mirror of
https://github.com/slackhq/nebula.git
synced 2025-01-11 03:48:12 +00:00
621 lines
16 KiB
Go
621 lines
16 KiB
Go
package cert
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import (
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"bytes"
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"crypto/ecdh"
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"crypto/ecdsa"
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"crypto/ed25519"
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"crypto/elliptic"
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"crypto/sha256"
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"encoding/hex"
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"encoding/json"
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"encoding/pem"
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"fmt"
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"net/netip"
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"slices"
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"time"
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"golang.org/x/crypto/cryptobyte"
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"golang.org/x/crypto/cryptobyte/asn1"
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"golang.org/x/crypto/curve25519"
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)
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//TODO: should we avoid hex encoding shit on output? Just let it be base64?
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const (
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classConstructed = 0x20
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classContextSpecific = 0x80
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TagCertDetails = 0 | classConstructed | classContextSpecific
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TagCertCurve = 1 | classContextSpecific
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TagCertPublicKey = 2 | classContextSpecific
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TagCertSignature = 3 | classContextSpecific
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TagDetailsName = 0 | classContextSpecific
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TagDetailsNetworks = 1 | classConstructed | classContextSpecific
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TagDetailsUnsafeNetworks = 2 | classConstructed | classContextSpecific
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TagDetailsGroups = 3 | classConstructed | classContextSpecific
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TagDetailsIsCA = 4 | classContextSpecific
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TagDetailsNotBefore = 5 | classContextSpecific
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TagDetailsNotAfter = 6 | classContextSpecific
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TagDetailsIssuer = 7 | classContextSpecific
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)
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const (
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// MaxCertificateSize is the maximum length a valid certificate can be
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MaxCertificateSize = 65536
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// MaxNameLength is limited to a maximum realistic DNS domain name to help facilitate DNS systems
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MaxNameLength = 253
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// MaxNetworkLength is the maximum length a network value can be.
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// 16 bytes for an ipv6 address + 1 byte for the prefix length
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MaxNetworkLength = 17
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)
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type certificateV2 struct {
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details detailsV2
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// RawDetails contains the entire asn.1 DER encoded Details struct
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// This is to benefit forwards compatibility in signature checking.
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// signature(RawDetails + Curve + PublicKey) == Signature
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rawDetails []byte
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curve Curve
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publicKey []byte
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signature []byte
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}
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type detailsV2 struct {
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name string
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networks []netip.Prefix
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unsafeNetworks []netip.Prefix
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groups []string
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isCA bool
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notBefore time.Time
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notAfter time.Time
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issuer string
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}
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func (c *certificateV2) Version() Version {
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return Version2
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}
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func (c *certificateV2) Curve() Curve {
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return c.curve
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}
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func (c *certificateV2) Groups() []string {
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return c.details.groups
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}
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func (c *certificateV2) IsCA() bool {
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return c.details.isCA
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}
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func (c *certificateV2) Issuer() string {
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return c.details.issuer
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}
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func (c *certificateV2) Name() string {
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return c.details.name
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}
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func (c *certificateV2) Networks() []netip.Prefix {
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return c.details.networks
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}
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func (c *certificateV2) NotAfter() time.Time {
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return c.details.notAfter
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}
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func (c *certificateV2) NotBefore() time.Time {
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return c.details.notBefore
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}
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func (c *certificateV2) PublicKey() []byte {
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return c.publicKey
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}
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func (c *certificateV2) Signature() []byte {
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return c.signature
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}
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func (c *certificateV2) UnsafeNetworks() []netip.Prefix {
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return c.details.unsafeNetworks
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}
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func (c *certificateV2) Fingerprint() (string, error) {
