDH521,
|
|
kexAlgoDH14SHA1, kexAlgoDH1SHA1,
|
|
}
|
|
|
|
var supportedHostKeyAlgos = []string{
|
|
KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
|
|
KeyAlgoRSA, KeyAlgoDSA,
|
|
}
|
|
|
|
var supportedCompressions = []string{compressionNone}
|
|
|
|
// hashFuncs keeps the mapping of supported algorithms to their respective
|
|
// hashes needed for signature verification.
|
|
var hashFuncs = map[string]crypto.Hash{
|
|
KeyAlgoRSA: crypto.SHA1,
|
|
KeyAlgoDSA: crypto.SHA1,
|
|
KeyAlgoECDSA256: crypto.SHA256,
|
|
KeyAlgoECDSA384: crypto.SHA384,
|
|
KeyAlgoECDSA521: crypto.SHA512,
|
|
CertAlgoRSAv01: crypto.SHA1,
|
|
CertAlgoDSAv01: crypto.SHA1,
|
|
CertAlgoECDSA256v01: crypto.SHA256,
|
|
CertAlgoECDSA384v01: crypto.SHA384,
|
|
CertAlgoECDSA521v01: crypto.SHA512,
|
|
}
|
|
|
|
// UnexpectedMessageError results when the SSH message that we received didn't
|
|
// match what we wanted.
|
|
type UnexpectedMessageError struct {
|
|
expected, got uint8
|
|
}
|
|
|
|
func (u UnexpectedMessageError) Error() string {
|
|
return fmt.Sprintf("ssh: unexpected message type %d (expected %d)", u.got, u.expected)
|
|
}
|
|
|
|
// ParseError results from a malformed SSH message.
|
|
type ParseError struct {
|
|
msgType uint8
|
|
}
|
|
|
|
func (p ParseError) Error() string {
|
|
return fmt.Sprintf("ssh: parse error in message type %d", p.msgType)
|
|
}
|
|
|
|
func findCommonAlgorithm(clientAlgos []string, serverAlgos []string) (commonAlgo string, ok bool) {
|
|
for _, clientAlgo := range clientAlgos {
|
|
for _, serverAlgo := range serverAlgos {
|
|
if clientAlgo == serverAlgo {
|
|
return clientAlgo, true
|
|
}
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func findCommonCipher(clientCiphers []string, serverCiphers []string) (commonCipher string, ok bool) {
|
|
for _, clientCipher := range clientCiphers {
|
|
for _, serverCipher := range serverCiphers {
|
|
// reject the cipher if we have no cipherModes definition
|
|
if clientCipher == serverCipher && cipherModes[clientCipher] != nil {
|
|
return clientCipher, true
|
|
}
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
type algorithms struct {
|
|
kex string
|
|
hostKey string
|
|
wCipher string
|
|
rCipher string
|
|
rMAC string
|
|
wMAC string
|
|
rCompression string
|
|
wCompression string
|
|
}
|
|
|
|
func findAgreedAlgorithms(clientKexInit, serverKexInit *kexInitMsg) (algs *algorithms) {
|
|
var ok bool
|
|
result := &algorithms{}
|
|
result.kex, ok = findCommonAlgorithm(clientKexInit.KexAlgos, serverKexInit.KexAlgos)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.hostKey, ok = findCommonAlgorithm(clientKexInit.ServerHostKeyAlgos, serverKexInit.ServerHostKeyAlgos)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.wCipher, ok = findCommonCipher(clientKexInit.CiphersClientServer, serverKexInit.CiphersClientServer)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.rCipher, ok = findCommonCipher(clientKexInit.CiphersServerClient, serverKexInit.CiphersServerClient)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.wMAC, ok = findCommonAlgorithm(clientKexInit.MACsClientServer, serverKexInit.MACsClientServer)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.rMAC, ok = findCommonAlgorithm(clientKexInit.MACsServerClient, serverKexInit.MACsServerClient)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.wCompression, ok = findCommonAlgorithm(clientKexInit.CompressionClientServer, serverKexInit.CompressionClientServer)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
result.rCompression, ok = findCommonAlgorithm(clientKexInit.CompressionServerClient, serverKexInit.CompressionServerClient)
|
|
if !ok {
|
|
return
|
|
}
|
|
|
|
return result
|
|
}
|
|
|
|
// Cryptographic configuration common to both ServerConfig and ClientConfig.
