diff options
Diffstat (limited to 'pkg/tcpip/stack/iptables_targets.go')
| -rw-r--r-- | pkg/tcpip/stack/iptables_targets.go | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/pkg/tcpip/stack/iptables_targets.go b/pkg/tcpip/stack/iptables_targets.go index 94a5df329..ff55ef1a3 100644 --- a/pkg/tcpip/stack/iptables_targets.go +++ b/pkg/tcpip/stack/iptables_targets.go @@ -15,6 +15,8 @@ package stack import ( + "fmt" + "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/header" @@ -81,25 +83,34 @@ func (*ReturnTarget) Action(*PacketBuffer, *ConnTrack, Hook, *GSO, *Route, tcpip return RuleReturn, 0 } -// RedirectTarget redirects the packet by modifying the destination port/IP. +// RedirectTarget redirects the packet to this machine by modifying the +// destination port/IP. Outgoing packets are redirected to the loopback device, +// and incoming packets are redirected to the incoming interface (rather than +// forwarded). +// // TODO(gvisor.dev/issue/170): Other flags need to be added after we support // them. type RedirectTarget struct { - // Addr indicates address used to redirect. - Addr tcpip.Address - - // Port indicates port used to redirect. + // Port indicates port used to redirect. It is immutable. Port uint16 - // NetworkProtocol is the network protocol the target is used with. + // NetworkProtocol is the network protocol the target is used with. It + // is immutable. NetworkProtocol tcpip.NetworkProtocolNumber } // Action implements Target.Action. // TODO(gvisor.dev/issue/170): Parse headers without copying. The current -// implementation only works for PREROUTING and calls pkt.Clone(), neither +// implementation only works for Prerouting and calls pkt.Clone(), neither // of which should be the case. func (rt *RedirectTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, gso *GSO, r *Route, address tcpip.Address) (RuleVerdict, int) { + // Sanity check. + if rt.NetworkProtocol != pkt.NetworkProtocolNumber { + panic(fmt.Sprintf( + "RedirectTarget.Action with NetworkProtocol %d called on packet with NetworkProtocolNumber %d", + rt.NetworkProtocol, pkt.NetworkProtocolNumber)) + } + // Packet is already manipulated. if pkt.NatDone { return RuleAccept, 0 @@ -110,17 +121,17 @@ func (rt *RedirectTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, gs return RuleDrop, 0 } - // Change the address to localhost (127.0.0.1 or ::1) in Output and to + // Change the address to loopback (127.0.0.1 or ::1) in Output and to // the primary address of the incoming interface in Prerouting. switch hook { case Output: if pkt.NetworkProtocolNumber == header.IPv4ProtocolNumber { - rt.Addr = tcpip.Address([]byte{127, 0, 0, 1}) + address = tcpip.Address([]byte{127, 0, 0, 1}) } else { - rt.Addr = header.IPv6Loopback + address = header.IPv6Loopback } case Prerouting: - rt.Addr = address + // No-op, as address is already set correctly. default: panic("redirect target is supported only on output and prerouting hooks") } @@ -148,7 +159,7 @@ func (rt *RedirectTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, gs } } - pkt.Network().SetDestinationAddress(rt.Addr) + pkt.Network().SetDestinationAddress(address) // After modification, IPv4 packets need a valid checksum. if pkt.NetworkProtocolNumber == header.IPv4ProtocolNumber { @@ -165,7 +176,7 @@ func (rt *RedirectTarget) Action(pkt *PacketBuffer, ct *ConnTrack, hook Hook, gs // Set up conection for matching NAT rule. Only the first // packet of the connection comes here. Other packets will be // manipulated in connection tracking. - if conn := ct.insertRedirectConn(pkt, hook, rt); conn != nil { + if conn := ct.insertRedirectConn(pkt, hook, rt.Port, address); conn != nil { ct.handlePacket(pkt, hook, gso, r) } default: |