forked from keybase/client
/
kex2_provisioner.go
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/
kex2_provisioner.go
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// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
package engine
import (
"fmt"
"time"
"github.com/keybase/client/go/kex2"
"github.com/keybase/client/go/libkb"
"github.com/keybase/client/go/msgpack"
keybase1 "github.com/keybase/client/go/protocol/keybase1"
"github.com/keybase/go-framed-msgpack-rpc/rpc"
jsonw "github.com/keybase/go-jsonw"
"golang.org/x/net/context"
)
// Kex2Provisioner is an engine.
type Kex2Provisioner struct {
libkb.Contextified
secret kex2.Secret
secretCh chan kex2.Secret
me *libkb.User
signingKey libkb.GenericKey
encryptionKey libkb.NaclDHKeyPair
pps keybase1.PassphraseStream
provisioneeDeviceName string
provisioneeDeviceType keybase1.DeviceTypeV2
mctx libkb.MetaContext
proof *jsonw.Wrapper
}
// Kex2Provisioner implements kex2.Provisioner interface.
var _ kex2.Provisioner = (*Kex2Provisioner)(nil)
// NewKex2Provisioner creates a Kex2Provisioner engine.
func NewKex2Provisioner(g *libkb.GlobalContext, secret kex2.Secret, pps *libkb.PassphraseStream) *Kex2Provisioner {
e := &Kex2Provisioner{
Contextified: libkb.NewContextified(g),
secret: secret,
secretCh: make(chan kex2.Secret),
}
if pps != nil {
e.pps = pps.Export()
}
return e
}
// Name is the unique engine name.
func (e *Kex2Provisioner) Name() string {
return "Kex2Provisioner"
}
// GetPrereqs returns the engine prereqs.
func (e *Kex2Provisioner) Prereqs() Prereqs {
return Prereqs{Device: true}
}
// RequiredUIs returns the required UIs.
func (e *Kex2Provisioner) RequiredUIs() []libkb.UIKind {
return []libkb.UIKind{
libkb.SecretUIKind,
libkb.ProvisionUIKind,
}
}
// SubConsumers returns the other UI consumers for this engine.
func (e *Kex2Provisioner) SubConsumers() []libkb.UIConsumer {
return nil
}
// Run starts the provisioner engine.
func (e *Kex2Provisioner) Run(m libkb.MetaContext) error {
// The guard is acquired later, after the potentially long pause by the user.
defer m.G().LocalSigchainGuard().Clear(m.Ctx(), "Kex2Provisioner")
// before starting provisioning, need to load some information:
if err := e.loadMe(); err != nil {
return err
}
if err := m.ActiveDevice().ClearPassphraseStreamCacheIfOutdated(m); err != nil {
return err
}
if err := e.loadSecretKeys(m); err != nil {
return err
}
// get current passphrase stream if necessary:
if e.pps.PassphraseStream == nil {
m.Debug("kex2 provisioner needs passphrase stream, getting it via GetPassphraseStreamStored")
pps, err := libkb.GetPassphraseStreamStored(m)
if err != nil {
return err
}
e.pps = pps.Export()
}
// Go's context.Context needed by some kex2 callback functions
m = m.EnsureCtx()
e.mctx = m
deviceID := m.G().Env.GetDeviceID()
// all set: start provisioner
karg := kex2.KexBaseArg{
Ctx: m.Ctx(),
LogCtx: newKex2LogContext(m.G()),
Mr: libkb.NewKexRouter(m),
DeviceID: deviceID,
Secret: e.secret,
SecretChannel: e.secretCh,
Timeout: 60 * time.Minute,
}
parg := kex2.ProvisionerArg{
KexBaseArg: karg,
Provisioner: e,
HelloTimeout: 15 * time.Second,
}
if err := kex2.RunProvisioner(parg); err != nil {
return err
}
m.G().LocalSigchainGuard().Clear(m.Ctx(), "Kex2Provisioner")
// successfully provisioned the other device
sarg := keybase1.ProvisionerSuccessArg{
DeviceName: e.provisioneeDeviceName,
DeviceType: e.provisioneeDeviceType,
}
return m.UIs().ProvisionUI.ProvisionerSuccess(context.Background(), sarg)
}
func (e *Kex2Provisioner) loadSecretKeys(m libkb.MetaContext) (err error) {
// get signing key (including secret key)
ska1 := libkb.SecretKeyArg{
Me: e.me,
KeyType: libkb.DeviceSigningKeyType,
}
e.signingKey, err = m.G().Keyrings.GetSecretKeyWithPrompt(m, m.SecretKeyPromptArg(ska1, "new device install"))
if err != nil {
return err
}
// get encryption key (including secret key)
ska2 := libkb.SecretKeyArg{
Me: e.me,
KeyType: libkb.DeviceEncryptionKeyType,
}
encryptionKeyGeneric, err := e.G().Keyrings.GetSecretKeyWithPrompt(m, m.SecretKeyPromptArg(ska2, "new device install"))
if err != nil {
return err
}
var ok bool
e.encryptionKey, ok = encryptionKeyGeneric.(libkb.NaclDHKeyPair)
if !ok {
return fmt.Errorf("Unexpected encryption key type")
}
return nil
}
// AddSecret inserts a received secret into the provisioner's
// secret channel.
