Commit 3e5480a8 authored by Eric Chiang's avatar Eric Chiang Committed by GitHub

Merge pull request #829 from ericchiang/fix-keys-expiry

server: fix expiry detection for verification keys
parents 920f6fb5 2c4752d5
......@@ -22,8 +22,9 @@ type rotationStrategy struct {
// Time between rotations.
rotationFrequency time.Duration
// After being rotated how long can a key validate signatues?
verifyFor time.Duration
// After being rotated how long should the key be kept around for validating
// signatues?
idTokenValidFor time.Duration
// Keys are always RSA keys. Though cryptopasta recommends ECDSA keys, not every
// client may support these (e.g. github.com/coreos/go-oidc/oidc).
......@@ -35,17 +36,17 @@ func staticRotationStrategy(key *rsa.PrivateKey) rotationStrategy {
return rotationStrategy{
// Setting these values to 100 years is easier than having a flag indicating no rotation.
rotationFrequency: time.Hour * 8760 * 100,
verifyFor: time.Hour * 8760 * 100,
idTokenValidFor: time.Hour * 8760 * 100,
key: func() (*rsa.PrivateKey, error) { return key, nil },
}
}
// defaultRotationStrategy returns a strategy which rotates keys every provided period,
// holding onto the public parts for some specified amount of time.
func defaultRotationStrategy(rotationFrequency, verifyFor time.Duration) rotationStrategy {
func defaultRotationStrategy(rotationFrequency, idTokenValidFor time.Duration) rotationStrategy {
return rotationStrategy{
rotationFrequency: rotationFrequency,
verifyFor: verifyFor,
idTokenValidFor: idTokenValidFor,
key: func() (*rsa.PrivateKey, error) {
return rsa.GenerateKey(rand.Reader, 2048)
},
......@@ -128,11 +129,14 @@ func (k keyRotater) rotate() error {
return storage.Keys{}, errors.New("keys already rotated")
}
// Remove expired verification keys.
i := 0
expired := func(key storage.VerificationKey) bool {
return tNow.After(key.Expiry)
}
// Remove any verification keys that have expired.
i := 0
for _, key := range keys.VerificationKeys {
if !key.Expiry.After(tNow) {
if !expired(key) {
keys.VerificationKeys[i] = key
i++
}
......@@ -140,10 +144,15 @@ func (k keyRotater) rotate() error {
keys.VerificationKeys = keys.VerificationKeys[:i]
if keys.SigningKeyPub != nil {
// Move current signing key to a verification only key.
// Move current signing key to a verification only key, throwing
// away the private part.
verificationKey := storage.VerificationKey{
PublicKey: keys.SigningKeyPub,
Expiry: tNow.Add(k.strategy.verifyFor),
// After demoting the signing key, keep the token around for at least
// the amount of time an ID Token is valid for. This ensures the
// verification key won't expire until all ID Tokens it's signed
// expired as well.
Expiry: tNow.Add(k.strategy.idTokenValidFor),
}
keys.VerificationKeys = append(keys.VerificationKeys, verificationKey)
}
......
package server
import (
"os"
"sort"
"testing"
"time"
"github.com/Sirupsen/logrus"
"github.com/coreos/dex/storage"
"github.com/coreos/dex/storage/memory"
)
func signingKeyID(t *testing.T, s storage.Storage) string {
keys, err := s.GetKeys()
if err != nil {
t.Fatal(err)
}
return keys.SigningKey.KeyID
}
func verificationKeyIDs(t *testing.T, s storage.Storage) (ids []string) {
keys, err := s.GetKeys()
if err != nil {
t.Fatal(err)
}
for _, key := range keys.VerificationKeys {
ids = append(ids, key.PublicKey.KeyID)
}
return ids
}
// slicesEq compare two string slices without modifying the ordering
// of the slices.
func slicesEq(s1, s2 []string) bool {
if len(s1) != len(s2) {
return false
}
cp := func(s []string) []string {
c := make([]string, len(s))
copy(c, s)
return c
}
cp1 := cp(s1)
cp2 := cp(s2)
sort.Strings(cp1)
sort.Strings(cp2)
for i, el := range cp1 {
if el != cp2[i] {
return false
}
}
return true
}
func TestKeyRotater(t *testing.T) {
now := time.Now()
delta := time.Millisecond
rotationFrequency := time.Second * 5
validFor := time.Second * 21
// Only the last 5 verification keys are expected to be kept around.
maxVerificationKeys := 5
l := &logrus.Logger{
Out: os.Stderr,
Formatter: &logrus.TextFormatter{DisableColors: true},
Level: logrus.DebugLevel,
}
r := &keyRotater{
Storage: memory.New(l),
strategy: defaultRotationStrategy(rotationFrequency, validFor),
now: func() time.Time { return now },
logger: l,
}
var expVerificationKeys []string
for i := 0; i < 10; i++ {
now = now.Add(rotationFrequency + delta)
if err := r.rotate(); err != nil {
t.Fatal(err)
}
got := verificationKeyIDs(t, r.Storage)
if !slicesEq(expVerificationKeys, got) {
t.Errorf("after %d rotation, expected varification keys %q, got %q", i+1, expVerificationKeys, got)
}
expVerificationKeys = append(expVerificationKeys, signingKeyID(t, r.Storage))
if n := len(expVerificationKeys); n > maxVerificationKeys {
expVerificationKeys = expVerificationKeys[n-maxVerificationKeys:]
}
}
}
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