diff options
| -rw-r--r-- | pkg/abi/linux/netfilter.go | 24 | ||||
| -rw-r--r-- | pkg/sentry/socket/netfilter/netfilter.go | 21 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/iptables.go | 28 | ||||
| -rw-r--r-- | pkg/tcpip/iptables/types.go | 12 | ||||
| -rw-r--r-- | test/iptables/filter_input.go | 65 | ||||
| -rw-r--r-- | test/iptables/filter_output.go | 56 | ||||
| -rw-r--r-- | test/iptables/iptables_test.go | 66 | ||||
| -rw-r--r-- | test/iptables/iptables_util.go | 25 | ||||
| -rw-r--r-- | test/iptables/nat.go | 201 |
9 files changed, 486 insertions, 12 deletions
diff --git a/pkg/abi/linux/netfilter.go b/pkg/abi/linux/netfilter.go index e20c625f7..80dc09aa9 100644 --- a/pkg/abi/linux/netfilter.go +++ b/pkg/abi/linux/netfilter.go @@ -158,10 +158,32 @@ type IPTIP struct { // Flags define matching behavior for the IP header. Flags uint8 - // InverseFlags invert the meaning of fields in struct IPTIP. + // InverseFlags invert the meaning of fields in struct IPTIP. See the + // IPT_INV_* flags. InverseFlags uint8 } +// Flags in IPTIP.InverseFlags. Corresponding constants are in +// include/uapi/linux/netfilter_ipv4/ip_tables.h. +const ( + // Invert the meaning of InputInterface. + IPT_INV_VIA_IN = 0x01 + // Invert the meaning of OutputInterface. + IPT_INV_VIA_OUT = 0x02 + // Unclear what this is, as no references to it exist in the kernel. + IPT_INV_TOS = 0x04 + // Invert the meaning of Src. + IPT_INV_SRCIP = 0x08 + // Invert the meaning of Dst. + IPT_INV_DSTIP = 0x10 + // Invert the meaning of the IPT_F_FRAG flag. + IPT_INV_FRAG = 0x20 + // Invert the meaning of the Protocol field. + IPT_INV_PROTO = 0x40 + // Enable all flags. + IPT_INV_MASK = 0x7F +) + // SizeOfIPTIP is the size of an IPTIP. const SizeOfIPTIP = 84 diff --git a/pkg/sentry/socket/netfilter/netfilter.go b/pkg/sentry/socket/netfilter/netfilter.go index e57ef02a1..b5b9be46f 100644 --- a/pkg/sentry/socket/netfilter/netfilter.go +++ b/pkg/sentry/socket/netfilter/netfilter.go @@ -703,25 +703,34 @@ func filterFromIPTIP(iptip linux.IPTIP) (iptables.IPHeaderFilter, error) { if containsUnsupportedFields(iptip) { return iptables.IPHeaderFilter{}, fmt.Errorf("unsupported fields in struct iptip: %+v", iptip) } + if len(iptip.Dst) != header.IPv4AddressSize || len(iptip.DstMask) != header.IPv4AddressSize { + return iptables.IPHeaderFilter{}, fmt.Errorf("incorrect length of destination (%d) and/or destination mask (%d) fields", len(iptip.Dst), len(iptip.DstMask)) + } return iptables.IPHeaderFilter{ - Protocol: tcpip.TransportProtocolNumber(iptip.Protocol), + Protocol: tcpip.TransportProtocolNumber(iptip.Protocol), + Dst: tcpip.Address(iptip.Dst[:]), + DstMask: tcpip.Address(iptip.DstMask[:]), + DstInvert: iptip.InverseFlags&linux.IPT_INV_DSTIP != 0, }, nil } func containsUnsupportedFields(iptip linux.IPTIP) bool { - // Currently we check that everything except protocol is zeroed. + // The following features are supported: + // - Protocol + // - Dst and DstMask + // - The inverse destination IP check flag var emptyInetAddr = linux.InetAddr{} var emptyInterface = [linux.IFNAMSIZ]byte{} - return iptip.Dst != emptyInetAddr || - iptip.Src != emptyInetAddr || + // Disable any supported inverse flags. + inverseMask := uint8(linux.IPT_INV_DSTIP) + return iptip.Src != emptyInetAddr || iptip.SrcMask != emptyInetAddr || - iptip.DstMask != emptyInetAddr || iptip.InputInterface != emptyInterface || iptip.OutputInterface != emptyInterface || iptip.InputInterfaceMask != emptyInterface || iptip.OutputInterfaceMask != emptyInterface || iptip.Flags != 0 || - iptip.InverseFlags != 0 + iptip.InverseFlags&^inverseMask != 0 } func validUnderflow(rule iptables.Rule) bool { diff --git a/pkg/tcpip/iptables/iptables.go b/pkg/tcpip/iptables/iptables.go index 2ab9e0675..d30571c74 100644 --- a/pkg/tcpip/iptables/iptables.go +++ b/pkg/tcpip/iptables/iptables.go @@ -267,9 +267,8 @@ func (it *IPTables) checkRule(hook Hook, pkt tcpip.PacketBuffer, table Table, ru pkt.NetworkHeader = pkt.Data.First() } - // First check whether the packet matches the IP header filter. - // TODO(gvisor.dev/issue/170): Support other fields of the filter. - if rule.Filter.Protocol != 0 && rule.Filter.Protocol != header.IPv4(pkt.NetworkHeader).TransportProtocol() { + // Check whether the packet matches the IP header filter. + if !filterMatch(rule.Filter, header.IPv4(pkt.NetworkHeader)) { // Continue on to the next rule. return RuleJump, ruleIdx + 1 } @@ -290,3 +289,26 @@ func (it *IPTables) checkRule(hook Hook, pkt tcpip.PacketBuffer, table Table, ru // All the matchers matched, so run the target. return rule.Target.Action(pkt) } + +func filterMatch(filter IPHeaderFilter, hdr header.IPv4) bool { + // TODO(gvisor.dev/issue/170): Support other fields of the filter. + // Check the transport protocol. + if filter.Protocol != 0 && filter.Protocol != hdr.TransportProtocol() { + return false + } + + // Check the destination IP. + dest := hdr.DestinationAddress() + matches := true + for i := range filter.Dst { + if dest[i]&filter.DstMask[i] != filter.Dst[i] { + matches = false + break + } + } + if matches == filter.DstInvert { + return false + } + + return true +} diff --git a/pkg/tcpip/iptables/types.go b/pkg/tcpip/iptables/types.go index 7d032fd23..e7fcf6bff 100644 --- a/pkg/tcpip/iptables/types.go +++ b/pkg/tcpip/iptables/types.go @@ -144,6 +144,18 @@ type Rule struct { type IPHeaderFilter struct { // Protocol matches the transport protocol. Protocol tcpip.TransportProtocolNumber + + // Dst matches the destination IP address. + Dst tcpip.Address + + // DstMask masks bits of the destination IP address when comparing with + // Dst. + DstMask tcpip.Address + + // DstInvert inverts the meaning of the destination IP check, i.e. when + // true the filter will match packets that fail the destination + // comparison. + DstInvert bool } // A Matcher is the interface for matching packets. diff --git a/test/iptables/filter_input.go b/test/iptables/filter_input.go index 141d20fbb..05647de33 100644 --- a/test/iptables/filter_input.go +++ b/test/iptables/filter_input.go @@ -47,6 +47,8 @@ func init() { RegisterTestCase(FilterInputJumpReturnDrop{}) RegisterTestCase(FilterInputJumpBuiltin{}) RegisterTestCase(FilterInputJumpTwice{}) + RegisterTestCase(FilterInputDestination{}) + RegisterTestCase(FilterInputInvertDestination{}) } // FilterInputDropUDP tests that we can drop UDP traffic. @@ -596,3 +598,66 @@ func (FilterInputJumpTwice) ContainerAction(ip net.IP) error { func (FilterInputJumpTwice) LocalAction(ip net.IP) error { return sendUDPLoop(ip, acceptPort, sendloopDuration) } + +// FilterInputDestination verifies that we can filter packets via `-d +// <ipaddr>`. +type FilterInputDestination struct{} + +// Name implements TestCase.Name. +func (FilterInputDestination) Name() string { + return "FilterInputDestination" +} + +// ContainerAction implements TestCase.ContainerAction. +func (FilterInputDestination) ContainerAction(ip net.IP) error { + addrs, err := localAddrs() + if err != nil { + return err + } + + // Make INPUT's default action DROP, then ACCEPT all packets bound for + // this machine. + rules := [][]string{{"-P", "INPUT", "DROP"}} + for _, addr := range addrs { + rules = append(rules, []string{"-A", "INPUT", "-d", addr, "-j", "ACCEPT"}) + } + if err := filterTableRules(rules); err != nil { + return err + } + + return listenUDP(acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (FilterInputDestination) LocalAction(ip net.IP) error { + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} + +// FilterInputInvertDestination verifies that we can filter packets via `! -d +// <ipaddr>`. +type FilterInputInvertDestination struct{} + +// Name implements TestCase.Name. +func (FilterInputInvertDestination) Name() string { + return "FilterInputInvertDestination" +} + +// ContainerAction implements TestCase.ContainerAction. +func (FilterInputInvertDestination) ContainerAction(ip net.IP) error { + // Make INPUT's default action DROP, then ACCEPT all packets not bound + // for 127.0.0.1. + rules := [][]string{ + {"-P", "INPUT", "DROP"}, + {"-A", "INPUT", "!", "-d", localIP, "-j", "ACCEPT"}, + } + if err := filterTableRules(rules); err != nil { + return err + } + + return listenUDP(acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (FilterInputInvertDestination) LocalAction(ip net.IP) error { + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} diff --git a/test/iptables/filter_output.go b/test/iptables/filter_output.go index 1314a5a92..4582d514c 100644 --- a/test/iptables/filter_output.go +++ b/test/iptables/filter_output.go @@ -22,6 +22,8 @@ import ( func init() { RegisterTestCase(FilterOutputDropTCPDestPort{}) RegisterTestCase(FilterOutputDropTCPSrcPort{}) + RegisterTestCase(FilterOutputDestination{}) + RegisterTestCase(FilterOutputInvertDestination{}) } // FilterOutputDropTCPDestPort tests that connections are not accepted on @@ -87,3 +89,57 @@ func (FilterOutputDropTCPSrcPort) LocalAction(ip net.IP) error { return nil } + +// FilterOutputDestination tests that we can selectively allow packets to +// certain destinations. +type FilterOutputDestination struct{} + +// Name implements TestCase.Name. +func (FilterOutputDestination) Name() string { + return "FilterOutputDestination" +} + +// ContainerAction implements TestCase.ContainerAction. +func (FilterOutputDestination) ContainerAction(ip net.IP) error { + rules := [][]string{ + {"-A", "OUTPUT", "-d", ip.String(), "-j", "ACCEPT"}, + {"-P", "OUTPUT", "DROP"}, + } + if err := filterTableRules(rules); err != nil { + return err + } + + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (FilterOutputDestination) LocalAction(ip net.IP) error { + return listenUDP(acceptPort, sendloopDuration) +} + +// FilterOutputInvertDestination tests that we can selectively allow packets +// not headed for a particular destination. +type FilterOutputInvertDestination struct{} + +// Name implements TestCase.Name. +func (FilterOutputInvertDestination) Name() string { + return "FilterOutputInvertDestination" +} + +// ContainerAction implements TestCase.ContainerAction. +func (FilterOutputInvertDestination) ContainerAction(ip net.IP) error { + rules := [][]string{ + {"-A", "OUTPUT", "!", "-d", localIP, "-j", "ACCEPT"}, + {"-P", "OUTPUT", "DROP"}, + } + if err := filterTableRules(rules); err != nil { + return err + } + + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (FilterOutputInvertDestination) LocalAction(ip