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Ignore expected IVs that arrive by the wrong transport.

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This prevents an attacker from replaying connections to test whether a
transport endpoint has the same owner as an endpoint on another
transport (eg probing a Bluetooth device to see whether it has the
same owner as a given internet host).
This commit is contained in:
akwizgran
2011-11-17 09:24:28 +00:00
parent 13ebd369e2
commit 66d973bcdd
5 changed files with 44 additions and 31 deletions
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4
api/net/sf/briar/api/transport/ConnectionRecogniser.java
View File

@@ -1,6 +1,7 @@
package net.sf.briar.api.transport; package net.sf.briar.api.transport;
import net.sf.briar.api.db.DbException; import net.sf.briar.api.db.DbException;
import net.sf.briar.api.protocol.TransportId;
/** /**
* Maintains the connection reordering windows and decides whether incoming * Maintains the connection reordering windows and decides whether incoming
@@ -12,5 +13,6 @@ public interface ConnectionRecogniser {
* Returns the connection's context if the connection should be accepted, * Returns the connection's context if the connection should be accepted,
* or null if the connection should be rejected. * or null if the connection should be rejected.
*/ */
ConnectionContext acceptConnection(byte[] encryptedIv) throws DbException; ConnectionContext acceptConnection(TransportId t, byte[] encryptedIv)
throws DbException;
} }

4
components/net/sf/briar/transport/ConnectionDispatcherImpl.java
View File

@@ -52,7 +52,7 @@ public class ConnectionDispatcherImpl implements ConnectionDispatcher {
// Get the connection context, or null if the IV wasn't expected // Get the connection context, or null if the IV wasn't expected
ConnectionContext ctx; ConnectionContext ctx;
try { try {
ctx = recogniser.acceptConnection(encryptedIv); ctx = recogniser.acceptConnection(t, encryptedIv);
} catch(DbException e) { } catch(DbException e) {
if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.getMessage()); if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.getMessage());
r.dispose(false); r.dispose(false);
@@ -95,7 +95,7 @@ public class ConnectionDispatcherImpl implements ConnectionDispatcher {
// Get the connection context, or null if the IV wasn't expected // Get the connection context, or null if the IV wasn't expected
ConnectionContext ctx; ConnectionContext ctx;
try { try {
ctx = recogniser.acceptConnection(encryptedIv); ctx = recogniser.acceptConnection(t, encryptedIv);
} catch(DbException e) { } catch(DbException e) {
if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.getMessage()); if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.getMessage());
s.dispose(false); s.dispose(false);

49
components/net/sf/briar/transport/ConnectionRecogniserImpl.java
View File

@@ -87,20 +87,20 @@ DatabaseListener {
TransportIndex i = db.getRemoteIndex(c, t); TransportIndex i = db.getRemoteIndex(c, t);
if(i != null) { if(i != null) {
ConnectionWindow w = db.getConnectionWindow(c, i); ConnectionWindow w = db.getConnectionWindow(c, i);
calculateIvs(c, i, w); calculateIvs(c, t, i, w);
} }
} }
} }
private synchronized void calculateIvs(ContactId c, TransportIndex i, private synchronized void calculateIvs(ContactId c, TransportId t,
ConnectionWindow w) throws DbException { TransportIndex i, ConnectionWindow w) throws DbException {
for(Entry<Long, byte[]> e : w.getUnseen().entrySet()) { for(Entry<Long, byte[]> e : w.getUnseen().entrySet()) {
long connection = e.getKey(); long connection = e.getKey();
byte[] secret = e.getValue(); byte[] secret = e.getValue();
ErasableKey ivKey = crypto.deriveIvKey(secret, true); ErasableKey ivKey = crypto.deriveIvKey(secret, true);
Bytes iv = new Bytes(encryptIv(i, connection, ivKey)); Bytes iv = new Bytes(encryptIv(i, connection, ivKey));
ivKey.erase(); ivKey.erase();
expected.put(iv, new Context(c, i, connection, w)); expected.put(iv, new Context(c, t, i, connection, w));
} }
} }
@@ -125,17 +125,24 @@ DatabaseListener {
} }
} }
public synchronized ConnectionContext acceptConnection(byte[] encryptedIv) public synchronized ConnectionContext acceptConnection(TransportId t,
throws DbException { byte[] encryptedIv) throws DbException {
if(encryptedIv.length != IV_LENGTH) if(encryptedIv.length != IV_LENGTH)
throw new IllegalArgumentException(); throw new IllegalArgumentException();
if(!initialised) initialise(); if(!initialised) initialise();
Context ctx = expected.remove(new Bytes(encryptedIv)); Bytes b = new Bytes(encryptedIv);
if(ctx == null) return null; // The IV was not expected Context ctx = expected.get(b);
// If the IV was not expected by this transport, reject the connection
if(ctx == null || !ctx.transportId.equals(t)) return null;
expected.remove(b);
ContactId c = ctx.contactId;
TransportIndex i = ctx.transportIndex;
long connection = ctx.connection;
ConnectionWindow w = ctx.window;
// Get the secret and update the connection window // Get the secret and update the connection window
byte[] secret = ctx.window.setSeen(ctx.connection); byte[] secret = w.setSeen(connection);
try { try {
db.setConnectionWindow(ctx.contactId, ctx.index, ctx.window); db.setConnectionWindow(c, i, w);
} catch(NoSuchContactException e) { } catch(NoSuchContactException e) {
// The contact was removed - clean up when we get the event // The contact was removed - clean up when we get the event
} }
@@ -143,12 +150,11 @@ DatabaseListener {
Iterator<Context> it = expected.values().iterator(); Iterator<Context> it = expected.values().iterator();
while(it.hasNext()) { while(it.hasNext()) {
Context ctx1 = it.next(); Context ctx1 = it.next();
if(ctx1.contactId.equals(ctx.contactId) if(ctx1.contactId.equals(c) && ctx1.transportIndex.equals(i))
&& ctx1.index.equals(ctx.index)) it.remove(); it.remove();
} }
calculateIvs(ctx.contactId, ctx.index, ctx.window); calculateIvs(c, t, i, w);
return new ConnectionContextImpl(ctx.contactId, ctx.index, return new ConnectionContextImpl(c, i, connection, secret);
ctx.connection, secret);
} }
public void eventOccurred(DatabaseEvent e) { public void eventOccurred(DatabaseEvent e) {
@@ -195,7 +201,7 @@ DatabaseListener {
TransportIndex i = db.getRemoteIndex(c, t); TransportIndex i = db.getRemoteIndex(c, t);
if(i != null) { if(i != null) {
ConnectionWindow w = db.getConnectionWindow(c, i); ConnectionWindow w = db.getConnectionWindow(c, i);
calculateIvs(c, i, w); calculateIvs(c, t, i, w);
} }
} catch(NoSuchContactException e) { } catch(NoSuchContactException e) {
// The contact was removed - clean up when we get the event // The contact was removed - clean up when we get the event
@@ -206,14 +212,17 @@ DatabaseListener {
private static class Context { private static class Context {
private final ContactId contactId; private final ContactId contactId;
private final TransportIndex index; private final TransportId transportId;
private final TransportIndex transportIndex;
private final long connection; private final long connection;
private final ConnectionWindow window; private final ConnectionWindow window;
private Context(ContactId contactId, TransportIndex index, private Context(ContactId contactId, TransportId transportId,
long connection, ConnectionWindow window) { TransportIndex transportIndex, long connection,
ConnectionWindow window) {
this.contactId = contactId; this.contactId = contactId;
this.index = index; this.transportId = transportId;
this.transportIndex = transportIndex;
this.connection = connection; this.connection = connection;
this.window = window; this.window = window;
} }

