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nebula
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remove old hmac function. superceded by ix_psk0

This commit is contained in:
Ryan Huber 2019-11-23 16:50:36 +00:00
parent ef324bf7e3
commit 6a460ba38b
5 changed files with 65 additions and 183 deletions
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10
examples/config.yaml
View File

@ -61,16 +61,6 @@ punchy: true
# path to a network adjacent nebula node.
#local_range: "172.16.0.0/24"
# Handshake mac is an optional network-wide handshake authentication step that is used to prevent nebula from
# responding to handshakes from nodes not in possession of the shared secret. This is primarily used to prevent
# detection of nebula nodes when someone is scanning a network.
#handshake_mac:
#key: "DONOTUSETHISKEY"
# You can define multiple accepted keys
#accepted_keys:
#- "DONOTUSETHISKEY"
#- "dontusethiseither"
# sshd can expose informational and administrative functions via ssh this is a
#sshd:
# Toggles the feature

51
handshake.go
View File

@ -1,12 +1,5 @@
package nebula
import (
"crypto/hmac"
"crypto/sha256"
"errors"
"github.com/golang/protobuf/proto"
)
const (
handshakeIXPSK0 = 0
handshakeXXPSK0 = 1
@ -36,47 +29,3 @@ func HandleIncomingHandshake(f *Interface, addr *udpAddr, packet []byte, h *Head
f.handshakeManager.DeleteVpnIP(newHostinfo.hostId)
}
}
func HandshakeBytesWithMAC(details *NebulaHandshakeDetails, key []byte) ([]byte, error) {
mac := hmac.New(sha256.New, key)
b, err := proto.Marshal(details)
if err != nil {
return nil, errors.New("Unable to marshal nebula handshake")
}
mac.Write(b)
sum := mac.Sum(nil)
hs := &NebulaHandshake{
Details: details,
Hmac: sum,
}
hsBytes, err := proto.Marshal(hs)
if err != nil {
l.Debugln("failed to generate NebulaHandshake protobuf", err)
}
return hsBytes, nil
}
func (hs *NebulaHandshake) CheckHandshakeMAC(keys [][]byte) bool {
b, err := proto.Marshal(hs.Details)
if err != nil {
return false
}
for _, k := range keys {
mac := hmac.New(sha256.New, k)
mac.Write(b)
expectedMAC := mac.Sum(nil)
if hmac.Equal(hs.Hmac, expectedMAC) {
return true
}
}
//l.Debugln(hs.Hmac, expectedMAC)
return false
}

7
handshake_ix.go
View File

@ -41,13 +41,13 @@ func ixHandshakeStage0(f *Interface, vpnIp uint32, hostinfo *HostInfo) {
Cert: ci.certState.rawCertificateNoKey,
}
hsBytes := []byte{}
hs := &NebulaHandshake{
Details: hsProto,
Hmac: nil,
}
hsBytes, err = proto.Marshal(hs)
hsBytes, err := proto.Marshal(hs)
//hsBytes, err := HandshakeBytesWithMAC(hsProto, f.handshakeMACKey)
if err != nil {
l.WithError(err).WithField("vpnIp", IntIp(vpnIp)).
WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).Error("Failed to marshal handshake message")
@ -151,7 +151,6 @@ func ixHandshakeStage1(f *Interface, addr *udpAddr, hostinfo *HostInfo, packet [
hostinfo.remoteIndexId = hs.Details.InitiatorIndex
hs.Details.ResponderIndex = myIndex
hs.Details.Cert = ci.certState.rawCertificateNoKey
hs.Hmac = nil
hsBytes, err := proto.Marshal(hs)
if err != nil {

