From e9750fb58d7da727bab0628959795d619e50502e Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Mon, 23 Mar 2015 18:04:40 +0300
Subject: [PATCH] Zero handshake and peer states after their usage

Signed-off-by: Sergey Matveev <stargrave@stargrave.org>
---
 cmd/govpn-client/main.go |  2 ++
 cmd/govpn-server/main.go |  4 ++++
 common.go                |  7 +++++++
 handshake.go             | 19 +++++++++++++++++++
 transport.go             | 10 ++++++++++
 5 files changed, 42 insertions(+)

diff --git a/cmd/govpn-client/main.go b/cmd/govpn-client/main.go
index f4a29eb..82a89a6 100644
--- a/cmd/govpn-client/main.go
+++ b/cmd/govpn-client/main.go
@@ -93,6 +93,7 @@ func main() {
 MainCycle:
 	for {
 		if peer != nil && peer.Bytes > govpn.MaxBytesPerKey {
+			peer.Zero()
 			peer = nil
 			handshake = govpn.HandshakeStart(conn, remote, id, key)
 			log.Println("Rehandshaking")
@@ -132,6 +133,7 @@ MainCycle:
 						firstUpCall = false
 					}
 					peer = p
+					handshake.Zero()
 					handshake = nil
 				}
 				udpReady <- struct{}{}
diff --git a/cmd/govpn-server/main.go b/cmd/govpn-server/main.go
index 4fa5c96..1ce5a37 100644
--- a/cmd/govpn-server/main.go
+++ b/cmd/govpn-server/main.go
@@ -129,6 +129,7 @@ MainCycle:
 			for addr, hs := range states {
 				if hs.LastPing.Add(timeout).Before(now) {
 					log.Println("Deleting handshake state", addr)
+					hs.Zero()
 					delete(states, addr)
 				}
 			}
@@ -143,6 +144,7 @@ MainCycle:
 					)
 					go govpn.ScriptCall(downPath, state.tap.Name)
 					state.terminate <- struct{}{}
+					state.peer.Zero()
 				}
 			}
 		case peerReady = <-peerReadySink:
@@ -152,6 +154,7 @@ MainCycle:
 				}
 				delete(peers, addr)
 				state.terminate <- struct{}{}
+				state.peer.Zero()
 				break
 			}
 			addr = peerReady.peer.Addr.String()
@@ -160,6 +163,7 @@ MainCycle:
 				continue
 			}
 			peers[addr] = state
+			states[addr].Zero()
 			delete(states, addr)
 			log.Println("Registered interface", peerReady.iface, "with peer", peer)
 			go func(state *PeerState) {
diff --git a/common.go b/common.go
index b42673c..545274f 100644
--- a/common.go
+++ b/common.go
@@ -74,3 +74,10 @@ func KeyRead(path string) *[KeySize]byte {
 	copy(key[:], keyDecoded)
 	return key
 }
+
+// Zero each byte
+func sliceZero(data []byte) {
+	for i := 0; i < len(data); i++ {
+		data[i] = '\x00'
+	}
+}
diff --git a/handshake.go b/handshake.go
index c458f5d..44f9a29 100644
--- a/handshake.go
+++ b/handshake.go
@@ -69,6 +69,25 @@ func IsValidHandshakePkt(pkt []byte) bool {
 	return true
 }
 
+// Zero handshake's memory state
+func (h *Handshake) Zero() {
+	sliceZero(h.rNonce[:])
+	sliceZero(h.dhPriv[:])
+	sliceZero(h.key[:])
+	if h.rServer != nil {
+		sliceZero(h.rServer[:])
+	}
+	if h.rClient != nil {
+		sliceZero(h.rClient[:])
+	}
+	if h.sServer != nil {
+		sliceZero(h.sServer[:])
+	}
+	if h.sClient != nil {
+		sliceZero(h.sClient[:])
+	}
+}
+
 func (h *Handshake) rNonceNext() []byte {
 	nonce := make([]byte, 8)
 	nonceCurrent, _ := binary.Uvarint(h.rNonce[:])
diff --git a/transport.go b/transport.go
index d72fcc1..31bfe7f 100644
--- a/transport.go
+++ b/transport.go
@@ -67,6 +67,16 @@ func (p *Peer) String() string {
 	return p.Id.String() + ":" + p.Addr.String()
 }
 
+// Zero peer's memory state
+func (p *Peer) Zero() {
+	sliceZero(p.Key[:])
+	sliceZero(p.tag[:])
+	sliceZero(p.keyAuth[:])
+	sliceZero(p.buf)
+	sliceZero(p.frame)
+	sliceZero(p.nonce)
+}
+
 var (
 	HeartbeatMark   = []byte("\x00\x00\x00HEARTBEAT")
 	Emptiness       = make([]byte, KeySize)
-- 
2.48.1