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b := make([]byte, len(c.rawDetails)+1+len(c.publicKey))
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//TODO: double check this, panic on empty raw details
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copy(b, c.rawDetails)
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b[len(c.rawDetails)] = byte(c.curve)
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copy(b[len(c.rawDetails)+1:], c.publicKey)
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copy(b[len(c.rawDetails)+1+len(c.publicKey):], c.signature)
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sum := sha256.Sum256(b)
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return hex.EncodeToString(sum[:]), nil
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}
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func (c *certificateV2) CheckSignature(key []byte) bool {
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b := make([]byte, len(c.rawDetails)+1+len(c.publicKey))
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//TODO: double check this, panic on empty raw details
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copy(b, c.rawDetails)
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b[len(c.rawDetails)] = byte(c.curve)
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copy(b[len(c.rawDetails)+1:], c.publicKey)
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switch c.curve {
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case Curve_CURVE25519:
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return ed25519.Verify(key, b, c.signature)
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case Curve_P256:
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//TODO: NewPublicKey
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x, y := elliptic.Unmarshal(elliptic.P256(), key)
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pubKey := &ecdsa.PublicKey{Curve: elliptic.P256(), X: x, Y: y}
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hashed := sha256.Sum256(b)
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return ecdsa.VerifyASN1(pubKey, hashed[:], c.signature)
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default:
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return false
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}
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}
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func (c *certificateV2) Expired(t time.Time) bool {
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return c.details.notBefore.After(t) || c.details.notAfter.Before(t)
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}
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func (c *certificateV2) VerifyPrivateKey(curve Curve, key []byte) error {
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if curve != c.curve {
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return fmt.Errorf("curve in cert and private key supplied don't match")
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}
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if c.details.isCA {
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switch curve {
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case Curve_CURVE25519:
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// the call to PublicKey below will panic slice bounds out of range otherwise
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if len(key) != ed25519.PrivateKeySize {
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return fmt.Errorf("key was not 64 bytes, is invalid ed25519 private key")
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}
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if !ed25519.PublicKey(c.publicKey).Equal(ed25519.PrivateKey(key).Public()) {
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return fmt.Errorf("public key in cert and private key supplied don't match")
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}
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case Curve_P256:
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privkey, err := ecdh.P256().NewPrivateKey(key)
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if err != nil {
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return fmt.Errorf("cannot parse private key as P256")
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}
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pub := privkey.PublicKey().Bytes()
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if !bytes.Equal(pub, c.publicKey) {
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return fmt.Errorf("public key in cert and private key supplied don't match")
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}
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default:
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return fmt.Errorf("invalid curve: %s", curve)
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}
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return nil
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}
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var pub []byte
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switch curve {
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case Curve_CURVE25519:
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var err error
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pub, err = curve25519.X25519(key, curve25519.Basepoint)
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if err != nil {
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return err
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}
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case Curve_P256:
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privkey, err := ecdh.P256().NewPrivateKey(key)
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if err != nil {
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return err
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}
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pub = privkey.PublicKey().Bytes()
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default:
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return fmt.Errorf("invalid curve: %s", curve)
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}
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if !bytes.Equal(pub, c.publicKey) {
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return fmt.Errorf("public key in cert and private key supplied don't match")
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}
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return nil
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}
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func (c *certificateV2) String() string {
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b, err := json.MarshalIndent(c.marshalJSON(), "", "\t")
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if err != nil {
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return "<error marshalling certificate>"
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}
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return string(b)
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}
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func (c *certificateV2) MarshalForHandshakes() ([]byte, error) {
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var b cryptobyte.Builder
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// Outermost certificate
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b.AddASN1(asn1.SEQUENCE, func(b *cryptobyte.Builder) {
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// Add the cert details which is already marshalled
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//TODO: panic on nil rawDetails
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b.AddBytes(c.rawDetails)
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// Skipping the curve and public key since those come across in a different part of the handshake
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// Add the signature
