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p2p/discover, p2p/discv5: prevent relay of invalid IPs and low ports

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The discovery DHT contains a number of hosts with LAN and loopback IPs.
These get relayed because some implementations do not perform any checks
on the IP.

go-ethereum already prevented relay in most cases because it verifies
that the host actually exists before adding it to the local table. But
this verification causes other issues. We have received several reports
where people's VPSs got shut down by hosting providers because sending
packets to random LAN hosts is indistinguishable from a slow port scan.

The new check prevents sending random packets to LAN by discarding LAN
IPs sent by Internet hosts (and loopback IPs from LAN and Internet
hosts). The new check also blacklists almost all currently registered
special-purpose networks assigned by IANA to avoid inciting random
responses from services in the LAN.

As another precaution against abuse of the DHT, ports below 1024 are now
considered invalid.
This commit is contained in:
Felix Lange
2016-11-21 18:11:54 +01:00
parent ba2884f343
commit a98d1d67d6
6 changed files with 56 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
p2p/discv5/net_test.go
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@ -40,7 +40,7 @@ func TestNetwork_Lookup(t *testing.T) {
// t.Fatalf("lookup on empty table returned %d results: %#v", len(results), results)
// }
// seed table with initial node (otherwise lookup will terminate immediately)
seeds := []*Node{NewNode(lookupTestnet.dists[256][0], net.IP{}, 256, 999)}
seeds := []*Node{NewNode(lookupTestnet.dists[256][0], net.IP{10, 0, 2, 99}, lowPort+256, 999)}
if err := network.SetFallbackNodes(seeds); err != nil {
t.Fatal(err)
}
@ -272,13 +272,13 @@ func (tn *preminedTestnet) sendFindnode(to *Node, target NodeID) {
func (tn *preminedTestnet) sendFindnodeHash(to *Node, target common.Hash) {
// current log distance is encoded in port number
// fmt.Println("findnode query at dist", toaddr.Port)
if to.UDP == 0 {
panic("query to node at distance 0")
if to.UDP <= lowPort {
panic("query to node at or below distance 0")
}
next := to.UDP - 1
var result []rpcNode
for i, id := range tn.dists[to.UDP] {
result = append(result, nodeToRPC(NewNode(id, net.ParseIP("127.0.0.1"), next, uint16(i)+1)))
for i, id := range tn.dists[to.UDP-lowPort] {
result = append(result, nodeToRPC(NewNode(id, net.ParseIP("10.0.2.99"), next, uint16(i)+1+lowPort)))
}
injectResponse(tn.net, to, neighborsPacket, &neighbors{Nodes: result})
}
@ -296,14 +296,14 @@ func (tn *preminedTestnet) send(to *Node, ptype nodeEvent, data interface{}) (ha
// ignored
case findnodeHashPacket:
// current log distance is encoded in port number
// fmt.Println("findnode query at dist", toaddr.Port)
if to.UDP == 0 {
panic("query to node at distance 0")
// fmt.Println("findnode query at dist", toaddr.Port-lowPort)
if to.UDP <= lowPort {
panic("query to node at or below distance 0")
}
next := to.UDP - 1
var result []rpcNode
for i, id := range tn.dists[to.UDP] {
result = append(result, nodeToRPC(NewNode(id, net.ParseIP("127.0.0.1"), next, uint16(i)+1)))
for i, id := range tn.dists[to.UDP-lowPort] {
result = append(result, nodeToRPC(NewNode(id, net.ParseIP("10.0.2.99"), next, uint16(i)+1+lowPort)))
}
injectResponse(tn.net, to, neighborsPacket, &neighbors{Nodes: result})
default:
@ -328,8 +328,11 @@ func (tn *preminedTestnet) sendTopicRegister(to *Node, topics []Topic, idx int,
panic("sendTopicRegister called")
}
func (*preminedTestnet) Close() {}
func (*preminedTestnet) localAddr() *net.UDPAddr { return new(net.UDPAddr) }
func (*preminedTestnet) Close() {}
func (*preminedTestnet) localAddr() *net.UDPAddr {
return &net.UDPAddr{IP: net.ParseIP("10.0.1.1"), Port: 40000}
}
// mine generates a testnet struct literal with nodes at
// various distances to the given target.