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fix(credssp): server side CresSSP + SPNEGO + NTLM #689

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Merged
Benoît Cortier (CBenoit) merged 1 commit into from
Jun 17, 2026
+106 −35
Merged

fix(credssp): server side CresSSP + SPNEGO + NTLM #689

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100 changes: 65 additions & 35 deletions src/credssp/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -166,6 +166,7 @@ impl EarlyUserAuthResult {
enum CredSspState {
NegoToken,
AuthInfo,
PubKeyInfo,
Final,
}

Expand Down Expand Up @@ -412,7 +413,7 @@ impl CredSspClient {

Ok(ClientState::FinalMessage(ts_request))
}
CredSspState::Final => Err(Error::new(
CredSspState::Final | CredSspState::PubKeyInfo => Err(Error::new(
ErrorKind::OutOfSequence,
"CredSSP client's 'process' method must not be fired after the 'Finished' state",
)),
Expand Down Expand Up @@ -486,6 +487,31 @@ impl<C: CredentialsProxy<AuthenticationData = AuthIdentity> + Send> CredSspServe
})
}

fn exchange_pub_key_auth(
&mut self,
pub_key_auth: &[u8],
client_nonce: &Option<[u8; NONCE_SIZE]>,
) -> crate::Result<Vec<u8>> {
let peer_version = self
.context
.as_ref()
.unwrap()
.peer_version
.expect("an decrypt public key server function cannot be fired without any incoming TSRequest");

let context = self.context.as_mut().unwrap();

context.decrypt_public_key(
&self.public_key,
pub_key_auth,
EndpointType::Server,
client_nonce,
peer_version,
)?;

context.encrypt_public_key(&self.public_key, EndpointType::Server, client_nonce, peer_version)
}

#[instrument(fields(state = ?self.state), skip_all)]
pub fn process(
&mut self,
Expand Down Expand Up @@ -628,42 +654,22 @@ impl<C: CredentialsProxy<AuthenticationData = AuthIdentity> + Send> CredSspServe
self.context.as_mut().unwrap().sspi_context.complete_auth_token(&mut []),
ts_request
);
ts_request.nego_tokens = None;

let pub_key_auth = try_cred_ssp_server!(
ts_request.pub_key_auth.take().ok_or_else(|| {
Error::new(
ErrorKind::InvalidToken,
String::from("CredSSP server expected an encrypted public key"),
)
}),
ts_request
);
let peer_version = self.context.as_ref().unwrap().peer_version.expect(
"an decrypt public key server function cannot be fired without any incoming TSRequest",
);
try_cred_ssp_server!(
self.context.as_mut().unwrap().decrypt_public_key(
self.public_key.as_ref(),
pub_key_auth.as_ref(),
EndpointType::Server,
&ts_request.client_nonce,
peer_version,
),
ts_request
);
let pub_key_auth = try_cred_ssp_server!(
self.context.as_mut().unwrap().encrypt_public_key(
self.public_key.as_ref(),
EndpointType::Server,
&ts_request.client_nonce,
peer_version,
),
ts_request
);
ts_request.pub_key_auth = Some(pub_key_auth);
if let Some(pub_key_auth) = ts_request.pub_key_auth.as_ref() {
ts_request.nego_tokens = None;

let pub_key_auth = try_cred_ssp_server!(
self.exchange_pub_key_auth(pub_key_auth, &ts_request.client_nonce),
ts_request
);
ts_request.pub_key_auth = Some(pub_key_auth);

self.state = CredSspState::AuthInfo;
} else {
ts_request.nego_tokens = Some(output_token.remove(0).buffer);

self.state = CredSspState::AuthInfo;
self.state = CredSspState::PubKeyInfo;
}
Comment on lines +668 to +672
}
result => {
try_cred_ssp_server!(
Expand All @@ -675,10 +681,34 @@ impl<C: CredentialsProxy<AuthenticationData = AuthIdentity> + Send> CredSspServe
)
}
};

self.credentials_handle = credentials_handle;

Ok(ServerState::ReplyNeeded(ts_request))
}
CredSspState::PubKeyInfo => {
ts_request.nego_tokens = None;

let pub_key_auth = try_cred_ssp_server!(
ts_request.pub_key_auth.take().ok_or_else(|| {
Error::new(
ErrorKind::InvalidToken,
String::from("CredSSP server expected an encrypted public key"),
)
}),
ts_request
);

let pub_key_auth = try_cred_ssp_server!(
self.exchange_pub_key_auth(&pub_key_auth, &ts_request.client_nonce),
ts_request
);
ts_request.pub_key_auth = Some(pub_key_auth);

self.state = CredSspState::AuthInfo;

Ok(ServerState::ReplyNeeded(ts_request))
}
CredSspState::Final => Err(ServerError {
ts_request: Some(Box::new(ts_request)),
error: Error::new(
Expand Down
41 changes: 41 additions & 0 deletions tests/sspi/client_server/credssp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -178,3 +178,44 @@ fn credssp_kerberos() {

run_credssp(&mut client, &mut server, &identity_1, &mut network_client);
}

#[test]
fn credssp_negotiate_ntlm() {
let auth_identity = AuthIdentity {
username: Username::parse("test_user").unwrap(),
password: Secret::from("test_password".to_owned()),
};
let credentials = Credentials::AuthIdentity(auth_identity.clone());

let mut client = CredSspClient::new(
PUBLIC_KEY.to_vec(),
credentials.clone(),
CredSspMode::WithCredentials,
ClientMode::Negotiate(NegotiateConfig::new(
Box::new(NtlmConfig {
client_computer_name: Some("DESKTOP-3D83IAN.example.com".to_owned()),
}),
Some("ntlm,!kerberos,!pku2u".to_owned()),
"DESKTOP-3D83IAN.example.com".to_owned(),
)),
TARGET_NAME.to_owned(),
)
.unwrap();

let mut server = CredSspServer::new(
PUBLIC_KEY.to_vec(),
CredentialsProxyImpl::new(&auth_identity),
ServerMode::Negotiate(NegotiateConfig::new(
Box::new(NtlmConfig {
client_computer_name: Some("DESKTOP-3D83IAN.example.com".to_owned()),
}),
Some("ntlm,!kerberos,!pku2u".to_owned()),
"SERVER.example.com".to_owned(),
)),
)
.unwrap();

let mut network_client = NetworkClientMock { kdc: KdcMock::empty() };

run_credssp(&mut client, &mut server, &auth_identity, &mut network_client);
}