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swarm/pss: fix data race on HandshakeController.symKeyIndex (ethereum…
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…#19162)

* swarm/pss: fix data race on HandshakeController.symKeyIndex

The HandshakeController.symKeyIndex map was accessed concurrently.
Since insufficient test coverage the race is not detected every time.
However, running TestClientHandshake a 100 times seems to be enough to
reproduce the race.

Note: I've chosen HandshakeController.lock to protect
HandshakeController.symKeyIndex as that was already protected in a few
functions by that lock.

Additionally:
- removed unused testStore
- enabled tests in handshake_test.go as they pass
- removed code duplication by adding getSymKey()

* swarm/pss: fix a data race on HandshakeController.keyC

* swarm/pss: fix data races with on Pss.symKeyPool
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@janos @zelig
janos authored and zelig committed Feb 26, 2019
1 parent badaf43 commit 340a53a
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Showing 4 changed files with 55 additions and 48 deletions.
16 changes: 0 additions & 16 deletions swarm/pss/client/client_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@ import (
"fmt"
"math/rand"
"os"
"sync"
"testing"
"time"

Expand Down Expand Up @@ -286,18 +285,3 @@ func newServices() adapters.Services {
},
}
}

// copied from swarm/network/protocol_test_go
type testStore struct {
sync.Mutex

values map[string][]byte
}

func (t *testStore) Load(key string) ([]byte, error) {
return nil, nil
}

func (t *testStore) Save(key string, v []byte) error {
return nil
}
78 changes: 52 additions & 26 deletions swarm/pss/handshake.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,7 @@ func NewHandshakeParams() *HandshakeParams {
type HandshakeController struct {
pss *Pss
keyC map[string]chan []string // adds a channel to report when a handshake succeeds
keyCMu sync.Mutex // protects keyC map
lock sync.Mutex
symKeyRequestTimeout time.Duration
symKeyExpiryTimeout time.Duration
Expand Down Expand Up @@ -165,9 +166,9 @@ func (ctl *HandshakeController) validKeys(pubkeyid string, topic *Topic, in bool

for _, key := range *keystore {
if key.limit <= key.count {
ctl.releaseKey(*key.symKeyID, topic)
ctl.releaseKeyNoLock(*key.symKeyID, topic)
} else if !key.expiredAt.IsZero() && key.expiredAt.Before(now) {
ctl.releaseKey(*key.symKeyID, topic)
ctl.releaseKeyNoLock(*key.symKeyID, topic)
} else {
validkeys = append(validkeys, key.symKeyID)
}
Expand Down Expand Up @@ -205,15 +206,23 @@ func (ctl *HandshakeController) updateKeys(pubkeyid string, topic *Topic, in boo
limit: limit,
}
*keystore = append(*keystore, storekey)
ctl.pss.mx.Lock()
ctl.pss.symKeyPool[*storekey.symKeyID][*topic].protected = true
ctl.pss.mx.Unlock()
}
for i := 0; i < len(*keystore); i++ {
ctl.symKeyIndex[*(*keystore)[i].symKeyID] = &((*keystore)[i])
}
}

// Expire a symmetric key, making it elegible for garbage collection
func (ctl *HandshakeController) releaseKey(symkeyid string, topic *Topic) bool {
ctl.lock.Lock()
defer ctl.lock.Unlock()
return ctl.releaseKeyNoLock(symkeyid, topic)
}

// Expire a symmetric key, making it eligible for garbage collection
func (ctl *HandshakeController) releaseKeyNoLock(symkeyid string, topic *Topic) bool {
if ctl.symKeyIndex[symkeyid] == nil {
log.Debug("no symkey", "symkeyid", symkeyid)
return false
Expand Down Expand Up @@ -276,30 +285,49 @@ func (ctl *HandshakeController) clean() {
}
}

func (ctl *HandshakeController) getSymKey(symkeyid string) *handshakeKey {
ctl.lock.Lock()
defer ctl.lock.Unlock()
return ctl.symKeyIndex[symkeyid]
}

// Passed as a PssMsg handler for the topic handshake is activated on
// Handles incoming key exchange messages and
// ccunts message usage by symmetric key (expiry limit control)
// counts message usage by symmetric key (expiry limit control)
// Only returns error if key handler fails
func (ctl *HandshakeController) handler(msg []byte, p *p2p.Peer, asymmetric bool, symkeyid string) error {
if !asymmetric {
if ctl.symKeyIndex[symkeyid] != nil {
if ctl.symKeyIndex[symkeyid].count >= ctl.symKeyIndex[symkeyid].limit {
return fmt.Errorf("discarding message using expired key: %s", symkeyid)
if asymmetric {
keymsg := &handshakeMsg{}
err := rlp.DecodeBytes(msg, keymsg)
if err == nil {
err := ctl.handleKeys(symkeyid, keymsg)
if err != nil {
log.Error("handlekeys fail", "error", err)
}
ctl.symKeyIndex[symkeyid].count++
log.Trace("increment symkey recv use", "symsymkeyid", symkeyid, "count", ctl.symKeyIndex[symkeyid].count, "limit", ctl.symKeyIndex[symkeyid].limit, "receiver", common.ToHex(crypto.FromECDSAPub(ctl.pss.PublicKey())))
return err
}
return nil
}
keymsg := &handshakeMsg{}
err := rlp.DecodeBytes(msg, keymsg)
if err == nil {
err := ctl.handleKeys(symkeyid, keymsg)
if err != nil {
log.Error("handlekeys fail", "error", err)
}
return err
return ctl.registerSymKeyUse(symkeyid)
}