net.IP) error { + return listenUDP(acceptPort, sendloopDuration) +} diff --git a/test/iptables/iptables_test.go b/test/iptables/iptables_test.go index 56ba78107..73ba8b447 100644 --- a/test/iptables/iptables_test.go +++ b/test/iptables/iptables_test.go @@ -303,3 +303,69 @@ func TestJumpTwice(t *testing.T) { t.Fatal(err) } } + +func TestInputDestination(t *testing.T) { + if err := singleTest(FilterInputDestination{}); err != nil { + t.Fatal(err) + } +} + +func TestInputInvertDestination(t *testing.T) { + if err := singleTest(FilterInputInvertDestination{}); err != nil { + t.Fatal(err) + } +} + +func TestOutputDestination(t *testing.T) { + if err := singleTest(FilterOutputDestination{}); err != nil { + t.Fatal(err) + } +} + +func TestOutputInvertDestination(t *testing.T) { + if err := singleTest(FilterOutputInvertDestination{}); err != nil { + t.Fatal(err) + } +} + +func TestNATOutRedirectIP(t *testing.T) { + if err := singleTest(NATOutRedirectIP{}); err != nil { + t.Fatal(err) + } +} + +func TestNATOutDontRedirectIP(t *testing.T) { + if err := singleTest(NATOutDontRedirectIP{}); err != nil { + t.Fatal(err) + } +} + +func TestNATOutRedirectInvert(t *testing.T) { + if err := singleTest(NATOutRedirectInvert{}); err != nil { + t.Fatal(err) + } +} + +func TestNATPreRedirectIP(t *testing.T) { + if err := singleTest(NATPreRedirectIP{}); err != nil { + t.Fatal(err) + } +} + +func TestNATPreDontRedirectIP(t *testing.T) { + if err := singleTest(NATPreDontRedirectIP{}); err != nil { + t.Fatal(err) + } +} + +func TestNATPreRedirectInvert(t *testing.T) { + if err := singleTest(NATPreRedirectInvert{}); err != nil { + t.Fatal(err) + } +} + +func TestNATRedirectRequiresProtocol(t *testing.T) { + if err := singleTest(NATRedirectRequiresProtocol{}); err != nil { + t.Fatal(err) + } +} diff --git a/test/iptables/iptables_util.go b/test/iptables/iptables_util.go index 1f8dac4f1..e8ae65c5a 100644 --- a/test/iptables/iptables_util.go +++ b/test/iptables/iptables_util.go @@ -24,6 +24,7 @@ import ( ) const iptablesBinary = "iptables" +const localIP = "127.0.0.1" // filterTable calls `iptables -t filter` with the given args. func filterTable(args ...string) error { @@ -46,8 +47,17 @@ func tableCmd(table string, args []string) error { // filterTableRules is like filterTable, but runs multiple iptables commands. func filterTableRules(argsList [][]string) error { + return tableRules("filter", argsList) +} + +// natTableRules is like natTable, but runs multiple iptables commands. +func natTableRules(argsList [][]string) error { + return tableRules("nat", argsList) +} + +func tableRules(table string, argsList [][]string) error { for _, args := range argsList { - if err := filterTable(args...); err != nil { + if err := tableCmd(table, args); err != nil { return err } } @@ -146,3 +156,16 @@ func connectTCP(ip net.IP, port int, timeout time.Duration) error { return nil } + +// localAddrs returns a list of local network interface addresses. +func localAddrs() ([]string, error) { + addrs, err := net.InterfaceAddrs() + if err != nil { + return nil, err + } + addrStrs := make([]string, 0, len(addrs)) + for _, addr := range addrs { + addrStrs = append(addrStrs, addr.String()) + } + return addrStrs, nil +} diff --git a/test/iptables/nat.go b/test/iptables/nat.go index 6ca6b46ca..40096901c 100644 --- a/test/iptables/nat.go +++ b/test/iptables/nat.go @@ -15,8 +15,10 @@ package iptables import ( + "errors" "fmt" "net" + "time" ) const ( @@ -28,6 +30,13 @@ func init() { RegisterTestCase(NATRedirectTCPPort{}) RegisterTestCase(NATDropUDP{}) RegisterTestCase(NATAcceptAll{}) + RegisterTestCase(NATPreRedirectIP{}) + RegisterTestCase(NATPreDontRedirectIP{}) + RegisterTestCase(NATPreRedirectInvert{}) + RegisterTestCase(NATOutRedirectIP{}) + RegisterTestCase(NATOutDontRedirectIP{}) + RegisterTestCase(NATOutRedirectInvert{}) + RegisterTestCase(NATRedirectRequiresProtocol{}) } // NATRedirectUDPPort tests that packets are redirected to different port. @@ -79,7 +88,8 @@ func (NATRedirectTCPPort) LocalAction(ip net.IP) error { return connectTCP(ip, dropPort, sendloopDuration) } -// NATDropUDP tests that packets are not received in ports other than redirect port. +// NATDropUDP tests that packets are not received in ports other than redirect +// port. type NATDropUDP struct{} // Name implements TestCase.Name. @@ -130,3 +140,192 @@ func (NATAcceptAll) ContainerAction(ip net.IP) error { func (NATAcceptAll) LocalAction(ip net.IP) error { return sendUDPLoop(ip, acceptPort, sendloopDuration) } + +// NATOutRedirectIP uses iptables to select packets based on destination IP and +// redirects them. +type NATOutRedirectIP struct{} + +// Name implements TestCase.Name. +func (NATOutRedirectIP) Name() string { + return "NATOutRedirectIP" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATOutRedirectIP) ContainerAction(ip net.IP) error { + // Redirect OUTPUT packets to a listening localhost port. + dest := net.IP([]byte{200, 0, 0, 2}) + return loopbackTest(dest, "-A", "OUTPUT", "-d", dest.String(), "-p", "udp", "-j", "REDIRECT", "--to-port", fmt.Sprintf("%d", acceptPort)) +} + +// LocalAction implements TestCase.LocalAction. +func (NATOutRedirectIP) LocalAction(ip net.IP) error { + // No-op. + return nil +} + +// NATOutDontRedirectIP tests that iptables matching with "-d" does not match +// packets it shouldn't. +type NATOutDontRedirectIP struct{} + +// Name implements TestCase.Name. +func (NATOutDontRedirectIP) Name() string { + return "NATOutDontRedirectIP" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATOutDontRedirectIP) ContainerAction(ip net.IP) error { + if err := natTable("-A", "OUTPUT", "-d", localIP, "-p", "udp", "-j", "REDIRECT", "--to-port", fmt.Sprintf("%d", dropPort)); err != nil { + return err + } + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (NATOutDontRedirectIP) LocalAction(ip net.IP) error { + return listenUDP(acceptPort, sendloopDuration) +} + +// NATOutRedirectInvert tests that iptables can match with "! -d". +type NATOutRedirectInvert struct{} + +// Name implements TestCase.Name. +func (NATOutRedirectInvert) Name() string { + return "NATOutRedirectInvert" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATOutRedirectInvert) ContainerAction(ip net.IP) error { + // Redirect OUTPUT packets to a listening localhost port. + dest := []byte{200, 0, 0, 3} + destStr := "200.0.0.2" + return loopbackTest(dest, "-A", "OUTPUT", "!", "-d", destStr, "-p", "udp", "-j", "REDIRECT", "--to-port", fmt.Sprintf("%d", acceptPort)) +} + +// LocalAction implements TestCase.LocalAction. +func (NATOutRedirectInvert) LocalAction(ip net.IP) error { + // No-op. + return nil +} + +// NATPreRedirectIP tests that we can use iptables to select packets based on +// destination IP and redirect them. +type NATPreRedirectIP struct{} + +// Name implements TestCase.Name. +func (NATPreRedirectIP) Name() string { + return "NATPreRedirectIP" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATPreRedirectIP) ContainerAction(ip