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flight4handler.go
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flight4handler.go
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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package dtls
import (
"context"
"crypto/rand"
"crypto/x509"
"github.com/pion/dtls/v2/internal/ciphersuite"
"github.com/pion/dtls/v2/pkg/crypto/clientcertificate"
"github.com/pion/dtls/v2/pkg/crypto/elliptic"
"github.com/pion/dtls/v2/pkg/crypto/prf"
"github.com/pion/dtls/v2/pkg/crypto/signaturehash"
"github.com/pion/dtls/v2/pkg/protocol"
"github.com/pion/dtls/v2/pkg/protocol/alert"
"github.com/pion/dtls/v2/pkg/protocol/extension"
"github.com/pion/dtls/v2/pkg/protocol/handshake"
"github.com/pion/dtls/v2/pkg/protocol/recordlayer"
)
func flight4Parse(ctx context.Context, c flightConn, state *State, cache *handshakeCache, cfg *handshakeConfig) (flightVal, *alert.Alert, error) { //nolint:gocognit
seq, msgs, ok := cache.fullPullMap(state.handshakeRecvSequence, state.cipherSuite,
handshakeCachePullRule{handshake.TypeCertificate, cfg.initialEpoch, true, true},
handshakeCachePullRule{handshake.TypeClientKeyExchange, cfg.initialEpoch, true, false},
handshakeCachePullRule{handshake.TypeCertificateVerify, cfg.initialEpoch, true, true},
)
if !ok {
// No valid message received. Keep reading
return 0, nil, nil
}
// Validate type
var clientKeyExchange *handshake.MessageClientKeyExchange
if clientKeyExchange, ok = msgs[handshake.TypeClientKeyExchange].(*handshake.MessageClientKeyExchange); !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, nil
}
if h, hasCert := msgs[handshake.TypeCertificate].(*handshake.MessageCertificate); hasCert {
state.PeerCertificates = h.Certificate
// If the client offer its certificate, just disable session resumption.
// Otherwise, we have to store the certificate identitfication and expire time.
// And we have to check whether this certificate expired, revoked or changed.
//
// https://curl.se/docs/CVE-2016-5419.html
state.SessionID = nil
}
if h, hasCertVerify := msgs[handshake.TypeCertificateVerify].(*handshake.MessageCertificateVerify); hasCertVerify {
if state.PeerCertificates == nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.NoCertificate}, errCertificateVerifyNoCertificate
}
plainText := cache.pullAndMerge(
handshakeCachePullRule{handshake.TypeClientHello, cfg.initialEpoch, true, false},
handshakeCachePullRule{handshake.TypeServerHello, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeCertificate, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeServerKeyExchange, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeCertificateRequest, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeServerHelloDone, cfg.initialEpoch, false, false},
handshakeCachePullRule{handshake.TypeCertificate, cfg.initialEpoch, true, false},
handshakeCachePullRule{handshake.TypeClientKeyExchange, cfg.initialEpoch, true, false},
)
// Verify that the pair of hash algorithm and signiture is listed.
var validSignatureScheme bool
for _, ss := range cfg.localSignatureSchemes {
if ss.Hash == h.HashAlgorithm && ss.Signature == h.SignatureAlgorithm {
validSignatureScheme = true
break
}
}
if !validSignatureScheme {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, errNoAvailableSignatureSchemes
}
if err := verifyCertificateVerify(plainText, h.HashAlgorithm, h.Signature, state.PeerCertificates); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, err
}
var chains [][]*x509.Certificate
var err error
var verified bool
if cfg.clientAuth >= VerifyClientCertIfGiven {
if chains, err = verifyClientCert(state.PeerCertificates, cfg.clientCAs); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, err
}
verified = true
}
if cfg.verifyPeerCertificate != nil {
if err := cfg.verifyPeerCertificate(state.PeerCertificates, chains); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, err
}
}
state.peerCertificatesVerified = verified
} else if state.PeerCertificates != nil {
// A certificate was received, but we haven't seen a CertificateVerify
// keep reading until we receive one
return 0, nil, nil
}
if !state.cipherSuite.IsInitialized() {
serverRandom := state.localRandom.MarshalFixed()
clientRandom := state.remoteRandom.MarshalFixed()
var err error
var preMasterSecret []byte
if state.cipherSuite.AuthenticationType() == CipherSuiteAuthenticationTypePreSharedKey {
var psk []byte
