func (k KnownHosts) HostKeyCallback(hostname string, remote net.Addr, key ssh.PublicKey) error {
var addr *net.TCPAddr
if v, ok := remote.(*net.TCPAddr); ok {
addr = v
} else {
return UnsupportedAddrType
}
keyBytes := key.Marshal()
var matched []*Host
for _, l := range k {
if l.CertAuthority {
continue
}
if key.Type() != l.PublicKey.Type() {
continue
}
lKeyBytes := l.PublicKey.Marshal()
for _, h := range l.Hosts {
if h.Match(hostname, addr) {
if !bytes.Equal(keyBytes, lKeyBytes) {
return HostKeyMismatchError
}
if l.Revoked {
return HostRevokedError
}
matched = append(matched, h)
}
}
}
if len(matched) == 0 {
return HostNotFoundError
}
return nil
}
// compareKeys compares to key files and returns true of they match.
func compareKeys(a, b ssh.PublicKey) bool {
if a.Type() != b.Type() {
return false
}
// The best way to compare just the key seems to be to marshal both and
// then compare the output byte sequence.
return subtle.ConstantTimeCompare(a.Marshal(), b.Marshal()) == 1
}
func (k *storedHostKey) Check(addr string, remote net.Addr, key ssh.PublicKey) error {
k.checkCount++
algo := key.Type()
if k.keys == nil || bytes.Compare(key.Marshal(), k.keys[algo]) != 0 {
return fmt.Errorf("host key mismatch. Got %q, want %q", key, k.keys[algo])
}
return nil
}
/* logPubKey logs a public key attempt */
func logPubKey(
conn ssh.ConnMetadata,
key ssh.PublicKey,
) (*ssh.Permissions, error) {
log.Printf(
"%v Key(%v):%02X",
ci(conn),
key.Type(),
md5.Sum(key.Marshal()),
)
return nil, fmt.Errorf("invalid key")
}
func testAgentInterface(t *testing.T, agent Agent, key interface{}, cert *ssh.Certificate, lifetimeSecs uint32) {
signer, err := ssh.NewSignerFromKey(key)
if err != nil {
t.Fatalf("NewSignerFromKey(%T): %v", key, err)
}
// The agent should start up empty.
if keys, err := agent.List(); err != nil {
t.Fatalf("RequestIdentities: %v", err)
} else if len(keys) > 0 {
t.Fatalf("got %d keys, want 0: %v", len(keys), keys)
}
// Attempt to insert the key, with certificate if specified.
var pubKey ssh.PublicKey
if cert != nil {
err = agent.Add(AddedKey{
PrivateKey: key,
Certificate: cert,
Comment: "comment",
LifetimeSecs: lifetimeSecs,
})
pubKey = cert
} else {
err = agent.Add(AddedKey{PrivateKey: key, Comment: "comment", LifetimeSecs: lifetimeSecs})
pubKey = signer.PublicKey()
}
if err != nil {
t.Fatalf("insert(%T): %v", key, err)
}
// Did the key get inserted successfully?
if keys, err := agent.List(); err != nil {
t.Fatalf("List: %v", err)
} else if len(keys) != 1 {
t.Fatalf("got %v, want 1 key", keys)
} else if keys[0].Comment != "comment" {
t.Fatalf("key comment: got %v, want %v", keys[0].Comment, "comment")
} else if !bytes.Equal(keys[0].Blob, pubKey.Marshal()) {
t.Fatalf("key mismatch")
}
// Can the agent make a valid signature?
data := []byte("hello")
sig, err := agent.Sign(pubKey, data)
if err != nil {
t.Fatalf("Sign(%s): %v", pubKey.Type(), err)
}
if err := pubKey.Verify(data, sig); err != nil {
t.Fatalf("Verify(%s): %v", pubKey.Type(), err)
}
}
func sshToCrypto(pk ssh.PublicKey) crypto.PublicKey {
// Don't judge me, judge the ssh.PublicKey interface. And me. A bit.
