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slackhq_nebula/cmd/nebula-cert/ca.go
2024-10-10 18:00:22 -05:00

311 lines
9.0 KiB
Go

package main
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"flag"
"fmt"
"io"
"math"
"net/netip"
"os"
"strings"
"time"
"github.com/skip2/go-qrcode"
"github.com/slackhq/nebula/cert"
"github.com/slackhq/nebula/pkclient"
"golang.org/x/crypto/ed25519"
)
type caFlags struct {
set *flag.FlagSet
name *string
duration *time.Duration
outKeyPath *string
outCertPath *string
outQRPath *string
groups *string
ips *string
subnets *string
argonMemory *uint
argonIterations *uint
argonParallelism *uint
encryption *bool
curve *string
p11url *string
}
func newCaFlags() *caFlags {
cf := caFlags{set: flag.NewFlagSet("ca", flag.ContinueOnError)}
cf.set.Usage = func() {}
cf.name = cf.set.String("name", "", "Required: name of the certificate authority")
cf.duration = cf.set.Duration("duration", time.Duration(time.Hour*8760), "Optional: amount of time the certificate should be valid for. Valid time units are seconds: \"s\", minutes: \"m\", hours: \"h\"")
cf.outKeyPath = cf.set.String("out-key", "ca.key", "Optional: path to write the private key to")
cf.outCertPath = cf.set.String("out-crt", "ca.crt", "Optional: path to write the certificate to")
cf.outQRPath = cf.set.String("out-qr", "", "Optional: output a qr code image (png) of the certificate")
cf.groups = cf.set.String("groups", "", "Optional: comma separated list of groups. This will limit which groups subordinate certs can use")
cf.ips = cf.set.String("ips", "", "Optional: comma separated list of ipv4 address and network in CIDR notation. This will limit which ipv4 addresses and networks subordinate certs can use for ip addresses")
cf.subnets = cf.set.String("subnets", "", "Optional: comma separated list of ipv4 address and network in CIDR notation. This will limit which ipv4 addresses and networks subordinate certs can use in subnets")
cf.argonMemory = cf.set.Uint("argon-memory", 2*1024*1024, "Optional: Argon2 memory parameter (in KiB) used for encrypted private key passphrase")
cf.argonParallelism = cf.set.Uint("argon-parallelism", 4, "Optional: Argon2 parallelism parameter used for encrypted private key passphrase")
cf.argonIterations = cf.set.Uint("argon-iterations", 1, "Optional: Argon2 iterations parameter used for encrypted private key passphrase")
cf.encryption = cf.set.Bool("encrypt", false, "Optional: prompt for passphrase and write out-key in an encrypted format")
cf.curve = cf.set.String("curve", "25519", "EdDSA/ECDSA Curve (25519, P256)")
cf.p11url = p11Flag(cf.set)
return &cf
}
func parseArgonParameters(memory uint, parallelism uint, iterations uint) (*cert.Argon2Parameters, error) {
if memory <= 0 || memory > math.MaxUint32 {
return nil, newHelpErrorf("-argon-memory must be be greater than 0 and no more than %d KiB", uint32(math.MaxUint32))
}
if parallelism <= 0 || parallelism > math.MaxUint8 {
return nil, newHelpErrorf("-argon-parallelism must be be greater than 0 and no more than %d", math.MaxUint8)
}
if iterations <= 0 || iterations > math.MaxUint32 {
return nil, newHelpErrorf("-argon-iterations must be be greater than 0 and no more than %d", uint32(math.MaxUint32))
}
return cert.NewArgon2Parameters(uint32(memory), uint8(parallelism), uint32(iterations)), nil
}
func ca(args []string, out io.Writer, errOut io.Writer, pr PasswordReader) error {
cf := newCaFlags()
err := cf.set.Parse(args)
if err != nil {
return err
}
isP11 := len(*cf.p11url) > 0
if err := mustFlagString("name", cf.name); err != nil {
return err
}
if !isP11 {
if err = mustFlagString("out-key", cf.outKeyPath); err != nil {
return err
}
}
if err := mustFlagString("out-crt", cf.outCertPath); err != nil {
return err
}
var kdfParams *cert.Argon2Parameters
if !isP11 && *cf.encryption {
if kdfParams, err = parseArgonParameters(*cf.argonMemory, *cf.argonParallelism, *cf.argonIterations); err != nil {
return err
}
}
if *cf.duration <= 0 {
return &helpError{"-duration must be greater than 0"}
}
var groups []string
if *cf.groups != "" {
for _, rg := range strings.Split(*cf.groups, ",") {
g := strings.TrimSpace(rg)
if g != "" {
groups = append(groups, g)
}
}
}
var ips []netip.Prefix
if *cf.ips != "" {
for _, rs := range strings.Split(*cf.ips, ",") {
rs := strings.Trim(rs, " ")
if rs != "" {
n, err := netip.ParsePrefix(rs)
