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binaryjwt.go
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binaryjwt.go
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package tokens
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"encoding/binary"
"fmt"
"math/big"
"sync"
"time"
"github.com/ugorji/go/codec"
enforcerconstants "go.aporeto.io/enforcerd/trireme-lib/controller/internal/enforcer/constants"
"go.aporeto.io/enforcerd/trireme-lib/controller/internal/enforcer/utils/ephemeralkeys"
"go.aporeto.io/enforcerd/trireme-lib/controller/pkg/claimsheader"
"go.aporeto.io/enforcerd/trireme-lib/controller/pkg/pkiverifier"
"go.aporeto.io/enforcerd/trireme-lib/controller/pkg/secrets"
"go.aporeto.io/enforcerd/trireme-lib/utils/cache"
localcrypto "go.aporeto.io/enforcerd/trireme-lib/utils/crypto"
)
// To generate the codecs,
// codecgen -o binarycodec.go binaryjwtclaimtypes.go
// Format of Binary Tokens
// 0 1 2 3 4
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | D |CT|E| Encoding | R (reserved) |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Signature Position | nonce |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | ... |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | token |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | ... |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Signature |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | ... |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// D [0:6] - Datapath version
// CT [6:8] - Compressed tag type
// E [8:9] - Encryption enabled
// C [9:12] - Codec selector
// R [12:32] - Reserved
// L [32:48] - Token Length
// Token bytes (equal to token length)
// Signature bytes
const (
binaryNoncePosition = 6
lengthPosition = 4
headerLength = 4
sharedKeyCacheTimeout = 5 * time.Minute
)
//ClaimsEncodedBufSize is the size of maximum buffer that is required
//for claims to be serialized into
const ClaimsEncodedBufSize = 1400
// AckPattern is added in SYN and ACK tokens.
var AckPattern = []byte("PANWIDENTITY")
var sha256KeyLength int = 32
type sharedKeyStruct struct {
sharedKeys map[string][]byte
sync.RWMutex
}
func (s *sharedKeyStruct) Get(key string) []byte {
s.RLock()
if val, ok := s.sharedKeys[key]; ok {
s.RUnlock()
return val
}
s.RUnlock()
return nil
}
func (s *sharedKeyStruct) Put(key string, val []byte) {
s.Lock()
s.sharedKeys[key] = val
s.Unlock()
time.AfterFunc(sharedKeyCacheTimeout, func() {
s.Lock()
delete(s.sharedKeys, key)
s.Unlock()
})
}
// BinaryJWTConfig configures the JWT token generator with the standard parameters. One
// configuration is assigned to each server
type BinaryJWTConfig struct {
// ValidityPeriod period of the JWT
ValidityPeriod time.Duration
// Issuer is the server that issues the JWT
Issuer string
// cache test
tokenCache cache.DataStore
// sharedKey is a cache of pre-shared keys.
sharedKeys *sharedKeyStruct
}
// NewBinaryJWT creates a new JWT token processor
func NewBinaryJWT(validity time.Duration, issuer string) (*BinaryJWTConfig, error) {
return &BinaryJWTConfig{
ValidityPeriod: validity,
Issuer: issuer,
tokenCache: cache.NewCacheWithExpiration("JWTTokenCache", validity),
sharedKeys: &sharedKeyStruct{sharedKeys: map[string][]byte{}},
}, nil
}
// DecodeSyn takes as argument the JWT token and the certificate of the issuer.
// First it verifies the certificate with the local CA pool, and the decodes
// the JWT if the certificate is trusted
func (c *BinaryJWTConfig) DecodeSyn(isSynAck bool, data []byte, privateKey *ephemeralkeys.PrivateKey, secrets secrets.Secrets, connClaims *ConnectionClaims) ([]byte, *claimsheader.ClaimsHeader, []byte, *pkiverifier.PKIControllerInfo, bool, error) {
header, nonce, token, sig, err := unpackToken(false, data)
if err != nil {
return nil, nil, nil, nil, false, err
}
// Parse the claims header.
claimsHeader := claimsheader.HeaderBytes(header).ToClaimsHeader()
// Validate the header version.
if err := c.verifyClaimsHeader(claimsHeader); err != nil {
return nil, nil, nil, nil, false, err
}
// Decode the claims to a data structure.
