safing-portmaster/service/network/state/lookup.go
2024-05-08 14:19:10 +02:00

264 lines
7.7 KiB
Go

package state
import (
"errors"
"github.com/safing/portmaster/service/network/netutils"
"github.com/safing/portmaster/service/network/packet"
"github.com/safing/portmaster/service/network/socket"
)
// - TCP
// - Outbound: Match listeners (in!), then connections (out!)
// - Inbound: Match listeners (in!), then connections (out!)
// - Clean via connections
// - UDP
// - Any connection: match specific local address or zero IP
// - In or out: save direction of first packet:
// - map[<local udp bind ip+port>]map[<remote ip+port>]{direction, lastSeen}
// - only clean if <local udp bind ip+port> is removed by OS
// - limit <remote ip+port> to 256 entries?
// - clean <remote ip+port> after 72hrs?
// - switch direction to outbound if outbound packet is seen?
// - IP: Unidentified Process
// Errors.
var (
ErrConnectionNotFound = errors.New("could not find connection in system state tables")
ErrPIDNotFound = errors.New("could not find pid for socket inode")
)
const (
lookupTries = 5
fastLookupTries = 2 // 1. current table, 2. get table with max 10ms, could be 0ms, 3. 10ms wait
)
// Lookup looks for the given connection in the system state tables and returns the PID of the associated process and whether the connection is inbound.
func Lookup(pktInfo *packet.Info, fast bool) (pid int, inbound bool, err error) {
// auto-detect version
if pktInfo.Version == 0 {
if ip := pktInfo.LocalIP().To4(); ip != nil {
pktInfo.Version = packet.IPv4
} else {
pktInfo.Version = packet.IPv6
}
}
switch {
case pktInfo.Version == packet.IPv4 && pktInfo.Protocol == packet.TCP:
return tcp4Table.lookup(pktInfo, fast)
case pktInfo.Version == packet.IPv6 && pktInfo.Protocol == packet.TCP:
return tcp6Table.lookup(pktInfo, fast)
case pktInfo.Version == packet.IPv4 && pktInfo.Protocol == packet.UDP:
return udp4Table.lookup(pktInfo, fast)
case pktInfo.Version == packet.IPv6 && pktInfo.Protocol == packet.UDP:
return udp6Table.lookup(pktInfo, fast)
default:
return socket.UndefinedProcessID, pktInfo.Inbound, errors.New("unsupported protocol for finding process")
}
}
func (table *tcpTable) lookup(pktInfo *packet.Info, fast bool) (
pid int,
inbound bool,
err error,
) {
// Prepare variables.
var (
connections []*socket.ConnectionInfo
listeners []*socket.BindInfo
dualStackConnections []*socket.ConnectionInfo
dualStackListeners []*socket.BindInfo
)
// Search for the socket until found.
for i := 1; i <= lookupTries; i++ {
// Use existing tables for first check if packet was seen after last table update.
if i == 1 && pktInfo.SeenAt.UnixNano() >= table.lastUpdateAt.Load() {
connections, listeners = table.getCurrentTables()
} else {
connections, listeners = table.updateTables()
}
// Check tables for socket.
socketInfo, inbound := findTCPSocket(pktInfo, connections, listeners)
// If there's a match, check if we have the PID and return.
if socketInfo != nil {
return CheckPID(socketInfo, inbound)
}
// DUAL-STACK
// Skip if dualStack is not enabled.
if table.dualStack == nil {
continue
}
// Use existing tables for first check if packet was seen after last table update.
if i == 1 && pktInfo.SeenAt.UnixNano() >= table.dualStack.lastUpdateAt.Load() {
dualStackConnections, dualStackListeners = table.dualStack.getCurrentTables()
} else {
dualStackConnections, dualStackListeners = table.dualStack.updateTables()
}
// Check tables for socket.
socketInfo, inbound = findTCPSocket(pktInfo, dualStackConnections, dualStackListeners)
// If there's a match, check if we have the PID and return.
if socketInfo != nil {
return CheckPID(socketInfo, inbound)
}
// Search less if we want to be fast.
