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

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
p2p/discover/table_test.go
View File

@ -146,6 +146,7 @@ func fillBucket(tab *Table, ld int) (last *Node) {
func nodeAtDistance(base common.Hash, ld int) (n *Node) {
n = new(Node)
n.sha = hashAtDistance(base, ld)
n.IP = net.IP{10, 0, 2, byte(ld)}
copy(n.ID[:], n.sha[:]) // ensure the node still has a unique ID
return n
}

20
p2p/discover/udp.go
View File

@ -29,6 +29,7 @@ import (
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/p2p/nat"
"github.com/ethereum/go-ethereum/p2p/netutil"
"github.com/ethereum/go-ethereum/rlp"
)
@ -126,8 +127,13 @@ func makeEndpoint(addr *net.UDPAddr, tcpPort uint16) rpcEndpoint {
return rpcEndpoint{IP: ip, UDP: uint16(addr.Port), TCP: tcpPort}
}
func nodeFromRPC(rn rpcNode) (*Node, error) {
// TODO: don't accept localhost, LAN addresses from internet hosts
func nodeFromRPC(sender *net.UDPAddr, rn rpcNode) (*Node, error) {
if rn.UDP <= 1024 {
return nil, errors.New("low port")
}
if err := netutil.CheckRelayIP(sender.IP, rn.IP); err != nil {
return nil, err
}
n := NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP)
err := n.validateComplete()
return n, err
@ -281,9 +287,12 @@ func (t *udp) findnode(toid NodeID, toaddr *net.UDPAddr, target NodeID) ([]*Node
reply := r.(*neighbors)
for _, rn := range reply.Nodes {
nreceived++
if n, err := nodeFromRPC(rn); err == nil {
nodes = append(nodes, n)
n, err := nodeFromRPC(toaddr, rn)
if err != nil {
glog.V(logger.Detail).Infof("invalid neighbor node (%v) from %v: %v", rn.IP, toaddr, err)
continue
}
nodes = append(nodes, n)
}
return nreceived >= bucketSize
})
@ -595,6 +604,9 @@ func (req *findnode) handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte
// Send neighbors in chunks with at most maxNeighbors per packet
// to stay below the 1280 byte limit.
for i, n := range closest {
if netutil.CheckRelayIP(from.IP, n.IP) != nil {
continue
}
p.Nodes = append(p.Nodes, nodeToRPC(n))
if len(p.Nodes) == maxNeighbors || i == len(closest)-1 {
t.send(from, neighborsPacket, p)

7
p2p/discover/udp_test.go
View File

@ -68,7 +68,7 @@ func newUDPTest(t *testing.T) *udpTest {
pipe: newpipe(),
localkey: newkey(),
remotekey: newkey(),
remoteaddr: &net.UDPAddr{IP: net.IP{1, 2, 3, 4}, Port: 30303},
remoteaddr: &net.UDPAddr{IP: net.IP{10, 0, 1, 99}, Port: 30303},
}
test.table, test.udp, _ = newUDP(test.localkey, test.pipe, nil, "")
return test
@ -312,8 +312,9 @@ func TestUDP_findnodeMultiReply(t *testing.T) {
// check that the sent neighbors are all returned by findnode
select {
case result := <-resultc:
if !reflect.DeepEqual(result, list) {
t.Errorf("neighbors mismatch:\n got: %v\n want: %v", result, list)
want := append(list[:2], list[3:]...)
if !reflect.DeepEqual(result, want) {
t.Errorf("neighbors mismatch:\n got: %v\n want: %v", result, want)
}
case err := <-errc:
t.Errorf("findnode error: %v", err)

19
p2p/discv5/net.go
View File

@ -45,6 +45,7 @@ const (
bucketRefreshInterval = 1 * time.Minute
seedCount = 30
seedMaxAge = 5 * 24 * time.Hour
lowPort = 1024
)
const testTopic = "foo"
@ -684,16 +685,19 @@ func (net *Network) internNodeFromDB(dbn *Node) *Node {
return n
}
func (net *Network) internNodeFromNeighbours(rn rpcNode) (n *Node, err error) {
func (net *Network) internNodeFromNeighbours(sender *net.UDPAddr, rn rpcNode) (n *Node, err error) {
if rn.ID == net.tab.self.ID {
return nil, errors.New("is self")
}
if rn.UDP <= lowPort {
return nil, errors.New("low port")
}
n = net.nodes[rn.ID]
if n == nil {
// We haven't seen this node before.
n, err = nodeFromRPC(rn)
n.state = unknown
n, err = nodeFromRPC(sender, rn)
if err == nil {
n.state = unknown
net.nodes[n.ID] = n
}
return n, err
@ -1095,7 +1099,7 @@ func (net *Network) handleQueryEvent(n *Node, ev nodeEvent, pkt *ingressPacket)
net.conn.sendNeighbours(n, results)
return n.state, nil
case neighborsPacket:
err := net.handleNeighboursPacket(n, pkt.data.(*neighbors))
err := net.handleNeighboursPacket(n, pkt)
return n.state, err
case neighboursTimeout:
if n.pendingNeighbours != nil {
@ -1182,17 +1186,18 @@ func rlpHash(x interface{}) (h common.Hash) {
return h
}
func (net *Network) handleNeighboursPacket(n *Node, req *neighbors) error {
func (net *Network) handleNeighboursPacket(n *Node, pkt *ingressPacket) error {
if n.pendingNeighbours == nil {
return errNoQuery
}
net.abortTimedEvent(n, neighboursTimeout)
req := pkt.data.(*neighbors)
nodes := make([]*Node, len(req.Nodes))
for i, rn := range req.Nodes {
nn, err := net.internNodeFromNeighbours(rn)
nn, err := net.internNodeFromNeighbours(pkt.remoteAddr, rn)
if err != nil {
glog.V(logger.Debug).Infof("invalid neighbour from %x: %v", n.ID[:8], err)
glog.V(logger.Debug).Infof("invalid neighbour (%v) from %x@%v: %v", rn.IP, n.ID[:8], pkt.remoteAddr, err)
continue
}
nodes[i] = nn

27
p2p/discv5/net_test.go
View File

@ -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.

10
p2p/discv5/udp.go
View File

@ -29,6 +29,7 @@ import (
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/p2p/nat"
"github.com/ethereum/go-ethereum/p2p/netutil"
"github.com/ethereum/go-ethereum/rlp"
)
@ -198,8 +199,10 @@ func (e1 rpcEndpoint) equal(e2 rpcEndpoint) bool {
return e1.UDP == e2.UDP && e1.TCP == e2.TCP && bytes.Equal(e1.IP, e2.IP)
}
func nodeFromRPC(rn rpcNode) (*Node, error) {
// TODO: don't accept localhost, LAN addresses from internet hosts
func nodeFromRPC(sender *net.UDPAddr, rn rpcNode) (*Node, error) {
if err := netutil.CheckRelayIP(sender.IP, rn.IP); err != nil {
return nil, err
}
n := NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP)
err := n.validateComplete()
return n, err
@ -327,6 +330,9 @@ func (t *udp) sendTopicNodes(remote *Node, queryHash common.Hash, nodes []*Node)
return
}
for i, result := range nodes {
if netutil.CheckRelayIP(remote.IP, result.IP) != nil {
continue
}
p.Nodes = append(p.Nodes, nodeToRPC(result))
if len(p.Nodes) == maxTopicNodes || i == len(nodes)-1 {
t.sendPacket(remote.ID, remote.addr(), byte(topicNodesPacket), p)