net.IP) error { + addrs, err := localAddrs() + if err != nil { + return err + } + + var rules [][]string + for _, addr := range addrs { + rules = append(rules, []string{"-A", "PREROUTING", "-p", "udp", "-d", addr, "-j", "REDIRECT", "--to-ports", fmt.Sprintf("%d", acceptPort)}) + } + if err := natTableRules(rules); err != nil { + return err + } + return listenUDP(acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (NATPreRedirectIP) LocalAction(ip net.IP) error { + return sendUDPLoop(ip, dropPort, sendloopDuration) +} + +// NATPreDontRedirectIP tests that iptables matching with "-d" does not match +// packets it shouldn't. +type NATPreDontRedirectIP struct{} + +// Name implements TestCase.Name. +func (NATPreDontRedirectIP) Name() string { + return "NATPreDontRedirectIP" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATPreDontRedirectIP) ContainerAction(ip net.IP) error { + if err := natTable("-A", "PREROUTING", "-p", "udp", "-d", localIP, "-j", "REDIRECT", "--to-ports", fmt.Sprintf("%d", dropPort)); err != nil { + return err + } + return listenUDP(acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (NATPreDontRedirectIP) LocalAction(ip net.IP) error { + return sendUDPLoop(ip, acceptPort, sendloopDuration) +} + +// NATPreRedirectInvert tests that iptables can match with "! -d". +type NATPreRedirectInvert struct{} + +// Name implements TestCase.Name. +func (NATPreRedirectInvert) Name() string { + return "NATPreRedirectInvert" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATPreRedirectInvert) ContainerAction(ip net.IP) error { + if err := natTable("-A", "PREROUTING", "-p", "udp", "!", "-d", localIP, "-j", "REDIRECT", "--to-ports", fmt.Sprintf("%d", acceptPort)); err != nil { + return err + } + return listenUDP(acceptPort, sendloopDuration) +} + +// LocalAction implements TestCase.LocalAction. +func (NATPreRedirectInvert) LocalAction(ip net.IP) error { + return sendUDPLoop(ip, dropPort, sendloopDuration) +} + +// NATRedirectRequiresProtocol tests that use of the --to-ports flag requires a +// protocol to be specified with -p. +type NATRedirectRequiresProtocol struct{} + +// Name implements TestCase.Name. +func (NATRedirectRequiresProtocol) Name() string { + return "NATRedirectRequiresProtocol" +} + +// ContainerAction implements TestCase.ContainerAction. +func (NATRedirectRequiresProtocol) ContainerAction(ip net.IP) error { + if err := natTable("-A", "PREROUTING", "-d", localIP, "-j", "REDIRECT", "--to-ports", fmt.Sprintf("%d", acceptPort)); err == nil { + return errors.New("expected an error using REDIRECT --to-ports without a protocol") + } + return nil +} + +// LocalAction implements TestCase.LocalAction. +func (NATRedirectRequiresProtocol) LocalAction(ip net.IP) error { + // No-op. + return nil +} + +// loopbackTests runs an iptables rule and ensures that packets sent to +// dest:dropPort are received by localhost:acceptPort. +func loopbackTest(dest net.IP, args ...string) error { + if err := natTable(args...); err != nil { + return err + } + sendCh := make(chan error) + listenCh := make(chan error) + go func() { + sendCh <- sendUDPLoop(dest, dropPort, sendloopDuration) + }() + go func() { + listenCh <- listenUDP(acceptPort, sendloopDuration) + }() + select { + case err := <-listenCh: + if err != nil { + return err + } + case <-time.After(sendloopDuration): + return errors.New("timed out") + } + // sendCh will always take the full sendloop time. + return <-sendCh +} |