if fast && i >= fastLookupTries {
break
}
}
return socket.UndefinedProcessID, pktInfo.Inbound, ErrConnectionNotFound
}
func findTCPSocket(
pktInfo *packet.Info,
connections []*socket.ConnectionInfo,
listeners []*socket.BindInfo,
) (
socketInfo socket.Info,
inbound bool,
) {
localIP := pktInfo.LocalIP()
localPort := pktInfo.LocalPort()
// always search listeners first
for _, socketInfo := range listeners {
if localPort == socketInfo.Local.Port &&
(socketInfo.ListensAny || localIP.Equal(socketInfo.Local.IP)) {
return socketInfo, true
}
}
remoteIP := pktInfo.RemoteIP()
remotePort := pktInfo.RemotePort()
// search connections
for _, socketInfo := range connections {
if localPort == socketInfo.Local.Port &&
remotePort == socketInfo.Remote.Port &&
remoteIP.Equal(socketInfo.Remote.IP) &&
localIP.Equal(socketInfo.Local.IP) {
return socketInfo, false
}
}
return nil, false
}
func (table *udpTable) lookup(pktInfo *packet.Info, fast bool) (
pid int,
inbound bool,
err error,
) {
// TODO: Currently broadcast/multicast scopes are not checked, so we might
// attribute an incoming broadcast/multicast packet to the wrong process if
// there are multiple processes listening on the same local port, but
// binding to different addresses. This highly unusual for clients.
isInboundMulticast := pktInfo.Inbound && netutils.GetIPScope(pktInfo.LocalIP()) == netutils.LocalMulticast
// Prepare variables.
var (
binds []*socket.BindInfo
dualStackBinds []*socket.BindInfo
)
// Search for the socket until found.
for i := 1; i <= lookupTries; i++ {
// Get or update tables.
if i == 1 && pktInfo.SeenAt.UnixNano() >= table.lastUpdateAt.Load() {
binds = table.getCurrentTables()
} else {
binds = table.updateTables()
}
// Check tables for socket.
socketInfo := findUDPSocket(pktInfo, binds, isInboundMulticast)
// If there's a match, do some last checks and return.
if socketInfo != nil {
// If there is no remote port, do check for the direction of the
// connection. This will be the case for pure checking functions
// that do not want to change direction state.
if pktInfo.RemotePort() == 0 {
return CheckPID(socketInfo, pktInfo.Inbound)
}
// Get (and save) the direction of the connection.
connInbound := table.getDirection(socketInfo, pktInfo)
// Check we have the PID and return.
return CheckPID(socketInfo, connInbound)
}
// DUAL-STACK
// Skip if dualStack is not enabled.
if table.dualStack == nil {
continue
}
// Get or update tables.
if i == 1 && pktInfo.SeenAt.UnixNano() >= table.lastUpdateAt.Load() {
dualStackBinds = table.dualStack.getCurrentTables()
} else {
dualStackBinds = table.dualStack.updateTables()
}
// Check tables for socket.
socketInfo = findUDPSocket(pktInfo, dualStackBinds, isInboundMulticast)
// If there's a match, do some last checks and return.
if socketInfo != nil {
// If there is no remote port, do check for the direction of the
// connection. This will be the case for pure checking functions
// that do not want to change direction state.
if pktInfo.RemotePort() == 0 {
return CheckPID(socketInfo, pktInfo.Inbound)
}
// Get (and save) the direction of the connection.
connInbound := table.getDirection(socketInfo, pktInfo)
// Check we have the PID and return.
return CheckPID(socketInfo, connInbound)
}
// Search less if we want to be fast.
if fast && i >= fastLookupTries {
break
}
}
return socket.UndefinedProcessID, pktInfo.Inbound, ErrConnectionNotFound
}
func findUDPSocket(pktInfo *packet.Info, binds []*socket.BindInfo, isInboundMulticast bool) (socketInfo *socket.BindInfo) {
localIP := pktInfo.LocalIP()
localPort := pktInfo.LocalPort()
// search binds
for _, socketInfo := range binds {
if localPort == socketInfo.Local.Port &&
(socketInfo.ListensAny || // zero IP (dual-stack)
isInboundMulticast || // inbound broadcast, multicast
localIP.Equal(socketInfo.Local.IP)) {
return socketInfo
}
}
return nil
}