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b.AddASN1(TagCertSignature, func(b *cryptobyte.Builder) {
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b.AddBytes(c.signature)
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})
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})
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return b.Bytes()
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}
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func (c *certificateV2) Marshal() ([]byte, error) {
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var b cryptobyte.Builder
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// Outermost certificate
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b.AddASN1(asn1.SEQUENCE, func(b *cryptobyte.Builder) {
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// Add the cert details which is already marshalled
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b.AddBytes(c.rawDetails)
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// Add the curve only if its not the default value
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if c.curve != Curve_CURVE25519 {
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b.AddASN1(TagCertCurve, func(b *cryptobyte.Builder) {
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b.AddBytes([]byte{byte(c.curve)})
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})
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}
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// Add the public key if it is not empty
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if c.publicKey != nil {
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b.AddASN1(TagCertPublicKey, func(b *cryptobyte.Builder) {
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b.AddBytes(c.publicKey)
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})
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}
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// Add the signature
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b.AddASN1(TagCertSignature, func(b *cryptobyte.Builder) {
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b.AddBytes(c.signature)
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})
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})
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return b.Bytes()
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}
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func (c *certificateV2) MarshalPEM() ([]byte, error) {
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b, err := c.Marshal()
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if err != nil {
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return nil, err
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}
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return pem.EncodeToMemory(&pem.Block{Type: CertificateV2Banner, Bytes: b}), nil
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}
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func (c *certificateV2) MarshalJSON() ([]byte, error) {
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return json.Marshal(c.marshalJSON())
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}
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func (c *certificateV2) marshalJSON() m {
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fp, _ := c.Fingerprint()
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return m{
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"details": m{
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"name": c.details.name,
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"networks": c.details.networks,
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"unsafeNetworks": c.details.unsafeNetworks,
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"groups": c.details.groups,
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"notBefore": c.details.notBefore,
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"notAfter": c.details.notAfter,
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"isCa": c.details.isCA,
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"issuer": c.details.issuer,
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},
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"version": Version2,
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"publicKey": fmt.Sprintf("%x", c.publicKey),
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"curve": c.curve.String(),
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"fingerprint": fp,
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"signature": fmt.Sprintf("%x", c.Signature()),
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}
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}
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func (c *certificateV2) Copy() Certificate {
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nc := &certificateV2{
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details: detailsV2{
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name: c.details.name,
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groups: make([]string, len(c.details.groups)),
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networks: make([]netip.Prefix, len(c.details.networks)),
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unsafeNetworks: make([]netip.Prefix, len(c.details.unsafeNetworks)),
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notBefore: c.details.notBefore,
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notAfter: c.details.notAfter,
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isCA: c.details.isCA,
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issuer: c.details.issuer,
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},
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curve: c.curve,
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publicKey: make([]byte, len(c.publicKey)),
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signature: make([]byte, len(c.signature)),
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}
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copy(nc.signature, c.signature)
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copy(nc.details.groups, c.details.groups)
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copy(nc.publicKey, c.publicKey)
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copy(nc.details.networks, c.details.networks)
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copy(nc.details.unsafeNetworks, c.details.unsafeNetworks)
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return nc
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}
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func (c *certificateV2) fromTBSCertificate(t *TBSCertificate) error {
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c.details = detailsV2{
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name: t.Name,
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networks: t.Networks,
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unsafeNetworks: t.UnsafeNetworks,
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groups: t.Groups,
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isCA: t.IsCA,
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notBefore: t.NotBefore,
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notAfter: t.NotAfter,
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issuer: t.issuer,
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}
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c.curve = t.Curve
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c.publicKey = t.PublicKey
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return nil
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}
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func (c *certificateV2) marshalForSigning() ([]byte, error) {
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d, err := c.details.Marshal()
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if err != nil {
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//TODO: annotate?