if psk, err = cfg.localPSKCallback(clientKeyExchange.IdentityHint); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
state.IdentityHint = clientKeyExchange.IdentityHint
switch state.cipherSuite.KeyExchangeAlgorithm() {
case CipherSuiteKeyExchangeAlgorithmPsk:
preMasterSecret = prf.PSKPreMasterSecret(psk)
case (CipherSuiteKeyExchangeAlgorithmPsk | CipherSuiteKeyExchangeAlgorithmEcdhe):
if preMasterSecret, err = prf.EcdhePSKPreMasterSecret(psk, clientKeyExchange.PublicKey, state.localKeypair.PrivateKey, state.localKeypair.Curve); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
default:
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, errInvalidCipherSuite
}
} else {
preMasterSecret, err = prf.PreMasterSecret(clientKeyExchange.PublicKey, state.localKeypair.PrivateKey, state.localKeypair.Curve)
if err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.IllegalParameter}, err
}
}
if state.extendedMasterSecret {
var sessionHash []byte
sessionHash, err = cache.sessionHash(state.cipherSuite.HashFunc(), cfg.initialEpoch)
if err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
state.masterSecret, err = prf.ExtendedMasterSecret(preMasterSecret, sessionHash, state.cipherSuite.HashFunc())
if err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
} else {
state.masterSecret, err = prf.MasterSecret(preMasterSecret, clientRandom[:], serverRandom[:], state.cipherSuite.HashFunc())
if err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
}
if err := state.cipherSuite.Init(state.masterSecret, clientRandom[:], serverRandom[:], false); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
cfg.writeKeyLog(keyLogLabelTLS12, clientRandom[:], state.masterSecret)
}
if len(state.SessionID) > 0 {
s := Session{
ID: state.SessionID,
Secret: state.masterSecret,
}
cfg.log.Tracef("[handshake] save new session: %x", s.ID)
if err := cfg.sessionStore.Set(state.SessionID, s); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
}
// Now, encrypted packets can be handled
if err := c.handleQueuedPackets(ctx); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
seq, msgs, ok = cache.fullPullMap(seq, state.cipherSuite,
handshakeCachePullRule{handshake.TypeFinished, cfg.initialEpoch + 1, true, false},
)
if !ok {
// No valid message received. Keep reading
return 0, nil, nil
}
state.handshakeRecvSequence = seq
if _, ok = msgs[handshake.TypeFinished].(*handshake.MessageFinished); !ok {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, nil
}
if state.cipherSuite.AuthenticationType() == CipherSuiteAuthenticationTypeAnonymous {
if cfg.verifyConnection != nil {
if err := cfg.verifyConnection(state.clone()); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, err
}
}
return flight6, nil, nil
}
switch cfg.clientAuth {
case RequireAnyClientCert:
if state.PeerCertificates == nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.NoCertificate}, errClientCertificateRequired
}
case VerifyClientCertIfGiven:
if state.PeerCertificates != nil && !state.peerCertificatesVerified {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, errClientCertificateNotVerified
}
case RequireAndVerifyClientCert:
if state.PeerCertificates == nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.NoCertificate}, errClientCertificateRequired
}
if !state.peerCertificatesVerified {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, errClientCertificateNotVerified
}
case NoClientCert, RequestClientCert:
// go to flight6
}
if cfg.verifyConnection != nil {
if err := cfg.verifyConnection(state.clone()); err != nil {
return 0, &alert.Alert{Level: alert.Fatal, Description: alert.BadCertificate}, err
}
}
return flight6, nil, nil
}
func flight4Generate(_ flightConn, state *State, _ *handshakeCache, cfg *handshakeConfig) ([]*packet, *alert.Alert, error) {
extensions := []extension.Extension{&extension.RenegotiationInfo{
RenegotiatedConnection: 0,
}}
if (cfg.extendedMasterSecret == RequestExtendedMasterSecret ||
cfg.extendedMasterSecret == RequireExtendedMasterSecret) && state.extendedMasterSecret {
extensions = append(extensions, &extension.UseExtendedMasterSecret{
Supported: true,
})
}
if state.srtpProtectionProfile != 0 {
extensions = append(extensions, &extension.UseSRTP{
ProtectionProfiles: []SRTPProtectionProfile{state.srtpProtectionProfile},
})
}
if state.cipherSuite.AuthenticationType() == CipherSuiteAuthenticationTypeCertificate {