switch pk.Type() {
case ssh.KeyAlgoRSA:
return (*rsa.PublicKey)(unsafe.Pointer(reflect.ValueOf(pk).Elem().UnsafeAddr()))
case ssh.KeyAlgoDSA:
return (*dsa.PublicKey)(unsafe.Pointer(reflect.ValueOf(pk).Elem().UnsafeAddr()))
case ssh.KeyAlgoECDSA256, ssh.KeyAlgoECDSA384, ssh.KeyAlgoECDSA521:
return (*ecdsa.PublicKey)(unsafe.Pointer(reflect.ValueOf(pk).Elem().UnsafeAddr()))
default:
return nil
}
}
// authKey records any incoming request trying to auth with an ssh key
func authKey(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
h := sha256.New()
h.Write(key.Marshal())
sum := h.Sum(nil)
log.Printf("sshkey: %s %s %s %s\n",
conn.RemoteAddr().String(),
conn.User(),
key.Type(),
base64.StdEncoding.EncodeToString(sum))
return nil, errAuthenticationFailed
}
// Check is called during the handshake to check the server's public key for
// unexpected changes. The key argument is in SSH wire format. It can be parsed
// using ssh.ParsePublicKey. The address before DNS resolution is passed in the
// addr argument, so the key can also be checked against the hostname.
// It returns any error encountered while checking the public key. A nil return
// value indicates that the key was either successfully verified (against an
// existing known_hosts entry), or accepted by the user as a new key.
func (kc *HostKeyChecker) Check(addr string, remote net.Addr, key gossh.PublicKey) error {
remoteAddr, err := kc.addrToHostPort(remote.String())
if err != nil {
return err
}
algoStr := algoString(key.Type())
keyFingerprintStr := md5String(md5.Sum(key.Marshal()))
hostKeys, err := kc.m.GetHostKeys()
_, ok := err.(*os.PathError)
if err != nil && !ok {
log.Errorf("Failed to read known_hosts file %v: %v", kc.m.String(), err)
}
mismatched := false
for pattern, keys := range hostKeys {
if !matchHost(remoteAddr, pattern) {
continue
}
for _, hostKey := range keys {
// Any matching key is considered a success, irrespective of previous failures
if hostKey.Type() == key.Type() && bytes.Compare(hostKey.Marshal(), key.Marshal()) == 0 {
return nil
}
// TODO(jonboulle): could be super friendly like the OpenSSH client
// and note exactly which key failed (file + line number)
mismatched = true
}
}
if mismatched {
fmt.Fprintf(os.Stderr, warningRemoteHostChanged, algoStr, keyFingerprintStr, kc.m.String())
return ErrUnmatchKey
}
// If we get this far, we haven't matched on any of the hostname patterns,
// so it's considered a new key. Prompt the user to trust it.
if !kc.trustHost(remoteAddr, algoStr, keyFingerprintStr) {
fmt.Fprintln(os.Stderr, "Host key verification failed.")