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return nil, err
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}
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c.rawDetails = d
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b := make([]byte, len(c.rawDetails)+1+len(c.publicKey))
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//TODO: double check this
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copy(b, c.rawDetails)
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b[len(c.rawDetails)] = byte(c.curve)
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copy(b[len(c.rawDetails)+1:], c.publicKey)
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return b, nil
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}
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func (c *certificateV2) setSignature(b []byte) error {
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c.signature = b
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return nil
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}
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func (d *detailsV2) Marshal() ([]byte, error) {
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var b cryptobyte.Builder
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var err error
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// Details are a structure
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b.AddASN1(TagCertDetails, func(b *cryptobyte.Builder) {
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// Add the name
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b.AddASN1(TagDetailsName, func(b *cryptobyte.Builder) {
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b.AddBytes([]byte(d.name))
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})
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// Add the networks if any exist
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if len(d.networks) > 0 {
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b.AddASN1(TagDetailsNetworks, func(b *cryptobyte.Builder) {
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for _, n := range d.networks {
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sb, innerErr := n.MarshalBinary()
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if innerErr != nil {
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// MarshalBinary never returns an error
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err = fmt.Errorf("unable to marshal network: %w", innerErr)
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return
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}
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b.AddASN1OctetString(sb)
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}
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})
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}
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// Add the unsafe networks if any exist
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if len(d.unsafeNetworks) > 0 {
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b.AddASN1(TagDetailsUnsafeNetworks, func(b *cryptobyte.Builder) {
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for _, n := range d.unsafeNetworks {
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sb, innerErr := n.MarshalBinary()
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if innerErr != nil {
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// MarshalBinary never returns an error
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err = fmt.Errorf("unable to marshal unsafe network: %w", innerErr)
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return
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}
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b.AddASN1OctetString(sb)
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}
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})
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}
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// Add groups if any exist
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if len(d.groups) > 0 {
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b.AddASN1(TagDetailsGroups, func(b *cryptobyte.Builder) {
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for _, group := range d.groups {
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b.AddASN1(asn1.UTF8String, func(b *cryptobyte.Builder) {
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b.AddBytes([]byte(group))
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})
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}
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})
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}
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// Add IsCA only if true
|
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if d.isCA {
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b.AddASN1(TagDetailsIsCA, func(b *cryptobyte.Builder) {
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b.AddUint8(0xff)
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})
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}
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// Add not before
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b.AddASN1Int64WithTag(d.notBefore.Unix(), TagDetailsNotBefore)
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|
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// Add not after
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b.AddASN1Int64WithTag(d.notAfter.Unix(), TagDetailsNotAfter)
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|
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// Add the issuer if present
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if d.issuer != "" {
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issuerBytes, innerErr := hex.DecodeString(d.issuer)
|
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if innerErr != nil {
|
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err = fmt.Errorf("failed to decode issuer: %w", innerErr)
|
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return
|
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}
|
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b.AddASN1(TagDetailsIssuer, func(b *cryptobyte.Builder) {
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b.AddBytes(issuerBytes)
|
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})
|
