nebula/cert/cert.go

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package cert
import (
"bytes"
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"crypto"
"crypto/rand"
"crypto/sha256"
"encoding/binary"
"encoding/hex"
"encoding/json"
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"encoding/pem"
"fmt"
"net"
"time"
"github.com/golang/protobuf/proto"
"golang.org/x/crypto/curve25519"
"golang.org/x/crypto/ed25519"
)
const publicKeyLen = 32
const (
CertBanner = "NEBULA CERTIFICATE"
X25519PrivateKeyBanner = "NEBULA X25519 PRIVATE KEY"
X25519PublicKeyBanner = "NEBULA X25519 PUBLIC KEY"
Ed25519PrivateKeyBanner = "NEBULA ED25519 PRIVATE KEY"
Ed25519PublicKeyBanner = "NEBULA ED25519 PUBLIC KEY"
)
type NebulaCertificate struct {
Details NebulaCertificateDetails
Signature []byte
}
type NebulaCertificateDetails struct {
Name string
Ips []*net.IPNet
Subnets []*net.IPNet
Groups []string
NotBefore time.Time
NotAfter time.Time
PublicKey []byte
IsCA bool
Issuer string
// Map of groups for faster lookup
InvertedGroups map[string]struct{}
}
type m map[string]interface{}
// UnmarshalNebulaCertificate will unmarshal a protobuf byte representation of a nebula cert
func UnmarshalNebulaCertificate(b []byte) (*NebulaCertificate, error) {
if len(b) == 0 {
return nil, fmt.Errorf("nil byte array")
}
var rc RawNebulaCertificate
err := proto.Unmarshal(b, &rc)
if err != nil {
return nil, err
}
if len(rc.Details.Ips)%2 != 0 {
return nil, fmt.Errorf("encoded IPs should be in pairs, an odd number was found")
}
if len(rc.Details.Subnets)%2 != 0 {
return nil, fmt.Errorf("encoded Subnets should be in pairs, an odd number was found")
}
nc := NebulaCertificate{
Details: NebulaCertificateDetails{
Name: rc.Details.Name,
Groups: make([]string, len(rc.Details.Groups)),
Ips: make([]*net.IPNet, len(rc.Details.Ips)/2),
Subnets: make([]*net.IPNet, len(rc.Details.Subnets)/2),
NotBefore: time.Unix(rc.Details.NotBefore, 0),
NotAfter: time.Unix(rc.Details.NotAfter, 0),
PublicKey: make([]byte, len(rc.Details.PublicKey)),
IsCA: rc.Details.IsCA,
InvertedGroups: make(map[string]struct{}),
},
Signature: make([]byte, len(rc.Signature)),
}
copy(nc.Signature, rc.Signature)
copy(nc.Details.Groups, rc.Details.Groups)
nc.Details.Issuer = hex.EncodeToString(rc.Details.Issuer)
if len(rc.Details.PublicKey) < publicKeyLen {
return nil, fmt.Errorf("Public key was fewer than 32 bytes; %v", len(rc.Details.PublicKey))
}
copy(nc.Details.PublicKey, rc.Details.PublicKey)
for i, rawIp := range rc.Details.Ips {
if i%2 == 0 {
nc.Details.Ips[i/2] = &net.IPNet{IP: int2ip(rawIp)}
} else {
nc.Details.Ips[i/2].Mask = net.IPMask(int2ip(rawIp))
}
}
for i, rawIp := range rc.Details.Subnets {
if i%2 == 0 {
nc.Details.Subnets[i/2] = &net.IPNet{IP: int2ip(rawIp)}
} else {
nc.Details.Subnets[i/2].Mask = net.IPMask(int2ip(rawIp))
}
}
for _, g := range rc.Details.Groups {
nc.Details.InvertedGroups[g] = struct{}{}
}
return &nc, nil
}
// UnmarshalNebulaCertificateFromPEM will unmarshal the first pem block in a byte array, returning any non consumed data
// or an error on failure
func UnmarshalNebulaCertificateFromPEM(b []byte) (*NebulaCertificate, []byte, error) {
p, r := pem.Decode(b)
if p == nil {
return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
}
nc, err := UnmarshalNebulaCertificate(p.Bytes)
return nc, r, err
}
// MarshalX25519PrivateKey is a simple helper to PEM encode an X25519 private key
func MarshalX25519PrivateKey(b []byte) []byte {
return pem.EncodeToMemory(&pem.Block{Type: X25519PrivateKeyBanner, Bytes: b})
}
// MarshalEd25519PrivateKey is a simple helper to PEM encode an Ed25519 private key
func MarshalEd25519PrivateKey(key ed25519.PrivateKey) []byte {
return pem.EncodeToMemory(&pem.Block{Type: Ed25519PrivateKeyBanner, Bytes: key})