|
|
type CryptoConfig struct {
|
|
// The allowed key exchanges algorithms. If unspecified then a
|
|
// default set of algorithms is used.
|
|
KeyExchanges []string
|
|
|
|
// The allowed cipher algorithms. If unspecified then DefaultCipherOrder is
|
|
// used.
|
|
Ciphers []string
|
|
|
|
// The allowed MAC algorithms. If unspecified then DefaultMACOrder is used.
|
|
MACs []string
|
|
}
|
|
|
|
func (c *CryptoConfig) ciphers() []string {
|
|
if c.Ciphers == nil {
|
|
return DefaultCipherOrder
|
|
}
|
|
return c.Ciphers
|
|
}
|
|
|
|
func (c *CryptoConfig) kexes() []string {
|
|
if c.KeyExchanges == nil {
|
|
return defaultKeyExchangeOrder
|
|
}
|
|
return c.KeyExchanges
|
|
}
|
|
|
|
func (c *CryptoConfig) macs() []string {
|
|
if c.MACs == nil {
|
|
return DefaultMACOrder
|
|
}
|
|
return c.MACs
|
|
}
|
|
|
|
// serialize a signed slice according to RFC 4254 6.6. The name should
|
|
// be a key type name, rather than a cert type name.
|
|
func serializeSignature(name string, sig []byte) []byte {
|
|
length := stringLength(len(name))
|
|
length += stringLength(len(sig))
|
|
|
|
ret := make([]byte, length)
|
|
r := marshalString(ret, []byte(name))
|
|
r = marshalString(r, sig)
|
|
|
|
return ret
|
|
}
|
|
|
|
// MarshalPublicKey serializes a supported key or certificate for use
|
|
// by the SSH wire protocol. It can be used for comparison with the
|
|
// pubkey argument of ServerConfig's PublicKeyCallback as well as for
|
|
// generating an authorized_keys or host_keys file.
|
|
func MarshalPublicKey(key PublicKey) []byte {
|
|
// See also RFC 4253 6.6.
|
|
algoname := key.PublicKeyAlgo()
|
|
blob := key.Marshal()
|
|
|
|
length := stringLength(len(algoname))
|
|
length += len(blob)
|
|
ret := make([]byte, length)
|
|
r := marshalString(ret, []byte(algoname))
|
|
copy(r, blob)
|
|
return ret
|
|
}
|
|
|
|
// pubAlgoToPrivAlgo returns the private key algorithm format name that
|
|
// corresponds to a given public key algorithm format name. For most
|
|
// public keys, the private key algorithm name is the same. For some
|
|
// situations, such as openssh certificates, the private key algorithm and
|
|
// public key algorithm names differ. This accounts for those situations.
|
|
func pubAlgoToPrivAlgo(pubAlgo string) string {
|
|
switch pubAlgo {
|
|
case CertAlgoRSAv01:
|
|
return KeyAlgoRSA
|
|
case CertAlgoDSAv01:
|
|
return KeyAlgoDSA
|
|
case CertAlgoECDSA256v01:
|
|
return KeyAlgoECDSA256
|
|
case CertAlgoECDSA384v01:
|
|
return KeyAlgoECDSA384
|
|
case CertAlgoECDSA521v01:
|
|
return KeyAlgoECDSA521
|
|
}
|
|
return pubAlgo
|
|
}
|
|
|
|
// buildDataSignedForAuth returns the data that is signed in order to prove
|
|
// possession of a private key. See RFC 4252, section 7.