extensions = append(extensions, &extension.SupportedPointFormats{
PointFormats: []elliptic.CurvePointFormat{elliptic.CurvePointFormatUncompressed},
})
}
selectedProto, err := extension.ALPNProtocolSelection(cfg.supportedProtocols, state.peerSupportedProtocols)
if err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.NoApplicationProtocol}, err
}
if selectedProto != "" {
extensions = append(extensions, &extension.ALPN{
ProtocolNameList: []string{selectedProto},
})
state.NegotiatedProtocol = selectedProto
}
var pkts []*packet
cipherSuiteID := uint16(state.cipherSuite.ID())
if cfg.sessionStore != nil {
state.SessionID = make([]byte, sessionLength)
if _, err := rand.Read(state.SessionID); err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
}
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageServerHello{
Version: protocol.Version1_2,
Random: state.localRandom,
SessionID: state.SessionID,
CipherSuiteID: &cipherSuiteID,
CompressionMethod: defaultCompressionMethods()[0],
Extensions: extensions,
},
},
},
})
switch {
case state.cipherSuite.AuthenticationType() == CipherSuiteAuthenticationTypeCertificate:
certificate, err := cfg.getCertificate(&ClientHelloInfo{
ServerName: state.serverName,
CipherSuites: []ciphersuite.ID{state.cipherSuite.ID()},
})
if err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.HandshakeFailure}, err
}
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageCertificate{
Certificate: certificate.Certificate,
},
},
},
})
serverRandom := state.localRandom.MarshalFixed()
clientRandom := state.remoteRandom.MarshalFixed()
// Find compatible signature scheme
signatureHashAlgo, err := signaturehash.SelectSignatureScheme(cfg.localSignatureSchemes, certificate.PrivateKey)
if err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.InsufficientSecurity}, err
}
signature, err := generateKeySignature(clientRandom[:], serverRandom[:], state.localKeypair.PublicKey, state.namedCurve, certificate.PrivateKey, signatureHashAlgo.Hash)
if err != nil {
return nil, &alert.Alert{Level: alert.Fatal, Description: alert.InternalError}, err
}
state.localKeySignature = signature
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageServerKeyExchange{
EllipticCurveType: elliptic.CurveTypeNamedCurve,
NamedCurve: state.namedCurve,
PublicKey: state.localKeypair.PublicKey,
HashAlgorithm: signatureHashAlgo.Hash,
SignatureAlgorithm: signatureHashAlgo.Signature,
Signature: state.localKeySignature,
},
},
},
})
if cfg.clientAuth > NoClientCert {
// An empty list of certificateAuthorities signals to
// the client that it may send any certificate in response
// to our request. When we know the CAs we trust, then
// we can send them down, so that the client can choose
// an appropriate certificate to give to us.
var certificateAuthorities [][]byte
if cfg.clientCAs != nil {
// nolint:staticcheck // ignoring tlsCert.RootCAs.Subjects is deprecated ERR because cert does not come from SystemCertPool and it's ok if certificate authorities is empty.
certificateAuthorities = cfg.clientCAs.Subjects()
}
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageCertificateRequest{
CertificateTypes: []clientcertificate.Type{clientcertificate.RSASign, clientcertificate.ECDSASign},
SignatureHashAlgorithms: cfg.localSignatureSchemes,
CertificateAuthoritiesNames: certificateAuthorities,
},
},
},
})
}
case cfg.localPSKIdentityHint != nil || state.cipherSuite.KeyExchangeAlgorithm().Has(CipherSuiteKeyExchangeAlgorithmEcdhe):
// To help the client in selecting which identity to use, the server
// can provide a "PSK identity hint" in the ServerKeyExchange message.
// If no hint is provided and cipher suite doesn't use elliptic curve,
// the ServerKeyExchange message is omitted.
//
// https://tools.ietf.org/html/rfc4279#section-2
srvExchange := &handshake.MessageServerKeyExchange{
IdentityHint: cfg.localPSKIdentityHint,
}
if state.cipherSuite.KeyExchangeAlgorithm().Has(CipherSuiteKeyExchangeAlgorithmEcdhe) {
srvExchange.EllipticCurveType = elliptic.CurveTypeNamedCurve
srvExchange.NamedCurve = state.namedCurve
srvExchange.PublicKey = state.localKeypair.PublicKey
}
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: srvExchange,
},
},
})
}
pkts = append(pkts, &packet{
record: &recordlayer.RecordLayer{
Header: recordlayer.Header{
Version: protocol.Version1_2,
},
Content: &handshake.Handshake{
Message: &handshake.MessageServerHelloDone{},
},
},
})
return pkts, nil, nil
}