}
// UnmarshalX25519PrivateKey will try to pem decode an X25519 private key, returning any other bytes b
// or an error on failure
func UnmarshalX25519PrivateKey(b []byte) ([]byte, []byte, error) {
k, r := pem.Decode(b)
if k == nil {
return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
}
if k.Type != X25519PrivateKeyBanner {
return nil, r, fmt.Errorf("bytes did not contain a proper nebula X25519 private key banner")
}
if len(k.Bytes) != publicKeyLen {
return nil, r, fmt.Errorf("key was not 32 bytes, is invalid X25519 private key")
}
return k.Bytes, r, nil
}
// UnmarshalEd25519PrivateKey will try to pem decode an Ed25519 private key, returning any other bytes b
// or an error on failure
func UnmarshalEd25519PrivateKey(b []byte) (ed25519.PrivateKey, []byte, error) {
k, r := pem.Decode(b)
if k == nil {
return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
}
if k.Type != Ed25519PrivateKeyBanner {
return nil, r, fmt.Errorf("bytes did not contain a proper nebula Ed25519 private key banner")
}
if len(k.Bytes) != ed25519.PrivateKeySize {
return nil, r, fmt.Errorf("key was not 64 bytes, is invalid ed25519 private key")
}
return k.Bytes, r, nil
}
// MarshalX25519PublicKey is a simple helper to PEM encode an X25519 public key
func MarshalX25519PublicKey(b []byte) []byte {
return pem.EncodeToMemory(&pem.Block{Type: X25519PublicKeyBanner, Bytes: b})
}
// MarshalEd25519PublicKey is a simple helper to PEM encode an Ed25519 public key
func MarshalEd25519PublicKey(key ed25519.PublicKey) []byte {
return pem.EncodeToMemory(&pem.Block{Type: Ed25519PublicKeyBanner, Bytes: key})
}
// UnmarshalX25519PublicKey will try to pem decode an X25519 public key, returning any other bytes b
// or an error on failure
func UnmarshalX25519PublicKey(b []byte) ([]byte, []byte, error) {
k, r := pem.Decode(b)
if k == nil {
return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
}
if k.Type != X25519PublicKeyBanner {
return nil, r, fmt.Errorf("bytes did not contain a proper nebula X25519 public key banner")
}
if len(k.Bytes) != publicKeyLen {
return nil, r, fmt.Errorf("key was not 32 bytes, is invalid X25519 public key")
}
return k.Bytes, r, nil
}
// UnmarshalEd25519PublicKey will try to pem decode an Ed25519 public key, returning any other bytes b
// or an error on failure
func UnmarshalEd25519PublicKey(b []byte) (ed25519.PublicKey, []byte, error) {
k, r := pem.Decode(b)
if k == nil {
return nil, r, fmt.Errorf("input did not contain a valid PEM encoded block")
}
if k.Type != Ed25519PublicKeyBanner {
return nil, r, fmt.Errorf("bytes did not contain a proper nebula Ed25519 public key banner")
}
if len(k.Bytes) != ed25519.PublicKeySize {
return nil, r, fmt.Errorf("key was not 32 bytes, is invalid ed25519 public key")
}
return k.Bytes, r, nil
}
// Sign signs a nebula cert with the provided private key
func (nc *NebulaCertificate) Sign(key ed25519.PrivateKey) error {
b, err := proto.Marshal(nc.getRawDetails())
if err != nil {
return err
}
sig, err := key.Sign(rand.Reader, b, crypto.Hash(0))
if err != nil {
return err
}
nc.Signature = sig
return nil
}
// CheckSignature verifies the signature against the provided public key
func (nc *NebulaCertificate) CheckSignature(key ed25519.PublicKey) bool {
b, err := proto.Marshal(nc.getRawDetails())
if err != nil {
return false
}
return ed25519.Verify(key, b, nc.Signature)
}
// Expired will return true if the nebula cert is too young or too old compared to the provided time, otherwise false
func (nc *NebulaCertificate) Expired(t time.Time) bool {
return nc.Details.NotBefore.After(t) || nc.Details.NotAfter.Before(t)
}
// Verify will ensure a certificate is good in all respects (expiry, group membership, signature, cert blocklist, etc)
