Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

ssh: return unexpected msg error when server fails keyboard-interactive auth early #297

Closed
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions ssh/client_auth.go
Original file line number Diff line number Diff line change
Expand Up @@ -555,6 +555,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
}

gotMsgExtInfo := false
gotUserAuthInfoRequest := false
for {
packet, err := c.readPacket()
if err != nil {
Expand Down Expand Up @@ -585,6 +586,9 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
if msg.PartialSuccess {
return authPartialSuccess, msg.Methods, nil
}
if !gotUserAuthInfoRequest {
return authFailure, msg.Methods, unexpectedMessageError(msgUserAuthInfoRequest, packet[0])
}
return authFailure, msg.Methods, nil
case msgUserAuthSuccess:
return authSuccess, nil, nil
Expand All @@ -596,6 +600,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe
if err := Unmarshal(packet, &msg); err != nil {
return authFailure, nil, err
}
gotUserAuthInfoRequest = true

// Manually unpack the prompt/echo pairs.
rest := msg.Prompts
Expand Down
89 changes: 89 additions & 0 deletions ssh/client_auth_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -1293,3 +1293,92 @@ func TestCertAuthOpenSSHCompat(t *testing.T) {
t.Fatalf("unable to dial remote side: %s", err)
}
}

func TestKeyboardInteractiveAuthEarlyFail(t *testing.T) {
const maxAuthTries = 2

c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()

// Start testserver
serverConfig := &ServerConfig{
MaxAuthTries: maxAuthTries,
KeyboardInteractiveCallback: func(c ConnMetadata,
client KeyboardInteractiveChallenge) (*Permissions, error) {
// Fail keyboard-interactive authentication early before
// any prompt is sent to client.
return nil, errors.New("keyboard-interactive auth failed")
},
PasswordCallback: func(c ConnMetadata,
pass []byte) (*Permissions, error) {
if string(pass) == clientPassword {
return nil, nil
}
return nil, errors.New("password auth failed")
},
}
serverConfig.AddHostKey(testSigners["rsa"])

serverDone := make(chan struct{})
go func() {
defer func() { serverDone <- struct{}{} }()
conn, chans, reqs, err := NewServerConn(c2, serverConfig)
if err != nil {
return
}
_ = conn.Close()

discarderDone := make(chan struct{})
go func() {
defer func() { discarderDone <- struct{}{} }()
DiscardRequests(reqs)
}()
for newChannel := range chans {
newChannel.Reject(Prohibited,
"testserver not accepting requests")
}

<-discarderDone
}()

// Connect to testserver, expect KeyboardInteractive() to be not called,
// PasswordCallback() to be called and connection to succeed.
passwordCallbackCalled := false
clientConfig := &ClientConfig{
User: "testuser",
Auth: []AuthMethod{
RetryableAuthMethod(KeyboardInteractive(func(name,
instruction string, questions []string,
echos []bool) ([]string, error) {
t.Errorf("unexpected call to KeyboardInteractive()")
return []string{clientPassword}, nil
}), maxAuthTries),
RetryableAuthMethod(PasswordCallback(func() (secret string,
err error) {
t.Logf("PasswordCallback()")
passwordCallbackCalled = true
return clientPassword, nil
}), maxAuthTries),
},
HostKeyCallback: InsecureIgnoreHostKey(),
}

conn, _, _, err := NewClientConn(c1, "", clientConfig)
if err != nil {
t.Errorf("unexpected NewClientConn() error: %v", err)
}
if conn != nil {
conn.Close()
}

// Wait for server to finish.
<-serverDone

if !passwordCallbackCalled {
t.Errorf("expected PasswordCallback() to be called")
}
}