From f82dd8ddb477b8923d1db12654a62d55d613019c Mon Sep 17 00:00:00 2001 From: Fabricio Voznika Date: Tue, 28 Jul 2020 21:22:52 -0700 Subject: Redirect TODO to GitHub issues PiperOrigin-RevId: 323715260 --- pkg/sentry/socket/netstack/netstack.go | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'pkg/sentry/socket/netstack') diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go index 44b3fff46..f86e6cd7a 100644 --- a/pkg/sentry/socket/netstack/netstack.go +++ b/pkg/sentry/socket/netstack/netstack.go @@ -423,7 +423,7 @@ func AddressAndFamily(addr []byte) (tcpip.FullAddress, uint16, *syserr.Error) { return tcpip.FullAddress{}, family, syserr.ErrInvalidArgument } - // TODO(b/129292371): Return protocol too. + // TODO(gvisor.dev/issue/173): Return protocol too. return tcpip.FullAddress{ NIC: tcpip.NICID(a.InterfaceIndex), Addr: tcpip.Address(a.HardwareAddr[:header.EthernetAddressSize]), @@ -2418,7 +2418,7 @@ func ConvertAddress(family int, addr tcpip.FullAddress) (linux.SockAddr, uint32) return &out, uint32(sockAddrInet6Size) case linux.AF_PACKET: - // TODO(b/129292371): Return protocol too. + // TODO(gvisor.dev/issue/173): Return protocol too. var out linux.SockAddrLink out.Family = linux.AF_PACKET out.InterfaceIndex = int32(addr.NIC) -- cgit v1.2.3 From 2a7b2a61e3ea32129c26eeaa6fab3d81a5d8ad6e Mon Sep 17 00:00:00 2001 From: Kevin Krakauer Date: Thu, 11 Jun 2020 20:33:56 -0700 Subject: iptables: support SO_ORIGINAL_DST Envoy (#170) uses this to get the original destination of redirected packets. --- pkg/abi/linux/netfilter.go | 8 +- pkg/abi/linux/socket.go | 4 +- pkg/sentry/socket/netstack/netstack.go | 17 ++++ pkg/sentry/strace/socket.go | 1 + pkg/tcpip/stack/conntrack.go | 26 ++++++ pkg/tcpip/stack/iptables.go | 11 ++- pkg/tcpip/tcpip.go | 4 + pkg/tcpip/transport/tcp/endpoint.go | 11 +++ test/iptables/BUILD | 1 + test/iptables/iptables_test.go | 8 ++ test/iptables/iptables_unsafe.go | 63 ++++++++++++++ test/iptables/iptables_util.go | 51 ++++++++++- test/iptables/nat.go | 152 ++++++++++++++++++++++++++++++++- 13 files changed, 344 insertions(+), 13 deletions(-) create mode 100644 test/iptables/iptables_unsafe.go (limited to 'pkg/sentry/socket/netstack') diff --git a/pkg/abi/linux/netfilter.go b/pkg/abi/linux/netfilter.go index a91f9f018..9c27f7bb2 100644 --- a/pkg/abi/linux/netfilter.go +++ b/pkg/abi/linux/netfilter.go @@ -59,7 +59,7 @@ var VerdictStrings = map[int32]string{ NF_RETURN: "RETURN", } -// Socket options. These correspond to values in +// Socket options for SOL_SOCKET. These correspond to values in // include/uapi/linux/netfilter_ipv4/ip_tables.h. const ( IPT_BASE_CTL = 64 @@ -74,6 +74,12 @@ const ( IPT_SO_GET_MAX = IPT_SO_GET_REVISION_TARGET ) +// Socket option for SOL_IP. This corresponds to the value in +// include/uapi/linux/netfilter_ipv4.h. +const ( + SO_ORIGINAL_DST = 80 +) + // Name lengths. These correspond to values in // include/uapi/linux/netfilter/x_tables.h. const ( diff --git a/pkg/abi/linux/socket.go b/pkg/abi/linux/socket.go index c24a8216e..d6946bb82 100644 --- a/pkg/abi/linux/socket.go +++ b/pkg/abi/linux/socket.go @@ -239,11 +239,13 @@ const SockAddrMax = 128 type InetAddr [4]byte // SockAddrInet is struct sockaddr_in, from uapi/linux/in.h. +// +// +marshal type SockAddrInet struct { Family uint16 Port uint16 Addr InetAddr - Zero [8]uint8 // pad to sizeof(struct sockaddr). + _ [8]uint8 // pad to sizeof(struct sockaddr). } // InetMulticastRequest is struct ip_mreq, from uapi/linux/in.h. diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go index f86e6cd7a..31a168f7e 100644 --- a/pkg/sentry/socket/netstack/netstack.go +++ b/pkg/sentry/socket/netstack/netstack.go @@ -1490,6 +1490,10 @@ func getSockOptIPv6(t *kernel.Task, ep commonEndpoint, name, outLen int) (marsha vP := primitive.Int32(boolToInt32(v)) return &vP, nil + case linux.SO_ORIGINAL_DST: + // TODO(gvisor.dev/issue/170): ip6tables. + return nil, syserr.ErrInvalidArgument + default: emitUnimplementedEventIPv6(t, name) } @@ -1600,6 +1604,19 @@ func getSockOptIP(t *kernel.Task, ep commonEndpoint, name, outLen int, family in vP := primitive.Int32(boolToInt32(v)) return &vP, nil + case linux.SO_ORIGINAL_DST: + if outLen < int(binary.Size(linux.SockAddrInet{})) { + return nil, syserr.ErrInvalidArgument + } + + var v tcpip.OriginalDestinationOption + if err := ep.GetSockOpt(&v); err != nil { + return nil, syserr.TranslateNetstackError(err) + } + + a, _ := ConvertAddress(linux.AF_INET, tcpip.FullAddress(v)) + return a.(*linux.SockAddrInet), nil + default: emitUnimplementedEventIP(t, name) } diff --git a/pkg/sentry/strace/socket.go b/pkg/sentry/strace/socket.go index c0512de89..b51c4c941 100644 --- a/pkg/sentry/strace/socket.go +++ b/pkg/sentry/strace/socket.go @@ -521,6 +521,7 @@ var sockOptNames = map[uint64]abi.ValueSet{ linux.IP_ROUTER_ALERT: "IP_ROUTER_ALERT", linux.IP_PKTOPTIONS: "IP_PKTOPTIONS", linux.IP_MTU: "IP_MTU", + linux.SO_ORIGINAL_DST: "SO_ORIGINAL_DST", }, linux.SOL_SOCKET: { linux.SO_ERROR: "SO_ERROR", diff --git a/pkg/tcpip/stack/conntrack.go b/pkg/tcpip/stack/conntrack.go index 559a1c4dd..470c265aa 100644 --- a/pkg/tcpip/stack/conntrack.go +++ b/pkg/tcpip/stack/conntrack.go @@ -240,7 +240,10 @@ func (ct *ConnTrack) connFor(pkt *PacketBuffer) (*conn, direction) { if err != nil { return nil, dirOriginal } + return ct.connForTID(tid) +} +func (ct *ConnTrack) connForTID(tid tupleID) (*conn, direction) { bucket := ct.bucket(tid) now := time.Now() @@ -604,3 +607,26 @@ func (ct *ConnTrack) reapTupleLocked(tuple *tuple, bucket int, now time.Time) bo return true } + +func (ct *ConnTrack) originalDst(epID TransportEndpointID) (tcpip.Address, uint16, *tcpip.Error) { + // Lookup the connection. The reply's original destination + // describes the original address. + tid := tupleID{ + srcAddr: epID.LocalAddress, + srcPort: epID.LocalPort, + dstAddr: epID.RemoteAddress, + dstPort: epID.RemotePort, + transProto: header.TCPProtocolNumber, + netProto: header.IPv4ProtocolNumber, + } + conn, _ := ct.connForTID(tid) + if conn == nil { + // Not a tracked connection. + return "", 0, tcpip.ErrNotConnected + } else if conn.manip == manipNone { + // Unmanipulated connection. + return "", 0, tcpip.ErrInvalidOptionValue + } + + return conn.original.dstAddr, conn.original.dstPort, nil +} diff --git a/pkg/tcpip/stack/iptables.go b/pkg/tcpip/stack/iptables.go index cbbae4224..110ba073d 100644 --- a/pkg/tcpip/stack/iptables.go +++ b/pkg/tcpip/stack/iptables.go @@ -218,19 +218,16 @@ func (it *IPTables) Check(hook Hook, pkt *PacketBuffer, gso *GSO, r *Route, addr // Many users never configure iptables. Spare them the cost of rule // traversal if rules have never been set. it.mu.RLock() + defer it.mu.RUnlock() if !it.modified { - it.mu.RUnlock() return true } - it.mu.RUnlock() // Packets are manipulated only if connection and matching // NAT rule exists. shouldTrack := it.connections.handlePacket(pkt, hook, gso, r) // Go through each table containing the hook. - it.mu.RLock() - defer it.mu.RUnlock() priorities := it.priorities[hook] for _, tableID := range priorities { // If handlePacket already NATed the packet, we don't need to @@ -418,3 +415,9 @@ func (it *IPTables) checkRule(hook Hook, pkt *PacketBuffer, table Table, ruleIdx // All the matchers matched, so run the target. return rule.Target.Action(pkt, &it.connections, hook, gso, r, address) } + +// OriginalDst returns the original destination of redirected connections. It +// returns an error if the connection doesn't exist or isn't redirected. +func (it *IPTables) OriginalDst(epID TransportEndpointID) (tcpip.Address, uint16, *tcpip.Error) { + return it.connections.originalDst(epID) +} diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go index a634b9b60..45f59b60f 100644 --- a/pkg/tcpip/tcpip.go +++ b/pkg/tcpip/tcpip.go @@ -954,6 +954,10 @@ type DefaultTTLOption uint8 // classic BPF filter on a given endpoint. type SocketDetachFilterOption int +// OriginalDestinationOption is used to get the original destination address +// and port of a redirected packet. +type OriginalDestinationOption FullAddress + // IPPacketInfo is the message structure for IP_PKTINFO. // // +stateify savable diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index 0f7487963..682687ebe 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -2017,6 +2017,17 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error { *o = tcpip.TCPDeferAcceptOption(e.deferAccept) e.UnlockUser() + case *tcpip.OriginalDestinationOption: + ipt := e.stack.IPTables() + addr, port, err := ipt.OriginalDst(e.ID) + if err != nil { + return err + } + *o = tcpip.OriginalDestinationOption{ + Addr: addr, + Port: port, + } + default: return tcpip.ErrUnknownProtocolOption } diff --git a/test/iptables/BUILD b/test/iptables/BUILD index 40b63ebbe..66453772a 100644 --- a/test/iptables/BUILD +++ b/test/iptables/BUILD @@ -9,6 +9,7 @@ go_library( "filter_input.go", "filter_output.go", "iptables.go", + "iptables_unsafe.go", "iptables_util.go", "nat.go", ], diff --git a/test/iptables/iptables_test.go b/test/iptables/iptables_test.go index 550b6198a..fda5f694f 100644 --- a/test/iptables/iptables_test.go +++ b/test/iptables/iptables_test.go @@ -371,3 +371,11 @@ func TestFilterAddrs(t *testing.T) { } } } + +func TestNATPreOriginalDst(t *testing.T) { + singleTest(t, NATPreOriginalDst{}) +} + +func TestNATOutOriginalDst(t *testing.T) { + singleTest(t, NATOutOriginalDst{}) +} diff --git a/test/iptables/iptables_unsafe.go b/test/iptables/iptables_unsafe.go new file mode 100644 index 000000000..bd85a8fea --- /dev/null +++ b/test/iptables/iptables_unsafe.go @@ -0,0 +1,63 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package iptables + +import ( + "fmt" + "syscall" + "unsafe" +) + +type originalDstError struct { + errno syscall.Errno +} + +func (e originalDstError) Error() string { + return fmt.Sprintf("errno (%d) when calling getsockopt(SO_ORIGINAL_DST): %v", int(e.errno), e.errno.Error()) +} + +// SO_ORIGINAL_DST gets the original destination of a redirected packet via +// getsockopt. +const SO_ORIGINAL_DST = 80 + +func originalDestination4(connfd int) (syscall.RawSockaddrInet4, error) { + var addr syscall.RawSockaddrInet4 + var addrLen uint32 = syscall.SizeofSockaddrInet4 + if errno := originalDestination(connfd, syscall.SOL_IP, unsafe.Pointer(&addr), &addrLen); errno != 0 { + return syscall.RawSockaddrInet4{}, originalDstError{errno} + } + return addr, nil +} + +func originalDestination6(connfd int) (syscall.RawSockaddrInet6, error) { + var addr syscall.RawSockaddrInet6 + var addrLen uint32 = syscall.SizeofSockaddrInet6 + if errno := originalDestination(connfd, syscall.SOL_IPV6, unsafe.Pointer(&addr), &addrLen); errno != 0 { + return syscall.RawSockaddrInet6{}, originalDstError{errno} + } + return