16
test/net/sf/briar/transport/ConnectionRecogniserImplTest.java
View File

@@ -74,7 +74,7 @@ public class ConnectionRecogniserImplTest extends TestCase {
}}); }});
final ConnectionRecogniserImpl c = final ConnectionRecogniserImpl c =
new ConnectionRecogniserImpl(crypto, db); new ConnectionRecogniserImpl(crypto, db);
assertNull(c.acceptConnection(new byte[IV_LENGTH])); assertNull(c.acceptConnection(transportId, new byte[IV_LENGTH]));
context.assertIsSatisfied(); context.assertIsSatisfied();
} }
@@ -111,20 +111,22 @@ public class ConnectionRecogniserImplTest extends TestCase {
}}); }});
final ConnectionRecogniserImpl c = final ConnectionRecogniserImpl c =
new ConnectionRecogniserImpl(crypto, db); new ConnectionRecogniserImpl(crypto, db);
// First time - the IV should be expected // The IV should not be expected by the wrong transport
ConnectionContext ctx = c.acceptConnection(encryptedIv); TransportId wrong = new TransportId(TestUtils.getRandomId());
assertNull(c.acceptConnection(wrong, encryptedIv));
// The IV should be expected by the right transport
ConnectionContext ctx = c.acceptConnection(transportId, encryptedIv);
assertNotNull(ctx); assertNotNull(ctx);
assertEquals(contactId, ctx.getContactId()); assertEquals(contactId, ctx.getContactId());
assertEquals(remoteIndex, ctx.getTransportIndex()); assertEquals(remoteIndex, ctx.getTransportIndex());
assertEquals(3L, ctx.getConnectionNumber()); assertEquals(3L, ctx.getConnectionNumber());
// Second time - the IV should no longer be expected // The IV should no longer be expected
assertNull(c.acceptConnection(encryptedIv)); assertNull(c.acceptConnection(transportId, encryptedIv));
// The window should have advanced // The window should have advanced
Map<Long, byte[]> unseen = connectionWindow.getUnseen(); Map<Long, byte[]> unseen = connectionWindow.getUnseen();
assertEquals(19, unseen.size()); assertEquals(19, unseen.size());
for(int i = 0; i < 19; i++) { for(int i = 0; i < 19; i++) {
if(i == 3) continue; assertEquals(i != 3, unseen.containsKey(Long.valueOf(i)));
assertTrue(unseen.containsKey(Long.valueOf(i)));
} }
context.assertIsSatisfied(); context.assertIsSatisfied();
} }

2
test/net/sf/briar/transport/batch/BatchConnectionReadWriteTest.java
View File

@@ -159,7 +159,7 @@ public class BatchConnectionReadWriteTest extends TestCase {
byte[] encryptedIv = new byte[IV_LENGTH]; byte[] encryptedIv = new byte[IV_LENGTH];
int read = in.read(encryptedIv); int read = in.read(encryptedIv);
assertEquals(encryptedIv.length, read); assertEquals(encryptedIv.length, read);
ConnectionContext ctx = rec.acceptConnection(encryptedIv); ConnectionContext ctx = rec.acceptConnection(transportId, encryptedIv);
assertNotNull(ctx); assertNotNull(ctx);
assertEquals(contactId, ctx.getContactId()); assertEquals(contactId, ctx.getContactId());
assertEquals(transportIndex, ctx.getTransportIndex()); assertEquals(transportIndex, ctx.getTransportIndex());