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func (nc *NebulaCertificate) Verify(t time.Time, ncp *NebulaCAPool) (bool, error) {
if ncp.IsBlocklisted(nc) {
return false, fmt.Errorf("certificate has been blocked")
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}
signer, err := ncp.GetCAForCert(nc)
if err != nil {
return false, err
}
if signer.Expired(t) {
return false, fmt.Errorf("root certificate is expired")
}
if nc.Expired(t) {
return false, fmt.Errorf("certificate is expired")
}
if !nc.CheckSignature(signer.Details.PublicKey) {
return false, fmt.Errorf("certificate signature did not match")
}
if err := nc.CheckRootConstrains(signer); err != nil {
return false, err
}
return true, nil
}
// CheckRootConstrains returns an error if the certificate violates constraints set on the root (groups, ips, subnets)
func (nc *NebulaCertificate) CheckRootConstrains(signer *NebulaCertificate) error {
// Make sure this cert wasn't valid before the root
if signer.Details.NotAfter.Before(nc.Details.NotAfter) {
return fmt.Errorf("certificate expires after signing certificate")
}
// Make sure this cert isn't valid after the root
if signer.Details.NotBefore.After(nc.Details.NotBefore) {
return fmt.Errorf("certificate is valid before the signing certificate")
}
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// If the signer has a limited set of groups make sure the cert only contains a subset
if len(signer.Details.InvertedGroups) > 0 {
for _, g := range nc.Details.Groups {
if _, ok := signer.Details.InvertedGroups[g]; !ok {
return fmt.Errorf("certificate contained a group not present on the signing ca: %s", g)
}
}
}
// If the signer has a limited set of ip ranges to issue from make sure the cert only contains a subset
if len(signer.Details.Ips) > 0 {
for _, ip := range nc.Details.Ips {
if !netMatch(ip, signer.Details.Ips) {
return fmt.Errorf("certificate contained an ip assignment outside the limitations of the signing ca: %s", ip.String())
}
}
}
// If the signer has a limited set of subnet ranges to issue from make sure the cert only contains a subset
if len(signer.Details.Subnets) > 0 {
for _, subnet := range nc.Details.Subnets {
if !netMatch(subnet, signer.Details.Subnets) {
return fmt.Errorf("certificate contained a subnet assignment outside the limitations of the signing ca: %s", subnet)
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}
}
}
return nil
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}
// VerifyPrivateKey checks that the public key in the Nebula certificate and a supplied private key match
func (nc *NebulaCertificate) VerifyPrivateKey(key []byte) error {
var dst, key32 [32]byte
copy(key32[:], key)
curve25519.ScalarBaseMult(&dst, &key32)
if !bytes.Equal(dst[:], nc.Details.PublicKey) {
return fmt.Errorf("public key in cert and private key supplied don't match")
}
return nil
}
// String will return a pretty printed representation of a nebula cert
func (nc *NebulaCertificate) String() string {
if nc == nil {
return "NebulaCertificate {}\n"
}
s := "NebulaCertificate {\n"
s += "\tDetails {\n"
s += fmt.Sprintf("\t\tName: %v\n", nc.Details.Name)
if len(nc.Details.Ips) > 0 {
s += "\t\tIps: [\n"
for _, ip := range nc.Details.Ips {
s += fmt.Sprintf("\t\t\t%v\n", ip.String())
}
s += "\t\t]\n"
} else {
s += "\t\tIps: []\n"
}
if len(nc.Details.Subnets) > 0 {
s += "\t\tSubnets: [\n"
for _, ip := range nc.Details.Subnets {
s += fmt.Sprintf("\t\t\t%v\n", ip.String())
}
s += "\t\t]\n"
} else {
s += "\t\tSubnets: []\n"
}
if len(nc.Details.Groups) > 0 {
s += "\t\tGroups: [\n"
for _, g := range nc.Details.Groups {
s += fmt.Sprintf("\t\t\t\"%v\"\n", g)
}
s += "\t\t]\n"
} else {
s += "\t\tGroups: []\n"
}