func (ctl *HandshakeController) registerSymKeyUse(symkeyid string) error {
ctl.lock.Lock()
defer ctl.lock.Unlock()

symKey, ok := ctl.symKeyIndex[symkeyid]
if !ok {
return nil
}

if symKey.count >= symKey.limit {
return fmt.Errorf("symetric key expired (id: %s)", symkeyid)
}
symKey.count++

receiver := common.ToHex(crypto.FromECDSAPub(ctl.pss.PublicKey()))
log.Trace("increment symkey recv use", "symsymkeyid", symkeyid, "count", symKey.count, "limit", symKey.limit, "receiver", receiver)

return nil
}

Expand Down Expand Up @@ -417,6 +445,8 @@ func (ctl *HandshakeController) sendKey(pubkeyid string, topic *Topic, keycount

// Enables callback for keys received from a key exchange request
func (ctl *HandshakeController) alertHandshake(pubkeyid string, symkeys []string) chan []string {
ctl.keyCMu.Lock()
defer ctl.keyCMu.Unlock()
if len(symkeys) > 0 {
if _, ok := ctl.keyC[pubkeyid]; ok {
ctl.keyC[pubkeyid] <- symkeys
Expand Down Expand Up @@ -519,7 +549,7 @@ func (api *HandshakeAPI) GetHandshakeKeys(pubkeyid string, topic Topic, in bool,
// Returns the amount of messages the specified symmetric key
// is still valid for under the handshake scheme
func (api *HandshakeAPI) GetHandshakeKeyCapacity(symkeyid string) (uint16, error) {
storekey := api.ctrl.symKeyIndex[symkeyid]
storekey := api.ctrl.getSymKey(symkeyid)
if storekey == nil {
return 0, fmt.Errorf("invalid symkey id %s", symkeyid)
}
Expand All @@ -529,7 +559,7 @@ func (api *HandshakeAPI) GetHandshakeKeyCapacity(symkeyid string) (uint16, error
// Returns the byte representation of the public key in ascii hex
// associated with the given symmetric key
func (api *HandshakeAPI) GetHandshakePublicKey(symkeyid string) (string, error) {
storekey := api.ctrl.symKeyIndex[symkeyid]
storekey := api.ctrl.getSymKey(symkeyid)
if storekey == nil {
return "", fmt.Errorf("invalid symkey id %s", symkeyid)
}
Expand All @@ -555,12 +585,8 @@ func (api *HandshakeAPI) ReleaseHandshakeKey(pubkeyid string, topic Topic, symke
// for message expiry control
func (api *HandshakeAPI) SendSym(symkeyid string, topic Topic, msg hexutil.Bytes) (err error) {
err = api.ctrl.pss.SendSym(symkeyid, topic, msg[:])
if api.ctrl.symKeyIndex[symkeyid] != nil {
if api.ctrl.symKeyIndex[symkeyid].count >= api.ctrl.symKeyIndex[symkeyid].limit {
return errors.New("attempted send with expired key")
}
api.ctrl.symKeyIndex[symkeyid].count++
log.Trace("increment symkey send use", "symkeyid", symkeyid, "count", api.ctrl.symKeyIndex[symkeyid].count, "limit", api.ctrl.symKeyIndex[symkeyid].limit, "receiver", common.ToHex(crypto.FromECDSAPub(api.ctrl.pss.PublicKey())))
if otherErr := api.ctrl.registerSymKeyUse(symkeyid); otherErr != nil {
return otherErr
}
return err
}
5 changes: 1 addition & 4 deletions swarm/pss/handshake_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,6 @@
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// +build foo

package pss

import (
Expand All @@ -30,7 +28,6 @@ import (
// asymmetrical key exchange between two directly connected peers
// full address, partial address (8 bytes) and empty address
func TestHandshake(t *testing.T) {
t.Skip("handshakes are not adapted to current pss core code")
t.Run("32", testHandshake)
t.Run("8", testHandshake)
t.Run("0", testHandshake)
Expand All @@ -47,7 +44,7 @@ func testHandshake(t *testing.T) {

// set up two nodes directly connected
// (we are not testing pss routing here)
clients, err := setupNetwork(2)
clients, err := setupNetwork(2, true)
if err != nil {
t.Fatal(err)
}
Expand Down
4 changes: 2 additions & 2 deletions swarm/pss/keystore.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -210,6 +210,8 @@ func (ks *Pss) processAsym(envelope *whisper.Envelope) (*whisper.ReceivedMessage
// - it is not marked as protected
// - it is not in the incoming decryption cache
func (ks *Pss) cleanKeys() (count int) {
ks.mx.Lock()
defer ks.mx.Unlock()
for keyid, peertopics := range ks.symKeyPool {
var expiredtopics []Topic
for topic, psp := range peertopics {
Expand All @@ -229,10 +231,8 @@ func (ks *Pss) cleanKeys() (count int) {
}
}
for _, topic := range expiredtopics {
ks.mx.Lock()
delete(ks.symKeyPool[keyid], topic)
log.Trace("symkey cleanup deletion", "symkeyid", keyid, "topic", topic, "val", ks.symKeyPool[keyid])
ks.mx.Unlock()
count++
}
}
Expand Down

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