if err != nil {
return newHelpErrorf("invalid ip definition: %s", err)
}
if !n.Addr().Is4() {
return newHelpErrorf("invalid ip definition: can only be ipv4, have %s", rs)
}
ips = append(ips, n)
}
}
}
var subnets []netip.Prefix
if *cf.subnets != "" {
for _, rs := range strings.Split(*cf.subnets, ",") {
rs := strings.Trim(rs, " ")
if rs != "" {
n, err := netip.ParsePrefix(rs)
if err != nil {
return newHelpErrorf("invalid subnet definition: %s", err)
}
if !n.Addr().Is4() {
return newHelpErrorf("invalid subnet definition: can only be ipv4, have %s", rs)
}
subnets = append(subnets, n)
}
}
}
var passphrase []byte
if !isP11 && *cf.encryption {
for i := 0; i < 5; i++ {
out.Write([]byte("Enter passphrase: "))
passphrase, err = pr.ReadPassword()
if err == ErrNoTerminal {
return fmt.Errorf("out-key must be encrypted interactively")
} else if err != nil {
return fmt.Errorf("error reading passphrase: %s", err)
}
if len(passphrase) > 0 {
break
}
}
if len(passphrase) == 0 {
return fmt.Errorf("no passphrase specified, remove -encrypt flag to write out-key in plaintext")
}
}
var curve cert.Curve
var pub, rawPriv []byte
var p11Client *pkclient.PKClient
if isP11 {
switch *cf.curve {
case "P256":
curve = cert.Curve_P256
default:
return fmt.Errorf("invalid curve for PKCS#11: %s", *cf.curve)
}
p11Client, err = pkclient.FromUrl(*cf.p11url)
if err != nil {
return fmt.Errorf("error while creating PKCS#11 client: %w", err)
}
defer func(client *pkclient.PKClient) {
_ = client.Close()
}(p11Client)
pub, err = p11Client.GetPubKey()
if err != nil {
return fmt.Errorf("error while getting public key with PKCS#11: %w", err)
}
} else {
switch *cf.curve {
case "25519", "X25519", "Curve25519", "CURVE25519":
curve = cert.Curve_CURVE25519
pub, rawPriv, err = ed25519.GenerateKey(rand.Reader)
if err != nil {
return fmt.Errorf("error while generating ed25519 keys: %s", err)
}
case "P256":
var key *ecdsa.PrivateKey
curve = cert.Curve_P256
key, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return fmt.Errorf("error while generating ecdsa keys: %s", err)
}
// ecdh.PrivateKey lets us get at the encoded bytes, even though
// we aren't using ECDH here.
eKey, err := key.ECDH()
if err != nil {
return fmt.Errorf("error while converting ecdsa key: %s", err)
}
rawPriv = eKey.Bytes()
pub = eKey.PublicKey().Bytes()
default:
return fmt.Errorf("invalid curve: %s", *cf.curve)
}
}
t := &cert.TBSCertificate{
Version: cert.Version1,
Name: *cf.name,
Groups: groups,
Networks: ips,
UnsafeNetworks: subnets,
NotBefore: time.Now(),
NotAfter: time.Now().Add(*cf.duration),
PublicKey: pub,
IsCA: true,
Curve: curve,
}
if !isP11 {
if _, err := os.Stat(*cf.outKeyPath); err == nil {
return fmt.Errorf("refusing to overwrite existing CA key: %s", *cf.outKeyPath)
}
}
if _, err := os.Stat(*cf.outCertPath); err == nil {
return fmt.Errorf("refusing to overwrite existing CA cert: %s", *cf.outCertPath)
}
var c cert.Certificate
var b []byte
if isP11 {
c, err = t.SignPkcs11(nil, curve, p11Client)
if err != nil {
return fmt.Errorf("error while signing with PKCS#11: %w", err)
}
} else {
c, err = t.Sign(nil, curve, rawPriv)
if err != nil {
return fmt.Errorf("error while signing: %s", err)
}
if *cf.encryption {
b, err = cert.EncryptAndMarshalSigningPrivateKey(curve, rawPriv, passphrase, kdfParams)
if err != nil {
return fmt.Errorf("error while encrypting out-key: %s", err)
}
} else {
b = cert.MarshalSigningPrivateKeyToPEM(curve, rawPriv)
}
err = os.WriteFile(*cf.outKeyPath, b, 0600)
if err != nil {
return fmt.Errorf("error while writing out-key: %s", err)
}
}
b, err = c.MarshalPEM()
if err != nil {
return fmt.Errorf("error while marshalling certificate: %s", err)
}
err = os.WriteFile(*cf.outCertPath, b, 0600)
if err != nil {
return fmt.Errorf("error while writing out-crt: %s", err)
}
if *cf.outQRPath != "" {
b, err = qrcode.Encode(string(b), qrcode.Medium, -5)
if err != nil {
return fmt.Errorf("error while generating qr code: %s", err)
}
err = os.WriteFile(*cf.outQRPath, b, 0600)
if err != nil {
return fmt.Errorf("error while writing out-qr: %s", err)
}
}
return nil
}
func caSummary() string {
return "ca <flags>: create a self signed certificate authority"
}
func caHelp(out io.Writer) {
cf := newCaFlags()
out.Write([]byte("Usage of " + os.Args[0] + " " + caSummary() + "\n"))
cf.set.SetOutput(out)
cf.set.PrintDefaults()
}