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}
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})
|
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|
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if err != nil {
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return nil, err
|
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}
|
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|
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return b.Bytes()
|
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}
|
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|
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func unmarshalCertificateV2(b []byte, publicKey []byte, curve Curve) (*certificateV2, error) {
|
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l := len(b)
|
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if l == 0 || l > MaxCertificateSize {
|
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return nil, ErrBadFormat
|
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}
|
|
|
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input := cryptobyte.String(b)
|
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// Open the envelope
|
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if !input.ReadASN1(&input, asn1.SEQUENCE) || input.Empty() {
|
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return nil, ErrBadFormat
|
|
}
|
|
|
|
// Grab the cert details, we need to preserve the tag and length
|
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var rawDetails cryptobyte.String
|
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if !input.ReadASN1Element(&rawDetails, TagCertDetails) || rawDetails.Empty() {
|
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return nil, ErrBadFormat
|
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}
|
|
|
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//Maybe grab the curve
|
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var rawCurve byte
|
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if !readOptionalASN1Byte(&input, &rawCurve, TagCertCurve, byte(curve)) {
|
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return nil, ErrBadFormat
|
|
}
|
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curve = Curve(rawCurve)
|
|
|
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// Maybe grab the public key
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var rawPublicKey cryptobyte.String
|
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if len(publicKey) > 0 {
|
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rawPublicKey = publicKey
|
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} else if !input.ReadOptionalASN1(&rawPublicKey, nil, TagCertPublicKey) {
|
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return nil, ErrBadFormat
|
|
}
|
|
|
|
//TODO: Assert public key length
|
|
|
|
// Grab the signature
|
|
var rawSignature cryptobyte.String
|
|
if !input.ReadASN1(&rawSignature, TagCertSignature) || rawSignature.Empty() {
|
|
return nil, ErrBadFormat
|
|
}
|
|
|
|
// Finally unmarshal the details
|
|
details, err := unmarshalDetails(rawDetails)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return &certificateV2{
|
|
details: details,
|
|
rawDetails: rawDetails,
|
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curve: curve,
|
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publicKey: rawPublicKey,
|
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signature: rawSignature,
|
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}, nil
|
|
}
|
|
|
|
func unmarshalDetails(b cryptobyte.String) (detailsV2, error) {
|
|
// Open the envelope
|
|
if !b.ReadASN1(&b, TagCertDetails) || b.Empty() {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
// Read the name
|
|
var name cryptobyte.String
|
|
if !b.ReadASN1(&name, TagDetailsName) || name.Empty() || len(name) > MaxNameLength {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
// Read the network addresses
|
|
var subString cryptobyte.String
|
|
var found bool
|
|
|
|
if !b.ReadOptionalASN1(&subString, &found, TagDetailsNetworks) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var networks []netip.Prefix
|
|
var val cryptobyte.String
|
|
if found {
|
|
for !subString.Empty() {
|
|
if !subString.ReadASN1(&val, asn1.OCTET_STRING) || val.Empty() || len(val) > MaxNetworkLength {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var n netip.Prefix
|
|
if err := n.UnmarshalBinary(val); err != nil {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
networks = append(networks, n)
|
|
}
|
|
}
|
|
|
|
// Read out any unsafe networks
|
|
if !b.ReadOptionalASN1(&subString, &found, TagDetailsUnsafeNetworks) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var unsafeNetworks []netip.Prefix
|
|
if found {
|
|
for !subString.Empty() {
|
|
if !subString.ReadASN1(&val, asn1.OCTET_STRING) || val.Empty() || len(val) > MaxNetworkLength {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var n netip.Prefix
|
|
if err := n.UnmarshalBinary(val); err != nil {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
unsafeNetworks = append(unsafeNetworks, n)
|
|
}
|
|
}
|
|
|
|
// Read out any groups
|
|
if !b.ReadOptionalASN1(&subString, &found, TagDetailsGroups) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var groups []string
|
|
if found {
|
|
for !subString.Empty() {
|
|
if !subString.ReadASN1(&val, asn1.UTF8String) || val.Empty() {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
groups = append(groups, string(val))
|
|
}
|
|
}
|
|
|
|
// Read out IsCA
|
|
var isCa bool
|
|
if !readOptionalASN1Boolean(&b, &isCa, TagDetailsIsCA, false) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
// Read not before and not after
|
|
var notBefore int64
|
|
if !b.ReadASN1Int64WithTag(¬Before, TagDetailsNotBefore) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
var notAfter int64
|
|
if !b.ReadASN1Int64WithTag(¬After, TagDetailsNotAfter) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
// Read issuer
|
|
var issuer cryptobyte.String
|
|
if !b.ReadOptionalASN1(&issuer, nil, TagDetailsIssuer) {
|
|
return detailsV2{}, ErrBadFormat
|
|
}
|
|
|
|
slices.SortFunc(networks, comparePrefix)
|
|
slices.SortFunc(unsafeNetworks, comparePrefix)
|
|
|
|
return detailsV2{
|
|
name: string(name),
|
|
networks: networks,
|
|
unsafeNetworks: unsafeNetworks,
|
|
groups: groups,
|
|
isCA: isCa,
|
|
notBefore: time.Unix(notBefore, 0),
|
|
notAfter: time.Unix(notAfter, 0),
|
|
issuer: hex.EncodeToString(issuer),
|
|
}, nil
|
|
}
|