binaryClaims, err := decode(token)
if err != nil {
return nil, nil, nil, nil, false, err
}
//Process 314 Protocol
if len(binaryClaims.DEK) == 0 {
secretKey, controller, err := c.process314Protocol(isSynAck, token, secrets, connClaims, binaryClaims, sig)
return secretKey, claimsHeader, nonce, controller, true, err
}
//Process 500 Protocol
secretKey, controller, err := c.process500Protocol(isSynAck, token, privateKey, secrets, connClaims, binaryClaims, sig)
return secretKey, claimsHeader, nonce, controller, false, err
}
// DecodeAck decodes the ack packet token
func (c *BinaryJWTConfig) DecodeAck(proto314 bool, secretKey []byte, data []byte, connClaims *ConnectionClaims) error {
// Unpack the token first.
header, _, token, sig, err := unpackToken(true, data)
if err != nil {
return err
}
// Parse the claims header.
claimsHeader := claimsheader.HeaderBytes(header).ToClaimsHeader()
// Validate the header.
if err := c.verifyClaimsHeader(claimsHeader); err != nil {
return err
}
// Decode the claims to a data structure.
binaryClaims, err := decode(token)
if err != nil {
return err
}
if proto314 {
// Calculate the signature on the token and compare it with the incoming
// signature. Since this is simple symetric hashing this is simple.
if err := c.verifyWithSharedKey314(token, secretKey, sig); err != nil {
return err
}
} else {
if err := c.verifyWithSharedKey500(token, secretKey, sig[0:sha256KeyLength]); err != nil {
return err
}
}
CopyToConnectionClaims(binaryClaims, connClaims)
return nil
}
//CreateSynToken creates the token which is attached to the tcp syn packet.
func (c *BinaryJWTConfig) CreateSynToken(claims *ConnectionClaims, encodedBuf []byte, nonce []byte, header *claimsheader.ClaimsHeader, secrets secrets.Secrets) ([]byte, error) {
// Set the appropriate claims header
header.SetCompressionType(claimsheader.CompressionTypeV1)
header.SetDatapathVersion(claimsheader.DatapathVersion1)
// Combine the application claims with the standard claims.
// In all cases for Syn/SynAck packets we also transmit our
// public key.
allclaims := ConvertToBinaryClaims(claims, c.ValidityPeriod)
allclaims.SignerKey = secrets.TransmittedKey()
// Encode the claims in a buffer.
err := encode(allclaims, &encodedBuf)
if err != nil {
return nil, logError(ErrTokenEncodeFailed, err.Error())
}
var sig []byte
encodedBuf = append(encodedBuf, AckPattern...)
sig, err = c.sign(encodedBuf, secrets.EncodingKey().(*ecdsa.PrivateKey))
if err != nil {
return nil, err
}
// Pack and return the token.
return packToken(header.ToBytes(), nonce, encodedBuf, sig), nil
}
//CreateSynAckToken creates syn/ack token which is attached to the syn/ack packet.
func (c *BinaryJWTConfig) CreateSynAckToken(proto314 bool, claims *ConnectionClaims, encodedBuf []byte, nonce []byte, header *claimsheader.ClaimsHeader, secrets secrets.Secrets, secretKey []byte) ([]byte, error) {
// Set the appropriate claims header
header.SetCompressionType(claimsheader.CompressionTypeV1)
header.SetDatapathVersion(claimsheader.DatapathVersion1)
// Combine the application claims with the standard claims.
// In all cases for Syn/SynAck packets we also transmit our
// public key.
allclaims := ConvertToBinaryClaims(claims, c.ValidityPeriod)
allclaims.SignerKey = secrets.TransmittedKey()
// Encode the claims in a buffer.
err := encode(allclaims, &encodedBuf)
if err != nil {
return nil, logError(ErrTokenEncodeFailed, err.Error())
}
var sig []byte
encodedBuf = append(encodedBuf, AckPattern...)
if proto314 {
sig, err = hash314(encodedBuf, secretKey)
if err != nil {
return nil, err
}
} else {
sig, err = hash500(encodedBuf, secretKey)
if err != nil {
return nil, err
}
}
// Pack and return the token.