s += fmt.Sprintf("\t\tNot before: %v\n", nc.Details.NotBefore)
s += fmt.Sprintf("\t\tNot After: %v\n", nc.Details.NotAfter)
s += fmt.Sprintf("\t\tIs CA: %v\n", nc.Details.IsCA)
s += fmt.Sprintf("\t\tIssuer: %s\n", nc.Details.Issuer)
s += fmt.Sprintf("\t\tPublic key: %x\n", nc.Details.PublicKey)
s += "\t}\n"
fp, err := nc.Sha256Sum()
if err == nil {
s += fmt.Sprintf("\tFingerprint: %s\n", fp)
}
s += fmt.Sprintf("\tSignature: %x\n", nc.Signature)
s += "}"
return s
}
// getRawDetails marshals the raw details into protobuf ready struct
func (nc *NebulaCertificate) getRawDetails() *RawNebulaCertificateDetails {
rd := &RawNebulaCertificateDetails{
Name: nc.Details.Name,
Groups: nc.Details.Groups,
NotBefore: nc.Details.NotBefore.Unix(),
NotAfter: nc.Details.NotAfter.Unix(),
PublicKey: make([]byte, len(nc.Details.PublicKey)),
IsCA: nc.Details.IsCA,
}
for _, ipNet := range nc.Details.Ips {
rd.Ips = append(rd.Ips, ip2int(ipNet.IP), ip2int(ipNet.Mask))
}
for _, ipNet := range nc.Details.Subnets {
rd.Subnets = append(rd.Subnets, ip2int(ipNet.IP), ip2int(ipNet.Mask))
}
copy(rd.PublicKey, nc.Details.PublicKey[:])
// I know, this is terrible
rd.Issuer, _ = hex.DecodeString(nc.Details.Issuer)
return rd
}
// Marshal will marshal a nebula cert into a protobuf byte array
func (nc *NebulaCertificate) Marshal() ([]byte, error) {
rc := RawNebulaCertificate{
Details: nc.getRawDetails(),
Signature: nc.Signature,
}
return proto.Marshal(&rc)
}
// MarshalToPEM will marshal a nebula cert into a protobuf byte array and pem encode the result
func (nc *NebulaCertificate) MarshalToPEM() ([]byte, error) {
b, err := nc.Marshal()
if err != nil {
return nil, err
}
return pem.EncodeToMemory(&pem.Block{Type: CertBanner, Bytes: b}), nil
}
// Sha256Sum calculates a sha-256 sum of the marshaled certificate
func (nc *NebulaCertificate) Sha256Sum() (string, error) {
b, err := nc.Marshal()
if err != nil {
return "", err
}
sum := sha256.Sum256(b)
return hex.EncodeToString(sum[:]), nil
}
func (nc *NebulaCertificate) MarshalJSON() ([]byte, error) {
toString := func(ips []*net.IPNet) []string {
s := []string{}
for _, ip := range ips {
s = append(s, ip.String())
}
return s
}
fp, _ := nc.Sha256Sum()
jc := m{
"details": m{
"name": nc.Details.Name,
"ips": toString(nc.Details.Ips),
"subnets": toString(nc.Details.Subnets),
"groups": nc.Details.Groups,
"notBefore": nc.Details.NotBefore,
"notAfter": nc.Details.NotAfter,
"publicKey": fmt.Sprintf("%x", nc.Details.PublicKey),
"isCa": nc.Details.IsCA,
"issuer": nc.Details.Issuer,
},
"fingerprint": fp,
"signature": fmt.Sprintf("%x", nc.Signature),
}
return json.Marshal(jc)
}
func netMatch(certIp *net.IPNet, rootIps []*net.IPNet) bool {
for _, net := range rootIps {
if net.Contains(certIp.IP) && maskContains(net.Mask, certIp.Mask) {
return true
}
}
return false
}
func maskContains(caMask, certMask net.IPMask) bool {
caM := maskTo4(caMask)
cM := maskTo4(certMask)
// Make sure forcing to ipv4 didn't nuke us
if caM == nil || cM == nil {
return false
}
// Make sure the cert mask is not greater than the ca mask
for i := 0; i < len(caMask); i++ {
if caM[i] > cM[i] {
return false
}
}
return true
}
func maskTo4(ip net.IPMask) net.IPMask {
if len(ip) == net.IPv4len {
return ip
}
if len(ip) == net.IPv6len && isZeros(ip[0:10]) && ip[10] == 0xff && ip[11] == 0xff {
return ip[12:16]
}
return nil
}
func isZeros(b []byte) bool {
for i := 0; i < len(b); i++ {
if b[i] != 0 {
return false
}
}
return true
}
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func ip2int(ip []byte) uint32 {
if len(ip) == 16 {
return binary.BigEndian.Uint32(ip[12:16])
}
return binary.BigEndian.Uint32(ip)
}
func int2ip(nn uint32) net.IP {
ip := make(net.IP, net.IPv4len)
binary.BigEndian.PutUint32(ip, nn)
return ip
}