func (e *Kex2Provisioner) AddSecret(s kex2.Secret) {
e.secretCh <- s
}
// GetLogFactory implements GetLogFactory in kex2.Provisioner.
func (e *Kex2Provisioner) GetLogFactory() rpc.LogFactory {
return rpc.NewSimpleLogFactory(e.G().Log, nil)
}
// GetNetworkInstrumenter implements GetNetworkInstrumenter in kex2.Provisioner.
func (e *Kex2Provisioner) GetNetworkInstrumenter() rpc.NetworkInstrumenterStorage {
return e.G().RemoteNetworkInstrumenterStorage
}
// GetHelloArg implements GetHelloArg in kex2.Provisioner.
func (e *Kex2Provisioner) GetHelloArg() (arg keybase1.HelloArg, err error) {
// Pull the metaContext out of the this object, since we can't pass it through the
// kex2/provisioner interface
m := e.mctx
defer m.Trace("Kex2Provisioner#GetHelloArg()", &err)()
_ = m.UIs().ProvisionUI.DisplaySecretExchanged(context.Background(), 0)
// get a session token that device Y can use
mctx := libkb.NewMetaContextBackground(e.G())
tokener, err := libkb.NewSessionTokener(mctx)
if err != nil {
return arg, err
}
token, csrf := tokener.Tokens()
// generate a skeleton key proof
sigBody, err := e.skeletonProof(m)
if err != nil {
return arg, err
}
// return the HelloArg
arg = keybase1.HelloArg{
Uid: e.me.GetUID(),
Pps: e.pps,
Token: keybase1.SessionToken(token),
Csrf: keybase1.CsrfToken(csrf),
SigBody: sigBody,
}
return arg, nil
}
// GetHello2Arg implements GetHello2Arg in kex2.Provisioner.
func (e *Kex2Provisioner) GetHello2Arg() (arg2 keybase1.Hello2Arg, err error) {
// Pull the metaContext out of the this object, since we can't pass it through the
// kex2/provisioner interface
m := e.mctx
defer m.Trace("Kex2Provisioner#GetHello2Arg", &err)()
var arg1 keybase1.HelloArg
arg1, err = e.GetHelloArg()
if err != nil {
return arg2, err
}
arg2 = keybase1.Hello2Arg{
Uid: arg1.Uid,
Token: arg1.Token,
Csrf: arg1.Csrf,
SigBody: arg1.SigBody,
}
return arg2, nil
}
// CounterSign implements CounterSign in kex2.Provisioner.
func (e *Kex2Provisioner) CounterSign(input keybase1.HelloRes) (sig []byte, err error) {
m := e.mctx
defer m.Trace("Kex2Provisioner#CounterSign", &err)()
jw, err := jsonw.Unmarshal([]byte(input))
if err != nil {
return nil, err
}
// check the reverse signature and put the values from the provisionee into
// e.proof
if err = e.checkReverseSig(jw); err != nil {
m.Debug("provisioner failed to verify reverse sig: %s", err)
return nil, err
}
m.Debug("provisioner verified reverse sig")
// remember some device information for ProvisionUI.ProvisionerSuccess()
if err = e.rememberDeviceInfo(e.proof); err != nil {
return nil, err
}
// sign the whole thing with provisioner's signing key
s, _, _, err := libkb.SignJSON(e.proof, e.signingKey)
if err != nil {
return nil, err
}
return []byte(s), nil
}
// CounterSign2 implements CounterSign in kex2.Provisioner.
func (e *Kex2Provisioner) CounterSign2(input keybase1.Hello2Res) (output keybase1.DidCounterSign2Arg, err error) {
m := e.mctx
defer m.Trace("Kex2Provisioner#CounterSign2", &err)()
var key libkb.GenericKey
key, err = libkb.ImportKeypairFromKID(input.EncryptionKey)
if err != nil {
return output, err
}
output.Sig, err = e.CounterSign(input.SigPayload)
if err != nil {
return output, err
}
var ppsPacked []byte
ppsPacked, err = msgpack.Encode(e.pps)
if err != nil {
return output, err
}
output.PpsEncrypted, err = key.EncryptToString(ppsPacked, nil)
// Sync the PUK, if the pukring is nil, we don't have a PUK and have
// nothing to box. We also can't make a userEKBox which is signed by the
// PUK.
pukring, err := e.syncPUK(m)
if err != nil || pukring == nil {
return output, err
}
output.PukBox, err = e.makePukBox(m, pukring, key)
if err != nil {
return output, err
}
userEKBoxStorage := m.G().GetUserEKBoxStorage()
if input.DeviceEkKID.Exists() && userEKBoxStorage != nil {
// If we error out here the provisionee will create it's own keys later
// but we shouldn't fail kex.
userEKBox, ekErr := makeUserEKBoxForProvisionee(m, input.DeviceEkKID)
if ekErr != nil {
userEKBox = nil
m.Debug("Unable to makeUserEKBox %v", ekErr)
}
output.UserEkBox = userEKBox
} else {
m.Debug("Skipping userEKBox generation empty KID or storage. KID: %v, storage: %v", input.DeviceEkKID, userEKBoxStorage)
}
return output, nil
}
// skeletonProof generates a partial key proof structure that device Y can
// fill in. When verifying the reverse signature we fill in the values from Y
// to check the reverse signature
func (e *Kex2Provisioner) skeletonProof(m libkb.MetaContext) (sigBody string, err error) {
// Set the local sigchain guard to tell background tasks
// to stay off the sigchain while we do this.