addr, nil +} + +func originalDestination(connfd int, level uintptr, optval unsafe.Pointer, optlen *uint32) syscall.Errno { + _, _, errno := syscall.Syscall6( + syscall.SYS_GETSOCKOPT, + uintptr(connfd), + level, + SO_ORIGINAL_DST, + uintptr(optval), + uintptr(unsafe.Pointer(optlen)), + 0) + return errno +} diff --git a/test/iptables/iptables_util.go b/test/iptables/iptables_util.go index ca80a4b5f..5125fe47b 100644 --- a/test/iptables/iptables_util.go +++ b/test/iptables/iptables_util.go @@ -15,6 +15,8 @@ package iptables import ( + "encoding/binary" + "errors" "fmt" "net" "os/exec" @@ -218,17 +220,58 @@ func filterAddrs(addrs []string, ipv6 bool) []string { // getInterfaceName returns the name of the interface other than loopback. func getInterfaceName() (string, bool) { - var ifname string + iface, ok := getNonLoopbackInterface() + if !ok { + return "", false + } + return iface.Name, true +} + +func getInterfaceAddrs(ipv6 bool) ([]net.IP, error) { + iface, ok := getNonLoopbackInterface() + if !ok { + return nil, errors.New("no non-loopback interface found") + } + addrs, err := iface.Addrs() + if err != nil { + return nil, err + } + + // Get only IPv4 or IPv6 addresses. + ips := make([]net.IP, 0, len(addrs)) + for _, addr := range addrs { + parts := strings.Split(addr.String(), "/") + var ip net.IP + // To16() returns IPv4 addresses as IPv4-mapped IPv6 addresses. + // So we check whether To4() returns nil to test whether the + // address is v4 or v6. + if v4 := net.ParseIP(parts[0]).To4(); ipv6 && v4 == nil { + ip = net.ParseIP(parts[0]).To16() + } else { + ip = v4 + } + if ip != nil { + ips = append(ips, ip) + } + } + return ips, nil +} + +func getNonLoopbackInterface() (net.Interface, bool) { if interfaces, err := net.Interfaces(); err == nil { for _, intf := range interfaces { if intf.Name != "lo" { - ifname = intf.Name - break + return intf, true } } } + return net.Interface{}, false +} - return ifname, ifname != "" +func htons(x uint16) uint16 { + buf := make([]byte, 2) + binary.BigEndian.PutUint16(buf, x) + return binary.LittleEndian.Uint16(buf) } func localIP(ipv6 bool) string { diff --git a/test/iptables/nat.go b/test/iptables/nat.go index ac0d91bb2..b7fea2527 100644 --- a/test/iptables/nat.go +++ b/test/iptables/nat.go @@ -18,12 +18,11 @@ import ( "errors" "fmt" "net" + "syscall" "time" ) -const ( - redirectPort = 42 -) +const redirectPort = 42 func init() { RegisterTestCase(NATPreRedirectUDPPort{}) @@ -42,6 +41,8 @@ func init() { RegisterTestCase(NATOutRedirectInvert{}) RegisterTestCase(NATRedirectRequiresProtocol{}) RegisterTestCase(NATLoopbackSkipsPrerouting{}) + RegisterTestCase(NATPreOriginalDst{}) + RegisterTestCase(NATOutOriginalDst{}) } // NATPreRedirectUDPPort tests that packets are redirected to different port. @@ -471,6 +472,151 @@ func (NATLoopbackSkipsPrerouting) LocalAction(ip net.IP, ipv6 bool) error { return nil } +// NATPreOriginalDst tests that SO_ORIGINAL_DST returns the pre-NAT destination +// of PREROUTING NATted packets. +type NATPreOriginalDst struct{} + +// Name implements TestCase.Name. +func (NATPreOriginalDst) Name() string { + return "NATPreOriginalDst" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATPreOriginalDst) ContainerAction(ip net.IP, ipv6 bool) error { + // Redirect incoming TCP connections to acceptPort. + if err := natTable(ipv6, "-A", "PREROUTING", + "-p", "tcp", + "--destination-port", fmt.Sprintf("%d", dropPort), + "-j", "REDIRECT", "--to-port", fmt.Sprintf("%d", acceptPort)); err != nil { + return err + } + + addrs, err := getInterfaceAddrs(ipv6) + if err != nil { + return err + } + return listenForRedirectedConn(ipv6, addrs) +} + +// LocalAction implements TestCase.LocalAction. +func (NATPreOriginalDst) LocalAction(ip net.IP, ipv6 bool) error { + return connectTCP(ip, dropPort, sendloopDuration) +} + +// NATOutOriginalDst tests that SO_ORIGINAL_DST returns the pre-NAT destination +// of OUTBOUND NATted packets. +type NATOutOriginalDst struct{} + +// Name implements TestCase.Name. +func (NATOutOriginalDst) Name() string { + return "NATOutOriginalDst" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATOutOriginalDst) ContainerAction(ip net.IP, ipv6 bool) error { + // Redirect incoming TCP connections to acceptPort. + if err := natTable(ipv6, "-A", "OUTPUT", "-p", "tcp", "-j", "REDIRECT", "--to-port", fmt.Sprintf("%d", acceptPort)); err != nil { + return err + } + + connCh := make(chan error) + go func() { + connCh <- connectTCP(ip, dropPort, sendloopDuration) + }() + + if err := listenForRedirectedConn(ipv6, []net.IP{ip}); err != nil { + return err + } + return <-connCh +} + +// LocalAction implements TestCase.LocalAction. +func (NATOutOriginalDst) LocalAction(ip net.IP, ipv6 bool) error { + // No-op. + return nil +} + +func listenForRedirectedConn(ipv6 bool, originalDsts []net.IP) error { + // The net package doesn't give guarantee access to the connection's + // underlying FD, and thus we cannot call getsockopt. We have to use + // traditional syscalls for SO_ORIGINAL_DST. + + // Create the listening socket, bind, listen, and accept. + family := syscall.AF_INET + if ipv6 { + family = syscall.AF_INET6 + } + sockfd, err := syscall.Socket(family, syscall.SOCK_STREAM, 0) + if err != nil { + return err + } + defer syscall.Close(sockfd) + + var bindAddr syscall.Sockaddr + if ipv6 { + bindAddr = &syscall.SockaddrInet6{ + Port: acceptPort, + Addr: [16]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, // in6addr_any + } + } else { + bindAddr = &syscall.SockaddrInet4{ + Port: acceptPort, + Addr: [4]byte{0, 0, 0, 0}, // INADDR_ANY + } + } + if err := syscall.Bind(sockfd, bindAddr); err != nil { + return err + } + + if err := syscall.Listen(sockfd, 1); err != nil { + return err + } + + connfd, _, err := syscall.Accept(sockfd) + if err != nil { + return err + } + defer syscall.Close(connfd) + + // Verify that, despite listening on acceptPort, SO_ORIGINAL_DST + // indicates the packet was sent to originalDst:dropPort. + if ipv6 { + got, err := originalDestination6(connfd) + if err != nil { + return err + } + // The original destination could be any of our IPs. + for _, dst := range originalDsts { + want := syscall.RawSockaddrInet6{ + Family: syscall.AF_INET6, + Port: htons(dropPort), + } + copy(want.Addr[:], dst.To16()) + if got == want { + return nil + } + } + return fmt.Errorf("SO_ORIGINAL_DST returned %+v, but wanted one of %+v (note: port numbers are in network byte order)", got, originalDsts) + } else { + got, err := originalDestination4(connfd) + if err != nil { + return err + } + // The original destination could be any of our IPs. + for _, dst := range originalDsts { + want := syscall.RawSockaddrInet4{ + Family: syscall.AF_INET, + Port: htons(dropPort), + } + copy(want.Addr[:], dst.To4()) + if got == want { + return nil + } + } + return fmt.Errorf("SO_ORIGINAL_DST returned %+v, but wanted one of %+v (note: port numbers are in network byte order)", got, originalDsts) + } +} + // loopbackTests runs an iptables rule and ensures that packets sent to // dest:dropPort are received by localhost:acceptPort. func loopbackTest(ipv6 bool, dest net.IP, args ...string) error { -- cgit v1.2.3