|
|
func buildDataSignedForAuth(sessionId []byte, req userAuthRequestMsg, algo, pubKey []byte) []byte {
|
|
user := []byte(req.User)
|
|
service := []byte(req.Service)
|
|
method := []byte(req.Method)
|
|
|
|
length := stringLength(len(sessionId))
|
|
length += 1
|
|
length += stringLength(len(user))
|
|
length += stringLength(len(service))
|
|
length += stringLength(len(method))
|
|
length += 1
|
|
length += stringLength(len(algo))
|
|
length += stringLength(len(pubKey))
|
|
|
|
ret := make([]byte, length)
|
|
r := marshalString(ret, sessionId)
|
|
r[0] = msgUserAuthRequest
|
|
r = r[1:]
|
|
r = marshalString(r, user)
|
|
r = marshalString(r, service)
|
|
r = marshalString(r, method)
|
|
r[0] = 1
|
|
r = r[1:]
|
|
r = marshalString(r, algo)
|
|
r = marshalString(r, pubKey)
|
|
return ret
|
|
}
|
|
|
|
// safeString sanitises s according to RFC 4251, section 9.2.
|
|
// All control characters except tab, carriage return and newline are
|
|
// replaced by 0x20.
|
|
func safeString(s string) string {
|
|
out := []byte(s)
|
|
for i, c := range out {
|
|
if c < 0x20 && c != 0xd && c != 0xa && c != 0x9 {
|
|
out[i] = 0x20
|
|
}
|
|
}
|
|
return string(out)
|
|
}
|
|
|
|
func appendU16(buf []byte, n uint16) []byte {
|
|
return append(buf, byte(n>>8), byte(n))
|
|
}
|
|
|
|
func appendU32(buf []byte, n uint32) []byte {
|
|
return append(buf, byte(n>>24), byte(n>>16), byte(n>>8), byte(n))
|
|
}
|
|
|
|
func appendInt(buf []byte, n int) []byte {
|
|
return appendU32(buf, uint32(n))
|
|
}
|
|
|
|
func appendString(buf []byte, s string) []byte {
|
|
buf = appendU32(buf, uint32(len(s)))
|
|
buf = append(buf, s...)
|
|
return buf
|
|
}
|
|
|
|
func appendBool(buf []byte, b bool) []byte {
|
|
if b {
|
|
buf = append(buf, 1)
|
|
} else {
|
|
buf = append(buf, 0)
|
|
}
|
|
return buf
|
|
}
|
|
|
|
// newCond is a helper to hide the fact that there is no usable zero
|
|
// value for sync.Cond.
|
|
func newCond() *sync.Cond { return sync.NewCond(new(sync.Mutex)) }
|
|
|
|
// window represents the buffer available to clients
|
|
// wishing to write to a channel.
|
|
type window struct {
|
|
*sync.Cond
|
|
win uint32 // RFC 4254 5.2 says the window size can grow to 2^32-1
|
|
}
|
|
|
|
// add adds win to the amount of window available
|
|
// for consumers.
|
|
func (w *window) add(win uint32) bool {
|
|
// a zero sized window adjust is a noop.
|
|
if win == 0 {
|
|
return true
|
|
}
|
|
w.L.Lock()
|
|
if w.win+win < win {
|
|
w.L.Unlock()
|
|
return false
|
|
}
|
|
w.win += win
|
|
// It is unusual that multiple goroutines would be attempting to reserve
|
|
// window space, but not guaranteed. Use broadcast to notify all waiters
|
|
// that additional window is available.
|
|
w.Broadcast()
|
|
w.L.Unlock()
|
|
return true
|
|
}
|
|
|
|
// reserve reserves win from the available window capacity.
|
|
// If no capacity remains, reserve will block. reserve may
|
|
// return less than requested.
|
|
func (w *window) reserve(win uint32) uint32 {
|
|
w.L.Lock()
|
|
for w.win == 0 {
|
|
w.Wait()
|
|
}
|
|
if w.win < win {
|
|
win = w.win
|
|
}
|
|
w.win -= win
|
|
w.L.Unlock()
|
|
return win
|
|
}
|