return packToken(header.ToBytes(), nonce, encodedBuf, sig), nil
}
// Randomize puts the random nonce in the syn token
func (c *BinaryJWTConfig) Randomize(token []byte, nonce []byte) error {
if len(token) < 6+NonceLength {
return logError(ErrTokenTooSmall, "token is too small")
}
copy(token[6:], nonce)
return nil
}
//CreateAckToken creates ack token which is attached to the ack packet.
func (c *BinaryJWTConfig) CreateAckToken(proto314 bool, secretKey []byte, claims *ConnectionClaims, encodedBuf []byte, header *claimsheader.ClaimsHeader) ([]byte, error) {
var pad []byte
// Combine the application claims with the standard claims
allclaims := ConvertToBinaryClaims(claims, c.ValidityPeriod)
// Encode the claims in a buffer.
err := encode(allclaims, &encodedBuf)
if err != nil {
return nil, logError(ErrTokenEncodeFailed, err.Error())
}
encodedBuf = append(encodedBuf, AckPattern...)
var sig []byte
// Sign the buffer with the pre-shared key.
if proto314 {
sig, err = hash314(encodedBuf, secretKey)
if err != nil {
return nil, err
}
pad = sig
} else {
pad = make([]byte, 64)
sig, err = hash500(encodedBuf, secretKey)
if err != nil {
return nil, err
}
copy(pad, sig)
}
// Pack and return the token.
return packToken(header.ToBytes(), nil, encodedBuf, pad), nil
}
func (c *BinaryJWTConfig) verifyClaimsHeader(h *claimsheader.ClaimsHeader) error {
if h.CompressionType() != claimsheader.CompressionTypeV1 {
return ErrCompressedTagMismatch
}
if h.DatapathVersion() != claimsheader.DatapathVersion1 {
return ErrDatapathVersionMismatch
}
return nil
}
// Sign takes in a slice of bytes and a private key, and returns a ecdsa signature.
func (c *BinaryJWTConfig) Sign(buf []byte, key *ecdsa.PrivateKey) ([]byte, error) {
return c.sign(buf, key)
}
func (c *BinaryJWTConfig) sign(buf []byte, key *ecdsa.PrivateKey) ([]byte, error) {
// Create the hash and use this for the signature. This is a SHA256 hash
// of the token.
h, err := hash500(buf, nil)
if err != nil {
return nil, logError(ErrTokenHashFailed, err.Error())
}
// Sign the hash with the private key using the ECDSA algorithm
// and properly format the resulting signature.
r, s, err := ecdsa.Sign(rand.Reader, key, h)
if err != nil {
return nil, logError(ErrTokenSignFailed, err.Error())
}
curveBits := key.Curve.Params().BitSize
keyBytes := curveBits / 8
if curveBits%8 > 0 {
keyBytes++
}
// We serialize the outpus (r and s) into big-endian byte arrays and pad
// them with zeros on the left to make sure the sizes work out. Both arrays
// must be keyBytes long, and the output must be 2*keyBytes long.
tokenBytes := make([]byte, 2*keyBytes)
rBytes := r.Bytes()
copy(tokenBytes[keyBytes-len(rBytes):], rBytes)
sBytes := s.Bytes()
copy(tokenBytes[2*keyBytes-len(sBytes):], sBytes)
return tokenBytes, nil
}
func (c *BinaryJWTConfig) verify(buf []byte, sig []byte, key *ecdsa.PublicKey) error {
if len(sig) != 64 {
return ErrInvalidSignature
}
r := big.NewInt(0).SetBytes(sig[:32])
s := big.NewInt(0).SetBytes(sig[32:])
// Create the hash and use this for the signature. This is a SHA256 hash
// of the token.
