mirror of
https://github.com/gravitational/teleport.git
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107 lines
3.1 KiB
Go
107 lines
3.1 KiB
Go
/*
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Copyright 2021 Gravitational, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package webauthn
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import (
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"crypto/ecdsa"
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"crypto/x509"
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"github.com/fxamacker/cbor/v2"
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"github.com/go-webauthn/webauthn/protocol/webauthncose"
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wan "github.com/go-webauthn/webauthn/webauthn"
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"github.com/gravitational/trace"
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log "github.com/sirupsen/logrus"
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"github.com/gravitational/teleport/api/types"
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)
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// curveP256CBOR is the constant for the P-256 curve in CBOR.
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// https://datatracker.ietf.org/doc/html/rfc8152#section-13.1
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const curveP256CBOR = 1
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func deviceToCredential(dev *types.MFADevice, idOnly bool) (wan.Credential, bool) {
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switch dev := dev.Device.(type) {
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case *types.MFADevice_U2F:
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var pubKeyCBOR []byte
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if !idOnly {
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var err error
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pubKeyCBOR, err = u2fDERKeyToCBOR(dev.U2F.PubKey)
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if err != nil {
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log.Warnf("WebAuthn: failed to convert U2F device key to CBOR: %v", err)
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return wan.Credential{}, false
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}
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}
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return wan.Credential{
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ID: dev.U2F.KeyHandle,
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PublicKey: pubKeyCBOR,
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Authenticator: wan.Authenticator{
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SignCount: dev.U2F.Counter,
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},
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}, true
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case *types.MFADevice_Webauthn:
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var pubKeyCBOR []byte
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if !idOnly {
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pubKeyCBOR = dev.Webauthn.PublicKeyCbor
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}
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return wan.Credential{
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ID: dev.Webauthn.CredentialId,
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PublicKey: pubKeyCBOR,
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AttestationType: dev.Webauthn.AttestationType,
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Authenticator: wan.Authenticator{
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AAGUID: dev.Webauthn.Aaguid,
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SignCount: dev.Webauthn.SignatureCounter,
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},
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}, true
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default:
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return wan.Credential{}, false
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}
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}
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func u2fDERKeyToCBOR(der []byte) ([]byte, error) {
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pubKeyI, err := x509.ParsePKIXPublicKey(der)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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// U2F device keys are guaranteed to be ECDSA/P256
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// https://fidoalliance.org/specs/fido-u2f-v1.2-ps-20170411/fido-u2f-raw-message-formats-v1.2-ps-20170411.html#h3_registration-response-message-success.
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pubKey, ok := pubKeyI.(*ecdsa.PublicKey)
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if !ok {
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return nil, trace.BadParameter("U2F public key has an unexpected type: %T", pubKeyI)
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}
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return U2FKeyToCBOR(pubKey)
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}
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// U2FKeyToCBOR transforms a DER-encoded U2F into its CBOR counterpart.
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func U2FKeyToCBOR(pubKey *ecdsa.PublicKey) ([]byte, error) {
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// X and Y coordinates must be exactly 32 bytes.
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xBytes := make([]byte, 32)
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yBytes := make([]byte, 32)
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pubKey.X.FillBytes(xBytes)
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pubKey.Y.FillBytes(yBytes)
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pubKeyCBOR, err := cbor.Marshal(&webauthncose.EC2PublicKeyData{
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PublicKeyData: webauthncose.PublicKeyData{
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KeyType: int64(webauthncose.EllipticKey),
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Algorithm: int64(webauthncose.AlgES256),
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},
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Curve: curveP256CBOR,
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XCoord: xBytes,
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YCoord: yBytes,
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})
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return pubKeyCBOR, trace.Wrap(err)
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}
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