return ErrUntrustHost
}
if err := kc.m.PutHostKey(remoteAddr, key); err != nil {
fmt.Fprintf(os.Stderr, "Failed to add the host to the list of known hosts (%v).\n", kc.m)
return nil
}
fmt.Fprintf(os.Stderr, "Warning: Permanently added '%v' (%v) to the list of known hosts.\n", remoteAddr, algoStr)
return nil
}
func (inst *instance) hostKeyCallback(hostname string, remote net.Addr, key ssh.PublicKey) error {
oldPublicKey, err := hex.DecodeString(inst.conn.Options.SSHPublicKey)
if err != nil {
return errors.New("XML is corrupt: " + err.Error())
}
newPublicKey := key.Marshal()
//TODO correctly marshal/unmarshal into xml
newPublicMD5 := md5.Sum(newPublicKey)
newPublicString := hex.EncodeToString(newPublicMD5[:])
if len(oldPublicKey) == 0 {
color.Yellowln("Registering new SSH Public Key", key.Type(),
newPublicString)
inst.conn.Options.SSHPublicKey = hex.EncodeToString(newPublicKey)
inst.changed = true
return nil
}
oldPublicMD5 := md5.Sum(oldPublicKey)
oldPublicString := hex.EncodeToString(oldPublicMD5[:])
same := subtle.ConstantTimeCompare(newPublicKey, oldPublicKey)
if same == 1 {
return nil
}
color.Redln("-----POSSIBLE ATTACK-----\nSSH key changed! expected (md5):",
oldPublicString,
"got:", newPublicString, "type:", key.Type())
inst.terminal.Stderr().Write([]byte("Accept change [Ny]? "))
buf := make([]byte, 128)
n, err := inst.terminal.Stdin().Read(buf)
if err != nil {
color.Yellowln("Error reading answer:", err)
return err
}
inst.terminal.Stderr().Write([]byte{'\n'})
text := strings.ToLower(string(buf[:n]))
if text == "y" || text == "yes" {
inst.conn.Options.SSHPublicKey = hex.EncodeToString(newPublicKey)
inst.changed = true
color.Yellowln("Saving new public key to connections.xml on exit.")
return nil
}
return errors.New("Public key not accepted")
}
func keyAuth(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
log.Println(conn.RemoteAddr(), "authenticate with", key.Type(), "for user", conn.User())
log.Println(base64.StdEncoding.EncodeToString(key.Marshal()))
if isValidToken(conn.User()) {
authRequestMap.Lock()
authRequestMap.matches[conn.User()] = key.Type() + " " + base64.StdEncoding.EncodeToString(key.Marshal())
authRequestMap.timestamps[conn.User()] = time.Now()
authRequestMap.Unlock()
return nil, nil
}
//Causes "Permission denied (publickey)." for openssh. How can this bubble up to the user?
return nil, errors.New("Invalid token/username.")
}
func (s *Server) auth(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
k := key.Marshal()
t := key.Type()
perm := &ssh.Permissions{
Extensions: map[string]string{
"pubKey": string(k),
"pubKeyType": t,
},
}
_, err := s.Auther(conn, key)
if err == nil {
return perm, nil
}
return nil, err
}
func keyAuthCallback(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
guid := uuid.NewV4()
ip, remotePort := parseIpPortFrom(conn)
login := SshLogin{RemoteAddr: ip,
RemotePort: remotePort,
Username: conn.User(),
Guid: guid.String(),
Version: string(conn.ClientVersion()),
PublicKey: key.Marshal(),
KeyType: string(key.Type()),
LoginType: "key",
}
go login.Save()
//log.Println("Fail to authenticate", conn, ":", err)
//return nil, errors.New("invalid authentication")
return &ssh.Permissions{Extensions: map[string]string{"guid": guid.String()}}, nil
}
// authKey records any incoming request trying to auth with an ssh key
func authKey(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
r := &AuthEvent{
Time: fmt.Sprintf("%d", time.Now().Unix()),
AuthType: "sshKey",
SrcIP: strings.Split(conn.RemoteAddr().String(), ":")[0],
DestIP: extIP,
User: conn.User(),
TypeData: fmt.Sprintf("ssh-key-type: %s client-version: %s", key.Type(), strconv.QuoteToASCII(string(conn.ClientVersion()))),
}
h := sha256.New()
h.Write(key.Marshal())
r.Credentials = base64.StdEncoding.EncodeToString(h.Sum(nil))
addToBatch(r)
return nil, errAuthenticationFailed
}
func (config BeaconConfig) checkHostKey(hostname string, remote net.Addr, key ssh.PublicKey) error {
hostPublicKeyBytes, err := ioutil.ReadFile(string(config.PublicKey))
if err != nil {
return fmt.Errorf("failed to read host public key: %s", err)
}
hostPublicKey, _, _, _, err := ssh.ParseAuthorizedKey(hostPublicKeyBytes)
if err != nil {
return fmt.Errorf("failed to parse host public key: %s", err)
}
// note: hostname/addr are not verified; they may be behind a load balancer
// so the definition gets a bit fuzzy
if hostPublicKey.Type() != key.Type() || !bytes.Equal(hostPublicKey.Marshal(), key.Marshal()) {
return errors.New("remote host public key mismatch")
}
return nil
}
func keyAuth(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
log.Println(conn.RemoteAddr(), "authenticate with", key.Type())
return nil, nil
}
func (k *storedHostKey) Add(key ssh.PublicKey) {
if k.keys == nil {
k.keys = map[string][]byte{}
}
k.keys[key.Type()] = key.Marshal()
}
func keyAuth(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
log.Printf("(keyAuth) >> New client conn from '%s' authenticating with '%s'\n", conn.RemoteAddr(), key.Type())
// Check if the user is allowed to connect at all (meaning: the must be a subdirectory in the 'data' dir
// matching the provided SSH username).
