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go.crypto/ssh: ensure {Server,Client}Conn do not expose io.ReadWriter

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Transport should not be a ReadWriter. It can only write packets, i.e. no partial reads or writes. Furthermore, you can currently do ClientConn.Write() while the connection is live, which sends raw bytes over the connection. Doing so will confuse the transports because the data is not encrypted.

As a consequence, ClientConn and ServerConn stop being a net.Conn

Finally, ensure that {Server,Client}Conn implement LocalAddr and RemoteAddr methods that previously were exposed by an embedded net.Conn field.

R=hanwen
CC=golang-dev
https://golang.org/cl/16610043
This commit is contained in:
Dave Cheney
2013-10-25 06:29:58 +11:00
parent 105632d35b
commit c0d640c887
6 changed files with 88 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ssh/server.go
+28 -19
View File
@@ -97,8 +97,8 @@ const maxCachedPubKeys = 16
// A ServerConn represents an incoming connection.
type ServerConn struct {
*transport
config *ServerConfig
transport *transport
config *ServerConfig
channels map[uint32]*serverChan
nextChanId uint32
@@ -147,6 +147,15 @@ func signAndMarshal(k Signer, rand io.Reader, data []byte) ([]byte, error) {
return serializeSignature(k.PublicKey().PrivateKeyAlgo(), sig), nil
}
// Close closes the connection.
func (s *ServerConn) Close() error { return s.transport.Close() }
// LocalAddr returns the local network address.
func (c *ServerConn) LocalAddr() net.Addr { return c.transport.LocalAddr() }
// RemoteAddr returns the remote network address.
func (c *ServerConn) RemoteAddr() net.Addr { return c.transport.RemoteAddr() }
// Handshake performs an SSH transport and client authentication on the given ServerConn.
func (s *ServerConn) Handshake() error {
var err error
@@ -160,7 +169,7 @@ func (s *ServerConn) Handshake() error {
}
var packet []byte
if packet, err = s.readPacket(); err != nil {
if packet, err = s.transport.readPacket(); err != nil {
return err
}
var serviceRequest serviceRequestMsg
@@ -173,7 +182,7 @@ func (s *ServerConn) Handshake() error {
serviceAccept := serviceAcceptMsg{
Service: serviceUserAuth,
}
if err := s.writePacket(marshal(msgServiceAccept, serviceAccept)); err != nil {
if err := s.transport.writePacket(marshal(msgServiceAccept, serviceAccept)); err != nil {
return err
}
@@ -199,13 +208,13 @@ func (s *ServerConn) clientInitHandshake(clientKexInit *kexInitMsg, clientKexIni
}
serverKexInitPacket := marshal(msgKexInit, serverKexInit)
if err = s.writePacket(serverKexInitPacket); err != nil {
if err = s.transport.writePacket(serverKexInitPacket); err != nil {
return
}
if clientKexInitPacket == nil {
clientKexInit = new(kexInitMsg)
if clientKexInitPacket, err = s.readPacket(); err != nil {
if clientKexInitPacket, err = s.transport.readPacket(); err != nil {
return
}
if err = unmarshal(clientKexInit, clientKexInitPacket, msgKexInit); err != nil {
@@ -221,7 +230,7 @@ func (s *ServerConn) clientInitHandshake(clientKexInit *kexInitMsg, clientKexIni
if clientKexInit.FirstKexFollows && algs.kex != clientKexInit.KexAlgos[0] {
// The client sent a Kex message for the wrong algorithm,
// which we have to ignore.
if _, err = s.readPacket(); err != nil {
if _, err = s.transport.readPacket(); err != nil {
return
}
}
@@ -244,7 +253,7 @@ func (s *ServerConn) clientInitHandshake(clientKexInit *kexInitMsg, clientKexIni
serverKexInit: marshal(msgKexInit, serverKexInit),
clientKexInit: clientKexInitPacket,
}
result, err := kex.Server(s, s.config.rand(), &magics, hostKey)
result, err := kex.Server(s.transport, s.config.rand(), &magics, hostKey)
if err != nil {
return err
}
@@ -253,10 +262,10 @@ func (s *ServerConn) clientInitHandshake(clientKexInit *kexInitMsg, clientKexIni
return err
}
if err = s.writePacket([]byte{msgNewKeys}); err != nil {
if err = s.transport.writePacket([]byte{msgNewKeys}); err != nil {
return
}
if packet, err := s.readPacket(); err != nil {
if packet, err := s.transport.readPacket(); err != nil {
return err
} else if packet[0] != msgNewKeys {
return UnexpectedMessageError{msgNewKeys, packet[0]}
@@ -308,7 +317,7 @@ func (s *ServerConn) authenticate(H []byte) error {
userAuthLoop:
for {
if packet, err = s.readPacket(); err != nil {
if packet, err = s.transport.readPacket(); err != nil {
return err
}
if err = unmarshal(&userAuthReq, packet, msgUserAuthRequest); err != nil {
@@ -382,7 +391,7 @@ userAuthLoop:
Algo: algo,
PubKey: string(pubKey),
}
if err = s.writePacket(marshal(msgUserAuthPubKeyOk, okMsg)); err != nil {
if err = s.transport.writePacket(marshal(msgUserAuthPubKeyOk, okMsg)); err != nil {
return err
}
continue userAuthLoop
@@ -432,13 +441,13 @@ userAuthLoop:
return errors.New("ssh: no authentication methods configured but NoClientAuth is also false")
}
if err = s.writePacket(marshal(msgUserAuthFailure, failureMsg)); err != nil {
if err = s.transport.writePacket(marshal(msgUserAuthFailure, failureMsg)); err != nil {
return err
}
}
packet = []byte{msgUserAuthSuccess}
if err = s.writePacket(packet); err != nil {
if err = s.transport.writePacket(packet); err != nil {
return err
}
@@ -462,7 +471,7 @@ func (c *sshClientKeyboardInteractive) Challenge(user, instruction string, quest
prompts = appendBool(prompts, echos[i])
}
if err := c.writePacket(marshal(msgUserAuthInfoRequest, userAuthInfoRequestMsg{
if err := c.transport.writePacket(marshal(msgUserAuthInfoRequest, userAuthInfoRequestMsg{
Instruction: instruction,
NumPrompts: uint32(len(questions)),
Prompts: prompts,
@@ -470,7 +479,7 @@ func (c *sshClientKeyboardInteractive) Challenge(user, instruction string, quest
return nil, err
}
packet, err := c.readPacket()
packet, err := c.transport.readPacket()
if err != nil {
return nil, err
}
@@ -511,7 +520,7 @@ func (s *ServerConn) Accept() (Channel, error) {
}
for {
packet, err := s.readPacket()
packet, err := s.transport.readPacket()
if err != nil {
s.lock.Lock()
@@ -557,7 +566,7 @@ func (s *ServerConn) Accept() (Channel, error) {
}
c := &serverChan{
channel: channel{
packetConn: s,
packetConn: s.transport,
remoteId: msg.PeersId,
remoteWin: window{Cond: newCond()},
maxPacket: msg.MaxPacketSize,
@@ -619,7 +628,7 @@ func (s *ServerConn) Accept() (Channel, error) {
case *globalRequestMsg:
if msg.WantReply {
if err := s.writePacket([]byte{msgRequestFailure}); err != nil {
if err := s.transport.writePacket([]byte{msgRequestFailure}); err != nil {
return nil, err
}
}