VOL-1967 move api-server to separate repository
Change-Id: I21b85be74205805be15f8a85e53a903d16785671
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go
new file mode 100644
index 0000000..9dbf96b
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/gssapi/wrapToken.go
@@ -0,0 +1,235 @@
+package gssapi
+
+import (
+ "bytes"
+ "crypto/hmac"
+ "encoding/binary"
+ "encoding/hex"
+ "errors"
+ "fmt"
+
+ "gopkg.in/jcmturner/gokrb5.v7/crypto"
+ "gopkg.in/jcmturner/gokrb5.v7/iana/keyusage"
+ "gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+/*
+From RFC 4121, section 4.2.6.2:
+
+ Use of the GSS_Wrap() call yields a token (referred as the Wrap token
+ in this document), which consists of a descriptive header, followed
+ by a body portion that contains either the input user data in
+ plaintext concatenated with the checksum, or the input user data
+ encrypted. The GSS_Wrap() token SHALL have the following format:
+
+ Octet no Name Description
+ --------------------------------------------------------------
+ 0..1 TOK_ID Identification field. Tokens emitted by
+ GSS_Wrap() contain the hex value 05 04
+ expressed in big-endian order in this
+ field.
+ 2 Flags Attributes field, as described in section
+ 4.2.2.
+ 3 Filler Contains the hex value FF.
+ 4..5 EC Contains the "extra count" field, in big-
+ endian order as described in section 4.2.3.
+ 6..7 RRC Contains the "right rotation count" in big-
+ endian order, as described in section
+ 4.2.5.
+ 8..15 SndSeqNum Sequence number field in clear text,
+ expressed in big-endian order.
+ 16..last Data Encrypted data for Wrap tokens with
+ confidentiality, or plaintext data followed
+ by the checksum for Wrap tokens without
+ confidentiality, as described in section
+ 4.2.4.
+
+Quick notes:
+ - "EC" or "Extra Count" refers to the length of the checksum.
+ - "Flags" (complete details in section 4.2.2) is a set of bits:
+ - if bit 0 is set, it means the token was sent by the acceptor (generally the kerberized service).
+ - bit 1 indicates that the token's payload is encrypted
+ - bit 2 indicates if the message is protected using a subkey defined by the acceptor.
+ - When computing checksums, EC and RRC MUST be set to 0.
+ - Wrap Tokens are not ASN.1 encoded.
+*/
+const (
+ HdrLen = 16 // Length of the Wrap Token's header
+ FillerByte byte = 0xFF
+)
+
+// WrapToken represents a GSS API Wrap token, as defined in RFC 4121.
+// It contains the header fields, the payload and the checksum, and provides
+// the logic for converting to/from bytes plus computing and verifying checksums
+type WrapToken struct {
+ // const GSS Token ID: 0x0504
+ Flags byte // contains three flags: acceptor, sealed, acceptor subkey
+ // const Filler: 0xFF
+ EC uint16 // checksum length. big-endian
+ RRC uint16 // right rotation count. big-endian
+ SndSeqNum uint64 // sender's sequence number. big-endian
+ Payload []byte // your data! :)
+ CheckSum []byte // authenticated checksum of { payload | header }
+}
+
+// Return the 2 bytes identifying a GSS API Wrap token
+func getGssWrapTokenId() *[2]byte {
+ return &[2]byte{0x05, 0x04}
+}
+
+// Marshal the WrapToken into a byte slice.
+// The payload should have been set and the checksum computed, otherwise an error is returned.
+func (wt *WrapToken) Marshal() ([]byte, error) {
+ if wt.CheckSum == nil {
+ return nil, errors.New("checksum has not been set")
+ }
+ if wt.Payload == nil {
+ return nil, errors.New("payload has not been set")
+ }
+
+ pldOffset := HdrLen // Offset of the payload in the token
+ chkSOffset := HdrLen + len(wt.Payload) // Offset of the checksum in the token
+
+ bytes := make([]byte, chkSOffset+int(wt.EC))
+ copy(bytes[0:], getGssWrapTokenId()[:])
+ bytes[2] = wt.Flags
+ bytes[3] = FillerByte
+ binary.BigEndian.PutUint16(bytes[4:6], wt.EC)
+ binary.BigEndian.PutUint16(bytes[6:8], wt.RRC)
+ binary.BigEndian.PutUint64(bytes[8:16], wt.SndSeqNum)
+ copy(bytes[pldOffset:], wt.Payload)
+ copy(bytes[chkSOffset:], wt.CheckSum)
+ return bytes, nil
+}
+
+// SetCheckSum uses the passed encryption key and key usage to compute the checksum over the payload and
+// the header, and sets the CheckSum field of this WrapToken.
+// If the payload has not been set or the checksum has already been set, an error is returned.
+func (wt *WrapToken) SetCheckSum(key types.EncryptionKey, keyUsage uint32) error {
+ if wt.Payload == nil {
+ return errors.New("payload has not been set")
+ }
+ if wt.CheckSum != nil {
+ return errors.New("checksum has already been computed")
+ }
+ chkSum, cErr := wt.computeCheckSum(key, keyUsage)
+ if cErr != nil {
+ return cErr
+ }
+ wt.CheckSum = chkSum
+ return nil
+}
+
+// ComputeCheckSum computes and returns the checksum of this token, computed using the passed key and key usage.