authorizedPubKey, err := getPubKeyForUser(conn.User())
if err != nil {
return nil, fmt.Errorf("(keyAuth) >> No pub key for user '%s' found / user not allowed to connect.", conn.User())
}
fpProvidedPubKey, err := pubKeyFingerprint(key)
if err != nil {
log.Printf("(keyAuth) >> Error: Unable to create fingerprint for provided PubKey: %s\n", err.Error())
}
log.Printf("(keyAuth) >> Fingerprint of provided PubKey : %s\n", fpProvidedPubKey)
fpAuthorizedPubKey, err := pubKeyFingerprint(authorizedPubKey)
if err != nil {
log.Printf("(keyAuth) >> Error: Unable to create fingerprint for authorized PubKey: %s\n", err.Error())
}
log.Printf("(keyAuth) >> Fingerprint of authorized PubKey: %s\n", fpAuthorizedPubKey)
// Check if username and Public Key combination is allowed to establish a connection.
if theseTwoPublicKeysAreEqual(key, authorizedPubKey) {
log.Printf("(keyAuth) >> Correct username '%s' and public key provided.", conn.User())
// Signaling success / authentication passed.
return nil, nil
}
log.Printf("(keyAuth) >> Wrong username '%s' and/or public key provided.", conn.User())
return nil, fmt.Errorf("Wrong username and/or public key.")
}
func (c *SSHCluster) hostKeyCallback(hostname string, remote net.Addr, key ssh.PublicKey) error {
if c.knownHosts == nil {
if err := c.parseKnownHosts(); err != nil {
return err
}
}
err := c.knownHosts.HostKeyCallback(hostname, remote, key)
if err == knownhosts.HostNotFoundError {
fingerprint := c.fingerprintSSHKey(key)
hostnameFormatted := hostname
remoteAddr := remote.String()
if remoteAddr != hostname {
hostnameFormatted = fmt.Sprintf("%s (%s)", hostname, remoteAddr)
}
if c.base.YesNoPrompt(fmt.Sprintf("The authenticity of host '%s' can't be established.\n%s key fingerprint is %s.\nAre you sure you want to continue connecting?", hostnameFormatted, key.Type(), fingerprint)) {
c.base.SendLog(fmt.Sprintf("Trusting '%s' with key fingerprint %s", hostnameFormatted, fingerprint))
file, err := os.OpenFile(c.knownHostsPath(), os.O_CREATE|os.O_WRONLY|os.O_APPEND, os.FileMode(0644))
if err != nil {
c.base.SendLog(fmt.Sprintf("WARNING: Can't write to %s: %s", c.knownHostsPath(), err))
} else {
defer file.Close()
}
c.knownHosts.AppendHost(hostname, key, file)
return nil
}
}
return err
}