h, err := hash500(buf, nil)
if err != nil {
return logError(ErrTokenHashFailed, err.Error())
}
if verifyStatus := ecdsa.Verify(key, h, r, s); verifyStatus {
return nil
}
return ErrInvalidSignature
}
func (c *BinaryJWTConfig) getSecretKey(privateKey *ephemeralkeys.PrivateKey, remotePublicKeyString string, isV1Proto bool) ([]byte, error) {
var remotePublicKey *ecdsa.PublicKey
var err error
hashKey := privateKey.PrivateKeyString + remotePublicKeyString
secretKey := c.sharedKeys.Get(hashKey)
if secretKey != nil {
return secretKey, nil
}
if isV1Proto {
remotePublicKey, err = localcrypto.DecodePublicKeyV1([]byte(remotePublicKeyString))
if err != nil {
return nil, err
}
} else {
remotePublicKey, err = localcrypto.DecodePublicKeyV2([]byte(remotePublicKeyString))
if err != nil {
return nil, err
}
}
if secretKey, err = symmetricKey(privateKey.PrivateKey, remotePublicKey); err != nil {
return nil, err
}
c.sharedKeys.Put(hashKey, secretKey)
return secretKey, nil
}
func encode(c *BinaryJWTClaims, buf *[]byte) error {
// Encode and sign the token
if cap(*buf) != ClaimsEncodedBufSize {
return fmt.Errorf("Not enough space in byte slice")
}
var h codec.Handle = new(codec.CborHandle)
enc := codec.NewEncoderBytes(buf, h)
if err := enc.Encode(c); err != nil {
return fmt.Errorf("unable to encode message: %s", err)
}
return nil
}
func decode(buf []byte) (*BinaryJWTClaims, error) {
// Decode the token into a structure.
binaryClaims := &BinaryJWTClaims{}
var h codec.Handle = new(codec.CborHandle)
dec := codec.NewDecoderBytes(buf, h)
if err := dec.Decode(binaryClaims); err != nil {
return nil, logError(ErrTokenDecodeFailed, err.Error())
}
if binaryClaims.ExpiresAt < time.Now().Unix() {
return nil, logError(ErrTokenExpired, fmt.Sprintf("token is expired since: %s", time.Unix(binaryClaims.ExpiresAt, 0)))
}
return binaryClaims, nil
}
func packToken(header, nonce, token, sig []byte) []byte {
binaryTokenPosition := binaryNoncePosition + len(nonce)
sigPosition := binaryTokenPosition + len(token)
// Token is the concatenation of
// [Position of Signature] [nonce] [token] [signature]
data := make([]byte, sigPosition+len(sig))
// Header bytes
copy(data[0:headerLength], header)
// Length of token
binary.BigEndian.PutUint16(data[lengthPosition:], uint16(sigPosition))
// nonce not required for ack packets
if len(nonce) > 0 {
copy(data[binaryNoncePosition:], nonce)
}
// token
copy(data[binaryTokenPosition:], token)
// signature
copy(data[sigPosition:], sig)
return data
}
// unpackToken returns nonce, token, signature or error if something fails
func unpackToken(isAck bool, data []byte) ([]byte, []byte, []byte, []byte, error) {
// We must have enough data to read the length.
if len(data) < binaryNoncePosition {
return nil, nil, nil, nil, ErrInvalidTokenLength
}
header := make([]byte, headerLength)
copy(header, data[:lengthPosition])
sigPosition := int(binary.BigEndian.Uint16(data[lengthPosition : lengthPosition+2]))
// The token must be long enough to have at least 1 byte of signature.
if len(data) < sigPosition+1 || sigPosition == 0 {
return nil, nil, nil, nil, ErrMissingSignature
}
var nonce []byte
if !isAck {
nonce = make([]byte, 16)
copy(nonce, data[binaryNoncePosition:binaryNoncePosition+NonceLength])
}
// Only if nonce is found do we need to advance. So, use the
// actual length of the nonce and not just a constant here.
token := data[binaryNoncePosition+len(nonce) : sigPosition]
sig := data[sigPosition:]
return header, nonce, token, sig, nil
}
// symmetricKey returns a symmetric key for encryption
func symmetricKey(privateKey *ecdsa.PrivateKey, remotePublic *ecdsa.PublicKey) ([]byte, error) {
c := elliptic.P256()
x, _ := c.ScalarMult(remotePublic.X, remotePublic.Y, privateKey.D.Bytes())
return hash500(x.Bytes(), nil)
}
func uncompressTags(binaryClaims *BinaryJWTClaims, publicKeyClaims []string) {
binaryClaims.T = append(binaryClaims.CT, enforcerconstants.TransmitterLabel+"="+binaryClaims.ID)
for _, pc := range publicKeyClaims {
if len(pc) <= claimsheader.CompressedTagLengthV1 {
binaryClaims.T = append(binaryClaims.T, pc)
continue
}
binaryClaims.T = append(binaryClaims.T, pc[:claimsheader.CompressedTagLengthV1])
}
}