+// Conforms to RFC 4121 in that the checksum will be computed over { body | header },
+// with the EC and RRC flags zeroed out.
+// In the context of Kerberos Wrap tokens, mostly keyusage GSSAPI_ACCEPTOR_SEAL (=22)
+// and GSSAPI_INITIATOR_SEAL (=24) will be used.
+// Note: This will NOT update the struct's Checksum field.
+func (wt *WrapToken) computeCheckSum(key types.EncryptionKey, keyUsage uint32) ([]byte, error) {
+ if wt.Payload == nil {
+ return nil, errors.New("cannot compute checksum with uninitialized payload")
+ }
+ // Build a slice containing { payload | header }
+ checksumMe := make([]byte, HdrLen+len(wt.Payload))
+ copy(checksumMe[0:], wt.Payload)
+ copy(checksumMe[len(wt.Payload):], getChecksumHeader(wt.Flags, wt.SndSeqNum))
+
+ encType, err := crypto.GetEtype(key.KeyType)
+ if err != nil {
+ return nil, err
+ }
+ return encType.GetChecksumHash(key.KeyValue, checksumMe, keyUsage)
+}
+
+// Build a header suitable for a checksum computation
+func getChecksumHeader(flags byte, senderSeqNum uint64) []byte {
+ header := make([]byte, 16)
+ copy(header[0:], []byte{0x05, 0x04, flags, 0xFF, 0x00, 0x00, 0x00, 0x00})
+ binary.BigEndian.PutUint64(header[8:], senderSeqNum)
+ return header
+}
+
+// Verify computes the token's checksum with the provided key and usage,
+// and compares it to the checksum present in the token.
+// In case of any failure, (false, Err) is returned, with Err an explanatory error.
+func (wt *WrapToken) Verify(key types.EncryptionKey, keyUsage uint32) (bool, error) {
+ computed, cErr := wt.computeCheckSum(key, keyUsage)
+ if cErr != nil {
+ return false, cErr
+ }
+ if !hmac.Equal(computed, wt.CheckSum) {
+ return false, fmt.Errorf(
+ "checksum mismatch. Computed: %s, Contained in token: %s",
+ hex.EncodeToString(computed), hex.EncodeToString(wt.CheckSum))
+ }
+ return true, nil
+}
+
+// Unmarshal bytes into the corresponding WrapToken.
+// If expectFromAcceptor is true, we expect the token to have been emitted by the gss acceptor,
+// and will check the according flag, returning an error if the token does not match the expectation.
+func (wt *WrapToken) Unmarshal(b []byte, expectFromAcceptor bool) error {
+ // Check if we can read a whole header
+ if len(b) < 16 {
+ return errors.New("bytes shorter than header length")
+ }
+ // Is the Token ID correct?
+ if !bytes.Equal(getGssWrapTokenId()[:], b[0:2]) {
+ return fmt.Errorf("wrong Token ID. Expected %s, was %s",
+ hex.EncodeToString(getGssWrapTokenId()[:]),
+ hex.EncodeToString(b[0:2]))
+ }
+ // Check the acceptor flag
+ flags := b[2]
+ isFromAcceptor := flags&0x01 == 1
+ if isFromAcceptor && !expectFromAcceptor {
+ return errors.New("unexpected acceptor flag is set: not expecting a token from the acceptor")
+ }
+ if !isFromAcceptor && expectFromAcceptor {
+ return errors.New("expected acceptor flag is not set: expecting a token from the acceptor, not the initiator")
+ }
+ // Check the filler byte
+ if b[3] != FillerByte {
+ return fmt.Errorf("unexpected filler byte: expecting 0xFF, was %s ", hex.EncodeToString(b[3:4]))
+ }
+ checksumL := binary.BigEndian.Uint16(b[4:6])
+ // Sanity check on the checksum length
+ if int(checksumL) > len(b)-HdrLen {
+ return fmt.Errorf("inconsistent checksum length: %d bytes to parse, checksum length is %d", len(b), checksumL)
+ }
+
+ wt.Flags = flags
+ wt.EC = checksumL
+ wt.RRC = binary.BigEndian.Uint16(b[6:8])
+ wt.SndSeqNum = binary.BigEndian.Uint64(b[8:16])
+ wt.Payload = b[16 : len(b)-int(checksumL)]
+ wt.CheckSum = b[len(b)-int(checksumL):]
+ return nil
+}
+
+// NewInitiatorWrapToken builds a new initiator token (acceptor flag will be set to 0) and computes the authenticated checksum.
+// Other flags are set to 0, and the RRC and sequence number are initialized to 0.
+// Note that in certain circumstances you may need to provide a sequence number that has been defined earlier.
+// This is currently not supported.
+func NewInitiatorWrapToken(payload []byte, key types.EncryptionKey) (*WrapToken, error) {
+ encType, err := crypto.GetEtype(key.KeyType)
+ if err != nil {
+ return nil, err
+ }
+
+ token := WrapToken{
+ Flags: 0x00, // all zeroed out (this is a token sent by the initiator)
+ // Checksum size: length of output of the HMAC function, in bytes.
+ EC: uint16(encType.GetHMACBitLength() / 8),
+ RRC: 0,
+ SndSeqNum: 0,
+ Payload: payload,
+ }
+
+ if err := token.SetCheckSum(key, keyusage.GSSAPI_INITIATOR_SEAL); err != nil {
+ return nil, err
+ }
+
+ return &token, nil
+}