55
interface.go
View File

@ -1,15 +1,11 @@
package nebula
import (
"crypto/sha256"
"errors"
"fmt"
"io"
"os"
"time"
"github.com/rcrowley/go-metrics"
"golang.org/x/crypto/hkdf"
)
const mtu = 9001
@ -26,8 +22,6 @@ type InterfaceConfig struct {
lightHouse *LightHouse
checkInterval int
pendingDeletionInterval int
handshakeMACKey string
handshakeAcceptedMACKeys []string
DropLocalBroadcast bool
DropMulticast bool
UDPBatchSize int
@ -45,8 +39,6 @@ type Interface struct {
serveDns bool
createTime time.Time
lightHouse *LightHouse
handshakeMACKey []byte
handshakeAcceptedMACKeys [][]byte
localBroadcast uint32
dropLocalBroadcast bool
dropMulticast bool
@ -72,37 +64,6 @@ func NewInterface(c *InterfaceConfig) (*Interface, error) {
return nil, errors.New("no firewall rules")
}
// Use KDF to make this useful
hmacKey, err := sha256KdfFromString(c.handshakeMACKey)
if err != nil {
l.Debugln(err)
}
allowedMacs := make([][]byte, 0)
//allowedMacs = append(allowedMacs, mac)
if len(c.handshakeAcceptedMACKeys) > 0 {
for _, k := range c.handshakeAcceptedMACKeys {
// Use KDF to make these useful too
hmacKey, err := sha256KdfFromString(k)
if err != nil {
l.Debugln(err)
}
allowedMacs = append(allowedMacs, hmacKey)
}
} else {
if len(c.handshakeMACKey) > 0 {
l.Warnln("You have set an outgoing MAC but do not accept any incoming. This is probably not what you want.")
} else {
// This else is a fallback if we have not set any mac keys at all
hmacKey, err := sha256KdfFromString("")
if err != nil {
l.Debugln(err)
}
allowedMacs = append(allowedMacs, hmacKey)
}
}
ifce := &Interface{
hostMap: c.HostMap,
outside: c.Outside,
@ -114,8 +75,6 @@ func NewInterface(c *InterfaceConfig) (*Interface, error) {
handshakeManager: c.HandshakeManager,
createTime: time.Now(),
lightHouse: c.lightHouse,
handshakeMACKey: hmacKey,
handshakeAcceptedMACKeys: allowedMacs,
localBroadcast: ip2int(c.certState.certificate.Details.Ips[0].IP) | ^ip2int(c.certState.certificate.Details.Ips[0].Mask),
dropLocalBroadcast: c.DropLocalBroadcast,
dropMulticast: c.DropMulticast,
@ -261,17 +220,3 @@ func (f *Interface) emitStats(i time.Duration) {
f.handshakeManager.EmitStats()
}
}
func sha256KdfFromString(secret string) ([]byte, error) {
// Use KDF to make this useful
mac := []byte(secret)
hmacKey := make([]byte, sha256.BlockSize)
hash := sha256.New
hkdfer := hkdf.New(hash, []byte(mac), nil, nil)
n, err := io.ReadFull(hkdfer, hmacKey)
if n != len(hmacKey) || err != nil {
l.Errorln("KDF Failed!")
return nil, fmt.Errorf("%s", err)
}
return hmacKey, nil
}

9
main.go
View File

@ -12,8 +12,8 @@ import (
"time"
"github.com/sirupsen/logrus"
"gopkg.in/yaml.v2"
"github.com/slackhq/nebula/sshd"
"gopkg.in/yaml.v2"
)
var l = logrus.New()
@ -238,8 +238,9 @@ func Main(configPath string, configTest bool, buildVersion string) {
handshakeManager := NewHandshakeManager(tunCidr, preferredRanges, hostMap, lightHouse, udpServer)
handshakeMACKey := config.GetString("handshake_mac.key", "")
handshakeAcceptedMACKeys := config.GetStringSlice("handshake_mac.accepted_keys", []string{})
//TODO: These will be reused for psk
//handshakeMACKey := config.GetString("handshake_mac.key", "")
//handshakeAcceptedMACKeys := config.GetStringSlice("handshake_mac.accepted_keys", []string{})
checkInterval := config.GetInt("timers.connection_alive_interval", 5)
pendingDeletionInterval := config.GetInt("timers.pending_deletion_interval", 10)
@ -255,8 +256,6 @@ func Main(configPath string, configTest bool, buildVersion string) {
lightHouse: lightHouse,
checkInterval: checkInterval,
pendingDeletionInterval: pendingDeletionInterval,
handshakeMACKey: handshakeMACKey,
handshakeAcceptedMACKeys: handshakeAcceptedMACKeys,
DropLocalBroadcast: config.GetBool("tun.drop_local_broadcast", false),
DropMulticast: config.GetBool("tun.drop_multicast", false),
UDPBatchSize: config.GetInt("listen.batch", 64),