// This is released at the end of Kex2Provisioner#Run
e.G().LocalSigchainGuard().Set(context.TODO(), "Kex2Provisioner")
// reload the self user to make sure it is fresh
// (this fixes TestProvisionWithRevoke [CORE-5631, CORE-5636])
if err := e.loadMe(); err != nil {
return "", err
}
delg := libkb.Delegator{
ExistingKey: e.signingKey,
Me: e.me,
DelegationType: libkb.DelegationTypeSibkey,
Expire: libkb.NaclEdDSAExpireIn,
Contextified: libkb.NewContextified(e.G()),
}
e.proof, err = libkb.KeyProof(m, delg)
if err != nil {
return "", err
}
body, err := e.proof.Marshal()
if err != nil {
return "", err
}
return string(body), nil
}
// checkReverseSig verifies that the reverse sig in jw is valid and matches
// e.proof. The provisionee is only allowed to pass the following fields to the
// provisioner:
// body.device
// body.sibkey.kid
// The values at these paths in the json reserialized and are inserted into the
// skeleton proof that we initially passed to the provisionee so we can ensure
// no other values were added when verifying the signature.
func (e *Kex2Provisioner) checkReverseSig(jw *jsonw.Wrapper) error {
kid, err := jw.AtPath("body.sibkey.kid").GetString()
if err != nil {
return err
}
keypair, err := libkb.ImportKeypairFromKID(keybase1.KIDFromString(kid))
if err != nil {
return err
}
revsig, err := jw.AtPath("body.sibkey.reverse_sig").GetString()
if err != nil {
return err
}
// set reverse_sig to nil to verify it:
err = e.proof.SetValueAtPath("body.sibkey.reverse_sig", jsonw.NewNil())
if err != nil {
return err
}
// Copy known fields that provisionee set into e.proof
deviceWrapper := jw.AtPath("body.device")
// NOTE the time value is dropped during Export, value here is arbitrary.
device, err := libkb.ParseDevice(deviceWrapper, time.Now())
if err != nil {
return err
}
dw, err := device.Export(libkb.LinkType(libkb.DelegationTypeSibkey))
if err != nil {
return err
}
err = e.proof.SetValueAtPath("body.device", dw)
if err != nil {
return err
}
err = e.proof.SetValueAtPath("body.sibkey.kid", jsonw.NewString(kid))
if err != nil {
return err
}
msg, err := e.proof.Marshal()
if err != nil {
return err
}
_, err = keypair.VerifyString(e.G().Log, revsig, msg)
if err != nil {
return err
}
// put reverse_sig back in
return e.proof.SetValueAtPath("body.sibkey.reverse_sig", jsonw.NewString(revsig))
}
// rememberDeviceInfo saves the device name and type in
// Kex2Provisioner for later use.
func (e *Kex2Provisioner) rememberDeviceInfo(jw *jsonw.Wrapper) error {
name, err := jw.AtPath("body.device.name").GetString()
if err != nil {
return err
}
e.provisioneeDeviceName = name
dtype, err := jw.AtPath("body.device.type").GetString()
if err != nil {
return err
}
e.provisioneeDeviceType, err = keybase1.StringToDeviceTypeV2(dtype)
return err
}
// Returns nil if there are no per-user-keys.
func (e *Kex2Provisioner) syncPUK(m libkb.MetaContext) (*libkb.PerUserKeyring, error) {
pukring, err := e.G().GetPerUserKeyring(m.Ctx())
if err != nil {
return nil, err
}
if err = pukring.Sync(m); err != nil {
return nil, err
}
if !pukring.HasAnyKeys() {
return nil, nil
}
return pukring, nil
}
func (e *Kex2Provisioner) makePukBox(m libkb.MetaContext, pukring *libkb.PerUserKeyring, receiverKeyGeneric libkb.GenericKey) (*keybase1.PerUserKeyBox, error) {
receiverKey, ok := receiverKeyGeneric.(libkb.NaclDHKeyPair)
if !ok {
return nil, fmt.Errorf("Unexpected receiver key type")
}
pukBox, err := pukring.PrepareBoxForNewDevice(m,
receiverKey, // receiver key: provisionee enc
e.encryptionKey) // sender key: this device enc
return &pukBox, err
}
func (e *Kex2Provisioner) loadMe() error {
var err error
e.me, err = libkb.LoadMe(libkb.NewLoadUserArg(e.G()))
return err
}