yggdrasil-network/yggdrasil-go
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Protect session nonces with mutexes, modify sent/received bytes atomically

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This commit is contained in:
Neil Alexander 2019-04-19 20:10:41 +01:00
parent ade684beff
commit e3eadba4b7
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GPG key ID: A02A2019A2BB0944
2 changed files with 25 additions and 10 deletions
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28
src/yggdrasil/session.go
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@ -29,9 +29,10 @@ type sessionInfo struct {
theirHandle crypto.Handle
myHandle crypto.Handle
theirNonce crypto.BoxNonce
theirNonceMutex sync.RWMutex // protects the above
theirNonceMask uint64
theirNonceMutex sync.Mutex // protects the above
myNonce crypto.BoxNonce
myNonceMutex sync.RWMutex // protects the above
myNonceMutex sync.Mutex // protects the above
theirMTU uint16
myMTU uint16
wasMTUFixed bool // Was the MTU fixed by a receive error?
@ -42,7 +43,6 @@ type sessionInfo struct {
send chan []byte
recv chan *wire_trafficPacket
closed chan interface{}
nonceMask uint64
tstamp int64 // tstamp from their last session ping, replay attack mitigation
tstampMutex int64 // protects the above
mtuTime time.Time // time myMTU was last changed
@ -79,8 +79,10 @@ func (s *sessionInfo) update(p *sessionPing) bool {
s.theirSesPub = p.SendSesPub
s.theirHandle = p.Handle
s.sharedSesKey = *crypto.GetSharedKey(&s.mySesPriv, &s.theirSesPub)
s.theirNonceMutex.Lock()
s.theirNonce = crypto.BoxNonce{}
s.nonceMask = 0
s.theirNonceMask = 0
s.theirNonceMutex.Unlock()
}
if p.MTU >= 1280 || p.MTU == 0 {
s.theirMTU = p.MTU
@ -270,6 +272,10 @@ func (ss *sessions) createSession(theirPermKey *crypto.BoxPubKey) *sessionInfo {
return nil
}
sinfo := sessionInfo{}
sinfo.myNonceMutex.Lock()
sinfo.theirNonceMutex.Lock()
defer sinfo.myNonceMutex.Unlock()
defer sinfo.theirNonceMutex.Unlock()
sinfo.core = ss.core
sinfo.reconfigure = make(chan chan error, 1)
sinfo.theirPermPub = *theirPermKey
@ -389,7 +395,9 @@ func (ss *sessions) getPing(sinfo *sessionInfo) sessionPing {
Coords: coords,
MTU: sinfo.myMTU,
}
sinfo.myNonceMutex.Lock()
sinfo.myNonce.Increment()
sinfo.myNonceMutex.Unlock()
return ref
}
@ -493,26 +501,30 @@ func (sinfo *sessionInfo) getMTU() uint16 {
// Checks if a packet's nonce is recent enough to fall within the window of allowed packets, and not already received.
func (sinfo *sessionInfo) nonceIsOK(theirNonce *crypto.BoxNonce) bool {
// The bitmask is to allow for some non-duplicate out-of-order packets
sinfo.theirNonceMutex.Lock()
defer sinfo.theirNonceMutex.Unlock()
diff := theirNonce.Minus(&sinfo.theirNonce)
if diff > 0 {
return true
}
return ^sinfo.nonceMask&(0x01<<uint64(-diff)) != 0
return ^sinfo.theirNonceMask&(0x01<<uint64(-diff)) != 0
}
// Updates the nonce mask by (possibly) shifting the bitmask and setting the bit corresponding to this nonce to 1, and then updating the most recent nonce
func (sinfo *sessionInfo) updateNonce(theirNonce *crypto.BoxNonce) {
sinfo.theirNonceMutex.Lock()
defer sinfo.theirNonceMutex.Unlock()
// Shift nonce mask if needed
// Set bit
diff := theirNonce.Minus(&sinfo.theirNonce)
if diff > 0 {
// This nonce is newer, so shift the window before setting the bit, and update theirNonce in the session info.
sinfo.nonceMask <<= uint64(diff)
sinfo.nonceMask &= 0x01
sinfo.theirNonceMask <<= uint64(diff)
sinfo.theirNonceMask &= 0x01
sinfo.theirNonce = *theirNonce
} else {
// This nonce is older, so set the bit but do not shift the window.
sinfo.nonceMask &= 0x01 << uint64(-diff)
sinfo.theirNonceMask &= 0x01 << uint64(-diff)
}
}